Simulation of Micro-Electronic FlowFET Systems

A microelectronic fluidic system has been investigated by modeling and 3D simulation of fluid flow controlled by an applied gate voltage. The simulations have helped to characterize a novel FlowFET (a fluidic Field Effect Transistor) device under fault-free conditions. The FlowFET operates by applying a voltage field from a gate electrode in the insulated side wall of a microchannel to modulate the ␣-potential at the shear plane [1]. The change in ␣-potential can be used to control both the magnitude and direction of the electroosmotic flow in the microchannel

Near-infrared colors of minor planets recovered from VISTA - VHS survey (MOVIS)

The Sloan Digital Sky Survey (SDSS) and Wide-field Infrared Survey Explorer (WISE) provide information about the surface composition of about 100,000 minor planets. The resulting visible colors and albedos enabled us to group them in several major classes, which are a simplified view of the diversity shown by the few existing spectra. We performed a serendipitous search in VISTA-VHS observations using a pipeline developed to retrieve and process the data that corresponds to solar system objects (SSo). The colors and the magnitudes of the minor planets observed by the VISTA survey are compiled into three catalogs that are available online: the detections catalog (MOVIS-D), the magnitudes catalog (MOVIS-M), and the colors catalog (MOVIS-C). They were built using the third data release of the survey (VISTA VHS-DR3). A total of 39,947 objects were detected, including 52 NEAs, 325 Mars Crossers, 515 Hungaria asteroids, 38,428 main-belt asteroids, 146 Cybele asteroids, 147 Hilda asteroids, 270 Trojans, 13 comets, 12 Kuiper Belt objects and Neptune with its four satellites. The colors found for asteroids with known spectral properties reveal well-defined patterns corresponding to different mineralogies. The distributions of MOVIS-C data in color-color plots shows clusters identified with different taxonomic types. All the diagrams that use (Y-J) color separate the spectral classes more effectively than the (J-H) and (H-Ks) plots used until now: even for large color errors (<0.1), the plots (Y-J) vs (Y-Ks) and (Y-J) vs (J-Ks) provide the separation between S-complex and C-complex. The end members A, D, R, and V-types occupy well-defined regions.Comment: 19 pages, 16 figure

Parametric FEM simulation of composite barrier FTJs under external bias at room temperature

A study on a parametrized model of a composite barrier FTJ (three-interface system, with a non-polar dielectric layer) under an external bias voltage and at room temperature, using FEM-based simulations, was performed. The approach involves the Thomas-Fermi model assuming incomplete screening of polarization charges for building the energy barrier profile, and numerically simulates the electron transport through the barrier by bias-voltage-dependent tunneling, using Tsu-Esaki formulation. That naturally include the temperature dependent contributions to the total current density. The TER coefficient and current densities are computed considering variation of a large set of parameters that describe the composite barrier FTJ system in realistic physical range of values with respect to a reference (prototypical) system. In this study, the parametric simulations were performed starting from selected data reported on the SRO/STO/BTO/SRO heterostructure. The most important results of our work can be stated as follows: i) The FEM simulations prove to be reliable approach when we are interested in the prediction of FTJ characteristics at temperatures close to 300 K, and ii) We show that several configurations with large TER values may be predicted, but at the expense of very low current densities in the ON state. We suggest that the results may be useful for assessing the FTJ performances at ambient temperature, as well as to design preoptimized FTJs by using different combinations of materials to comply with a set of properties of a specific model

THEORETICAL ASPECTS OF THE AERATION DRYING PROCESS WITH APPLICATION IN THE HAY TECHNOLOGY

In the current context of the development of mechanized agriculture in several directions in the field of feed storage needs appear in the effective implementation of the drying method used. In terms of maintaining higher production achieved by reducing losses of fodder harvesting and secondly by increasing the number of cycles of harvest due to reduced time of harvest (representing the time elapsed mowing fodder plant and to store hay), outline the need for a more careful study of the drying process. This paper presents some theoretical aspects that determine and control the drying process used in technology of hay

Modeling of Micro-Electronic Fluidic Systems

A microelectronic fluidic system is studied using modeling and simulation of fluid flow controlled by applying gate voltage. 2D simulations were used to characterize the fluidic Field Effect Transistor (FlowFET) device under fault-free conditions. The FlowFET operates by applying a voltage from a gate electrode in the insulated side wall of a microchannel, to modulate the z-potential at the shear plane. The change in z-potential can be used to control both the magnitude and the direction of the electroosmotic flow in the microchannel

Optimizing end-labeled free-solution electrophoresis by increasing the hydrodynamic friction of the drag-tag

We study the electrophoretic separation of polyelectrolytes of varying lengths by means of end-labeled free-solution electrophoresis (ELFSE). A coarse-grained molecular dynamics simulation model, using full electrostatic interactions and a mesoscopic Lattice Boltzmann fluid to account for hydrodynamic interactions, is used to characterize the drag coefficients of different label types: linear and branched polymeric labels, as well as transiently bound micelles. It is specifically shown that the label's drag coefficient is determined by its hydrodynamic size, and that the drag per label monomer is largest for linear labels. However, the addition of side chains to a linear label offers the possibility to increase the hydrodynamic size, and therefore the label efficiency, without having to increase the linear length of the label, thereby simplifying synthesis. The third class of labels investigated, transiently bound micelles, seems very promising for the usage in ELFSE, as they provide a significant higher hydrodynamic drag than the other label types. The results are compared to theoretical predictions, and we investigate how the efficiency of the ELFSE method can be improved by using smartly designed drag-tags.Comment: 32 pages, 11 figures, submitted to Macromolecule

Investigation of the Effect of a Diamine-Based Friction Modifier on Micropitting and the Properties of Tribofilms in Rolling-Sliding Contacts

The effect of N-Tallow-1,3-DiaminoPropane (TDP) on friction, rolling wear and micropitting has been investigated with the ultimate objective of developing lubricants with no or minimal environmental impact. A Mini Traction Machine (MTM-SLIM) has been utilised in order to generate tribofilms and observe the effect of TDP on anti-wear tribofilm formation and friction. Micropitting was induced on the surface of specimens using a MicroPitting Rig (MPR). The X-ray Photoelectron Spectroscopy (XPS) surface analytical technique has been employed to investigate the effect of TDP on the chemical composition of the tribofilm while Atomic Force Microscopy (AFM) was used to generate high resolution topographical images of the tribofilms formed on the MTM discs. Experimental and analytical results showed that TDP delays the Zinc DialkylDithioPhosphate (ZDDP) anti-wear tribofilm formation. TDP in combination with ZDDP induces a thinner and smoother anti-wear tribofilm with a modified chemical structure composed of mixed Fe/Zn (poly)phosphates. The sulphide contribution to the tribofilm and oxygen-to-phosphorous atomic concentration ratio are greater in the bulk of the tribofilm derived from a combination of TDP and ZDDP compared to a tribofilm derived from ZDDP alone. Surface analysis showed that utilising TDP effectively mitigates micropitting wear in the test conditions used in this study. Reduction of micropitting, relevant to rolling bearing applications, can be attributed to the improved running-in procedure, reduced friction, formation of a smoother tribofilm and modification of the tribofilm composition induced by TDP

Surface Fatigue Behaviour of a WC/aC:H Thin-Film and the Tribochemical Impact of Zinc Dialkyldithiophosphate

In wind turbine gearboxes, (near-)surface initiated fatigue is attributed to be the primary failure mechanism. In this work, the surface fatigue of a hydrogenated tungsten carbide/amorphous carbon (WC/aC:H) thin-film was tested under severe cyclic tribo-contact using PolyAlphaOlefin (PAO) and PAO + Zinc DialkylDithioPhosphate (ZDDP) lubricants. The film was characterised in terms of its structure and chemistry using X-ray diffraction, analytical Transmission Electron Microscopy (TEM) including Electron Energy Loss Spectroscopy (EELS), as well as X-ray Photoelectron Spectroscopy (XPS). The multilayer carbon thin-film exhibited promising surface fatigue performance showing a slight change in the hybridization state of the aC:H matrix. Dehydrogenation of the thin-film and subsequent transformation of cleaved C-H bonds to non planar sp2 carbon rings were inferred from EELS and XPS results. Whilst tribo-induced changes to the aC:H matrix were not influenced by a nanometer-thick ZDDP reaction-film, the rate of oxidation of WC and its oxidation state were affected. Whilst accelerating surface fatigue on a steel surface, the ZDDP-tribofilm protected the WC/aC:H film from surface fatigue. In contrast to the formation of polyphosphates from ZDDP molecules on steel surfaces, it appeared that on the WC/aC:H thin film surface ZDDP molecules decompose to ZnO suppressing the oxidative degradation of WC

TECHNICAL ASPECTS ON DYNAMIC BEHAVIOR OF THE SEMITRAILERS WITH SUSPENSION HITCH

An efficient means of transport, over short distances and heavy-duty traction on roads maintained or unmaintained field, agricultural land is considered system tractor - trailer. This article presents the results of experimental research on the dynamic behavior of the system tractor - trailer suspension system provided with agricultural roasted. The variety of constructive solutions for hitches with suspension motivated interest in experimental research of the effects caused by the introduction of elastic elements (leaf springs), fried farm semitrailer. They studied three variants of hitches compared with suspension and without suspension version. To highlight how it influenced the dynamic behavior of the studied system, were determined and analyzed for the following parameters: its spectrum of frequencies, maximum amplitude of vertical acceleration root mean square of the accelerations respectively

Ultraviolet and visible photometry of asteroid (21) Lutetia using the Hubble Space Telescope

The asteroid (21) Lutetia is the target of a planned close encounter by the Rosetta spacecraft in July 2010. To prepare for that flyby, Lutetia has been extensively observed by a variety of astronomical facilities. We used the Hubble Space Telescope (HST) to determine the albedo of Lutetia over a wide wavelength range, extending from ~150 nm to ~700 nm. Using data from a variety of HST filters and a ground-based visible light spectrum, we employed synthetic photometry techniques to derive absolute fluxes for Lutetia. New results from ground-based measurements of Lutetia's size and shape were used to convert the absolute fluxes into albedos. We present our best model for the spectral energy distribution of Lutetia over the wavelength range 120-800 nm. There appears to be a steep drop in the albedo (by a factor of ~2) for wavelengths shorter than ~300 nm. Nevertheless, the far ultraviolet albedo of Lutetia (~10%) is considerably larger than that of typical C-chondrite material (~4%). The geometric albedo at 550 nm is 16.5 +/- 1%. Lutetia's reflectivity is not consistent with a metal-dominated surface at infrared or radar wavelengths, and its albedo at all wavelengths (UV-visibile-IR-radar) is larger than observed for typical primitive, chondritic material. We derive a relatively high FUV albedo of ~10%, a result that will be tested by observations with the Alice spectrograph during the Rosetta flyby of Lutetia in July 2010.Comment: 14 pages, 2 tables, 8 figure