A SEMI-EMPIRICAL MODEL FOR CHARACTERISATION OF FLOW COEFFICIENT FOR PNEUMATIC SOLENOID VALVES

A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics of small electro-pneumatic (EP) valves within a wide range of pressure ratio. As a basis for characterization of flow coefficient, an analytical model has been established for a simplified geometry. This model has been corrected corresponding to more complex valve geometries, utilizing the results of axisymmetric quasi-3D (Q3D) computations using the Computational Fluid Dynamics (CFD) code FLUENT. By this means, a semi-empirical modelling methodology has been elaborated for characterization of through-flow behavior of pneumatic valves of various geometries

Szabályzott pneumatikus rendszerek dinamikai vizsgálata = Dynamic Investigation on Controlled Pneumatic Systems

A projekt során kialakítottunk AMESim környezetben egy olyan modellezési módszertant és egydimenziós szimulációs eszközt, amelynek révén szabályozott pneumatikus rendszerek, így pl. haszongépjármű-fékrendszerek dinamikai viselkedése vizsgálható, és az egyes fejlesztési módosítások, paraméter-változtatások hatása hatékonyan nyomon követhető. A szelepáramlás részleteinek feltérképezésére, az egydimenziós modell pontosítására FLUENT szimulációt alkalmaztunk. A szimulációs modellek alkalmasságát általunk kiépített kísérleti berendezésen végzett mérésekkel ellenőriztük, és mérések révén állapítottuk meg egyes bizonytalan paraméterek ? pl. szelep-átfolyási számok ? értékeit is. A kísérletileg validált szimulációs modellek segítségével mérnöki irányvonalakat nyertünk arra vonatkozóan, hogyan kell bizonyos rendszerelemek paramétereit ? pl. szeleptest-tömegeket, flexibilis tömítések anyagjellemzőit ? megváltoztatni annak érdekében, hogy a rendszerelem továbbra is ellássa feladatát, de a káros rezonancia-jellemzők elkerülhetőek legyenek. Ezáltal a rendszerelemek élettartama jelentősen feljavítható, a pneumatikus rendszer üzemvitele megbízhatóvá válik, és elkerülhetőek a felhasználó által reklamált rezgések és zajhatások. A projekt eredményeit pneumatikus jármű-fékrendszerek fejlesztésében hasznosítottuk. | During the project, a modelling methodology and a one-dimensional simulation tool has been established in AMESim environment, by means of which the dynamic behaviour of controlled pneumatic systems ? such as the brake systems of commercial vehicles ? can be examined, and the effect of modifications, parameter changes can be effectively studied during the R&D of the related systems. In order to survey the flow details in the pneumatic components and to make the one-dimensional model more accurate, FLUENT flow simulation has been applied. The simulation models have been validated by comparing the simulation results with measurement data obtained in an in-house built experimental facility. Measurements were also carried out for identification of uncertain system parameters, such as flow coefficients of valves. On the basis of the experimentally validated simulation models, engineering guidelines have been established for modification of certain parameters of pneumatic components ? such as valve body mass, material characteristics of flexible seals etc. ? in order to obtain proper system operation while avoiding harmful resonance effects. By this means, the life cycle of the components can be elongated, the system operates reliably, and the vibration as well as noise reclaimed by the user can be eliminated. The results of the project have been utilised in development of pneumatic brake systems of vehicles

CFD simulation of a connected rotary piston expander - compressor system

In the current study a connected expander – compressor system is investigated. The system is a novel development of such systems to extract mechanical energy from low enthalpy sources, e.g. thermal water, geothermal sources. The system consists of an expander in which warm air expands and flows toward a compressor stage. The connection between the devices has a heat exchanger, thus cooled air is introduced to the compressor. After compression the flow exits the compressor at around atmospheric conditions. During the investigation the Computational Fluid Dynamics (CFD) model of this system is built. The heat exchange in the connecting duct is modelled as an idealised heat exchanger with no pressure loss and perfect efficiency. The aim of the investigation is to find out the flow related parameters and efficiency of the whole connected system with the help of CFD simulations

Gas Dynamic Pipe Flow Effects in Controlled Pneumatic Systems - A Simulation Study

Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is to ensure a controlled operating pressure modulated at a high accuracy and high temporal resolution. This paper reports a computational case study representing the influence of gas dynamic pipe flow effects on the operation of a pneumatic system to be controlled by means of an EPM. The simulation has been carried out with use of simulation software AMESim version 3.01. Given that no standard gas dynamic pipe model and electro-dynamically-relevant solenoid valve model are included in the present version of the simulation software, such models had to be elaborated by the authors. The simulation studies reveal that the self-developed gas dynamic pipe model resolves properly the wave effects and flow fluctuations expected from a realistic pneumatic pipe performing high velocity flow. The simulation must accurately resolve such phenomena if the computational study aims to provide an aid to the design of a proper pressure control loop. It has been concluded that a gas dynamic pipe model, covering reliably the physically possible entire Mach number range, is essential in simulation of pneumatic systems

Cooling jacket development for electric motors used in e-aircrafts

Most modern airplanes are powered with IC engines because electrical propulsion was not feasible at the dawn of powered flight. It became viable only recently due to advancements made on electric propulsion systems. Weight and space are key factors for airplanes. Increasing the power density of the engine can enable the design of more efficient and more powerful planes. One way to achieve this is to increase the power level of the electric motor which also increases the power loss. In this case more efficient cooling is needed to remove the excess heat. The aim of this paper is to determine the optimal cooling solution for the stator of a radial flux permanent magnet (PM) electric motor which is installed in an electric airplane. Computational fluid dynamics (CFD) is used for the comparison of the developed concepts and their sub-concepts. The results are detailed for every initial concept and then the three best designs are chosen for further optimisation. Most modern airplanes are powered with IC engines because electrical propulsion was not feasible at the dawn of powered flight. It became viable only recently due to advancements made on electric propulsion systems. Weight and space are key factors for airplanes. Increasing the power density of the engine can enable the design of more efficient and more powerful planes. One way to achieve this is to increase the power level of the electric motor which also increases the power loss. In this case more efficient cooling is needed to remove the excess heat. The aim of this paper is to determine the optimal cooling solution for the stator of a radial flux permanent magnet (PM) electric motor which is installed in an electric airplane. Computational fluid dynamics (CFD) is used for the comparison of the developed concepts and their sub-concepts. The results are detailed for every initial concept and then the three best designs are chosen for further optimisation

Development of air-cooling concepts for electric motor used in electric aircrafts

Nowadays, due to the more and more important environmental issues and strict emission regulations, the electric vehicles are becoming popular and appearing in each type of transport, also in the aircraft industry. In this field, light weight, compact size, high power, and efficiency are the major design aspects. These criteria cause higher power density, thus the losses generated by the active parts are concentrated in a smaller volume. To handle the high thermal load, heat has to be effectively removed. The aim of this article is to improve the air-cooling system of a radial flux electric motor with the help of computational fluid dynamics (CFD) simulation. The stator is cooled by a water jacket, and the rotor is cooled by air in the closed housing. Several closed concepts are examined, with the different rotor and housing geometry. During the simulations, motor with a full load at maximal rotating speed is modelled. The results are compared with the base motor in the aspects of the critical parts’ temperature, cooling performance, losses, weight, and manufacturability. More than 40 °C magnet temperature reduction can be reached with geometry modification on the housing

A sejtek közti kommunikáció újonnan azonosított mikrovezikulum-útjának vizsgálata = Analysis of cell-derived microvesicles that represent novel players in intercellular communication

Munkánk során az extracelluláris vezikulák izolálásának és detektálásának számos meghatározó preanalitikai és analitikai paraméterére hívtuk fel a figyelmet. Elsőként mutattunk rá, hogy a mikrovezikulák és a fehérje-aggregátumok biofizikai paraméterei jelentős mértékben átfednek, és ez zavarhatja a mikrovezikulák mérését. Kidolgoztuk annak módszerét, hogy egyazon biológiai forrásból származó különböző vezikula populációkat párhuzamosan, nagy mennyiségben, intakt formában tudjunk izolálni. Összehasonlító proteomikai elemzést végeztünk thymus eredetű apoptotikus testek és mikrovezikulák esetében. Számos T sejt jelátvitelben és immunfolyamatokban szerepet játszó fehérjét és autoantigént azonosítottunk. Igazoltuk, hogy T sejt eredetű citokinek és extracelluláris vezikulák együttes hatását monociták génexpressziójára. Igazoltuk, hogy a mikrovezikulák önálló ionháztartással rendelkeznek. Kimutattuk, hogy thymocyta exoszómák nem tartalmaznak riboszómális RNS-eket, azonban feldúsulnak bennük kis RNS-ek (pl. bizonyos miRNS-ek). Polymyositises betegekben emelkedett keringő mikrovezikula számot mutattunk ki, mely korrelált a betegség bizonyos klinikai paramétereivel. Végül elsőként igazoltuk, hogy egészséges T sejt eredetű mikrovezikulák CD62P-CD161 kölcsönhatás révén specifikusan kötődnek monociták felszínéhez. | In our work we drove attention to several pre-analytical and analytical parameters affecting isolation and detection of work extracellular vesicles. We were the first to describe that microvesicles share biophysical parameters with protein aggregates which may confound microvesicle assessment by flow cytometry. We developed protocols for the isolation of large amounts of intact vesicle types secreted simultaneously by the same biological source. We carried comparative proteomic analysis of murine thymus derived apoptotic bodies and microvesicles. We identified large number of proteins involved in T cell signaling or immune functions as well as autoantigens within these structures. We provided evidence fro crosstalk between T cell derived extracellular vesicles and cytokines on the gene expression of monocytes. We have shown that microvesicles possess autonomous ion homeostasis. We found that thymocyte derived exosomes lacked the 18S and 28S ribosomal RNA molecules, while they were enriched in small RNA species (e.g. certain miRNAs). We described that patients with polyomyelitis were characterized by elevated levels of circulating microvesicle. Monocyte- and B cell-derived microvesicle numbers correlated with certain clinical parameters of the diseases. Finally, for the first time we showed that HLA-G+, trophoblast-derived microvesicles isolated from healthy pregnant blood plasma samples, bound specifically to T cells via CD62P-CD161 interaction, and induced STAT3 phosphorylation

MetaAsso: an approach for quality

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro , 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Effects of RAMEA-complexed polyunsaturated fatty acids on the response of human dendritic cells to inflammatory signals

The n−3 fatty acids are not produced by mammals, although they are essential for hormone synthesis and maintenance of cell membrane structure and integrity. They have recently been shown to inhibit inflammatory reactions and also emerged as potential treatment options for inflammatory diseases, such as rheumatoid arthritis, asthma and inflammatory bowel diseases. Dendritic cells (DC) play a central role in the regulation of both innate and adaptive immunity and upon inflammatory signals they produce various soluble factors among them cytokines and chemokines that act as inflammatory or regulatory mediators. In this study we monitored the effects of α-linoleic acid, eicosapentaenoic acid and docosahexaenoic acid solubilized in a dimethyl sulfoxide (DMSO)/ethanol 1:1 mixture or as complexed by randomly methylated α-cyclodextrin (RAMEA) on the inflammatory response of human monocyte-derived dendritic cells (moDC). The use of RAMEA for enhancing aqueous solubility of n−3 fatty acids has the unambiguous advantage over applying RAMEB (the β-cyclodextrin analog), since there is no interaction with cell membrane cholesterol. In vitro differentiated moDC were left untreated or were stimulated by bacterial lipopolysaccharide and polyinosinic:polycytidylic acid, mimicking bacterial and viral infections, respectively. The response of unstimulated and activated moDC to n−3 fatty acid treatment was tested by measuring the cell surface expression of CD1a used as a phenotypic and CD83 as an activation marker of inflammatory moDC differentiation and activation by using flow cytometry. Monocyte-derived DC activation was also monitored by the secretion level of the pro- and anti-inflammatory cytokines IL-1β, TNF-α, IL-6, IL-10 and IL-12, respectively. We found that RAMEA-complexed n−3 fatty acids reduced the expression of CD1a protein in both LPS and Poly(I:C) stimulated moDC significantly, but most efficiently by eicosapentaenic acid, while no significant change in the expression of CD83 protein was observed. The production of IL-6 by LPS-activated moDC was also reduced significantly when eicosapentaenic acid was added as a RAMEA complex as compared to its DMSO-solubilized form or to the other two n−3 fatty acids either complexed or not. Based on these results n−3 fatty acids solubilized by RAMEA provide with a new tool for optimizing the anti-inflammatory effects of n−3 fatty acids exerted on human moDC and mediated through the GP120 receptor without interfering with the cell membrane structure