17 resultados para octahedral tilting

em Deakin Research Online - Australia


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The current automotive industry and todays car drivers are faced with every increasing challenges, not previously experienced. Climate Change, financial issues, rising fuel prices, increased traffic congestion and reduced parking space in cities are all leading to changes in consumer preferences and the requirements of modern passenger vehicles. However, despite the shift in the industry dynamics, the principal layout of a car hasn’t changed since its invention. The design of a ’conventional’ vehicle is still principally a matchbox with four wheels, one at each corner. The concept has served its purpose well for over 100 years, but such a layout is not suited to solving today’s problems. To address the range of problems faced by the industry, a number of alternative commuting vehicles have been developed. Yet the commercialization of these ‘alternative’ vehicles has yet to be successful. This is largely due failure of these vehicles to meet the changing demands of the industry and the limited understanding of consumer behaviour, motivation and attitudes. Deakin University’s Tomorrow’s Car concept tackles all of these problems. The vehicle is a novel three-wheeler cross over concept between a car and a motorbike that combines the best of both worlds. The vehicle combines the low cost, small size and ‘fun’ factor of a motorbike together with the safety, comfort and easy to drive features of a car produce a vehicle with a fuel efficiency better than either car or scooter. Intensive market research has been conducted for various major potential markets of alternative vehicles including India, China and Australia. The research analysed consumer attitudes in relation to narrow tilting vehicles, and in particular towards Deakin’s Tomorrow’s Car (TC). The study revealed that a relatively large percentage of consumers find such a concept very appealing. For the other consumers, the overall appearance and perception of safety and not the actual safety performance were found to be the most impeding factors of such vehicles. By addressing these issues and marketing the vehicle accordingly the successful commercialization of Tomorrow’s Car can be ensured.

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A novel 6-DOF parallel kinematic manipulator named the Octahedral Hexarot is presented and analyzed. It is shown that this manipulator has the important benefits of combining a large positional workspace in relation to its footprint with a sizable range of platform rotations. These features are obtained by combining a rotation-symmetric actuating arm system with links in an octahedral-like configuration. Thus the manipulator consists of a central cylindrical column with six actuated rotating upper arms that can rotate indefinitely around the central column. Each upper arm is connected to a manipulated platform by one 5-DOF lower arm link. The link arrangement of the Octahedral Hexarot is inspired by the original Gough platform. The manipulated platform is an equilateral triangle and the joint positions on the upper arms approximately form an equilateral triangle. A task dependent optimization procedure for the structural parameters is proposed and the workspace of the resulting manipulator is analyzed in depth.

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The synthesis of a centrally functionalized, ribbon-shaped [6]polynorbornane ligand L that self-assembles with PdII cations into a (Pd2L4) coordination cage is reported. The shape-persistent (Pd2L4) cage contains two axial cationic centers and an array of four equatorial H-bond donors pointing directly towards the center of the cavity. This precisely defined supramolecular environment is complementary to the geometry of classic octahedral complexes [M(XY)6] with six diatomic ligands. Very strong binding of [Pt(CN)6]2- to the cage was observed, with the structure of the host-guest complex ([Pt(CN)6]@Pd2L4) supported by NMR spectroscopy, MS, and X-ray data. The self-assembled shell imprints its geometry on the encapsulated guest, and desymmetrization of the octahedral platinum species by the influence of the D4h-symmetric second coordination sphere was evidenced by IR spectroscopy. [Fe(CN)6]3- and square-planar [Pt(CN)4]2- were strongly bound. Smaller octahedral anions such as [SiF6]2-, neutral carbonyl complexes ([M(CO)6]; M=Cr, Mo, W) and the linear [Ag(CN)2]- anion were only weakly bound, showing that both size and charge match are key factors for high-affinity binding.

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The molecular structure of the centrosymmetric hexanuclear title compound, [iPrSn(O)(O2CCH3)]6·4CHCl13 or [Sn6O6(C3H7)6(C2H3O2)6]·4CHCl3, adopts the `drum' motif, in which two (iPrSnO)3 caps are linked via six μ3-oxo atoms and six acetate groups. The Sn atoms are in distorted octahedral environments, defined by a CO5 donor set for each of the three independent Sn atoms.

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The centrosymmetric hexanuclear title compound, hexa-μ2-acetato-hexa-μ3-oxo-hexakis[(trimethylsilylmethyl)tin], [Sn6O6(C2H3O2)6(C4H11Si)6], adopts a 'drum' structure in which two [(Me3SiCH2)SnO]3 caps are linked to each other via six μ3-O atoms and six bidentate bridging acetate groups. A CO5 donor set defines a distorted octahedral environment for each of the three independent Sn atoms.

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The complexes [Hpy][Cu(H3L)(H2O)] 1 (L6 = nitrilotrimethylenetrisphosphonate) and [Cu(HL°)(py)]2·2Me2CO 2 [(L°)3 = P,P,P" -triphenylnitrilotrismethylenetrisphosphinate)] have been isolated and characterized by X-ray crystallography, near IR-visible spectroscopy and magnetic measurements. The structure determination has shown the complexes to be constituted by monomeric and dimeric units respectively. In the monomer the metal atom is surrounded by the phosphonate ligand and a water molecule, with a geometry between a trigonal bipyramid and a square pyramid. The two copper atoms in the dimer are held together by an arm of the tripod ligand, with a pyridine molecule as additional ligand, and display octahedral geometry. The presence of monomeric and dimeric species in aqueous solutions of 1 and 2 has been shown by ESMS studies. The formation in water solution of the dimer [{Cu(H3L)}2]2-, as a minor species, has been supported by potentiometric measurements, whereas only the monomeric anion [CuL°] has been ascertained to be present. In general the ligand H3L° forms less stable copper(II) complexes than H6L.


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The present study analyzes the morphological transformations of reaction products i.e., MgO, MgAl2O4 occurring during the reaction between SiO2 and Al-Mg alloy in Al-Mg-SiO2 composite processed by the liquid metallurgy technique. Different phases of platelet and hexagonal morphologies are detected and their composition analysis by EDS has confirmed them as being transition phases existing between MgO, MgAl2O4 and Al2O3. This study has also revealed the gradual transformation of (i) MgO needles to octahedral MgAl2O4 through Mg-Al-Si-O and Mg-Al-O transition phases having platelet morphologies and (ii) MgAl2O4 to Al2O3 through hexagonal transition phases on holding of Al-5Mg-SiO2 and Al-1Mg-SiO2 composites respectively at 1023K. Fully developed α-Al2O3 crystals are not observed under the present experimental conditions, wherein the Mg content is well above the equilibrium Mg content required for the formation of stable Al2O3 (<0.05 wt. %).

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27Al, 31P and 7Li NMR measurements have been performed on lithium conducting ceramics based on the LiTi2(PO4)3 structure with Al, V and Nb metal ions substituted for either Ti or P within the framework NASICON structure. The 27Al magic angle spinning NMR measurements have revealed that, although Al is intended to substitute for octahedral Ti sites, additional substitution into tetrahedral environments (presumably phosphorous sites) occurs with increasing amount of Al addition. This tetrahedral substitution appears to occur more readily in the presence of vanadium, in Li1+xAlxTi2−x(PO4)2.9(VO4)0.1, whereas similar niobium additions (in place of vanadium) appear to stifle tetrahedral substitution. 7Li static NMR spectra reveal quadrupolar structure with Cq approximately 42 kHz, largely independent of substitution. Measurement of the 7Li central transition linewidth at room temperature reveals a relatively mobile lithium species (300–900 Hz) with linewidth tending to decrease with Al substitution and increase with increasing V or Nb. This new structural information is discussed in the context of ionic conduction in these ceramics.

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Motorbike riders are 34-times more likely to die in a crash compared to car drivers per km travelled (1). Such safety risks together with special skill requirements for the driver and much lower comfort compared to normal cars are the main reasons why motorbikes represent only a fraction of all vehicle sales in developed countries. Deakin University is developing a revolutionary cross-over fun vehicle with ultra low fuel consumption and emissions. This new vehicle generation combines the best of two worlds: the fun to drive, low cost, and small size of a scooter together with the safety, comfort and easiness to operate of a car. The result is a vehicle that is more fuel efficient than most cars or even scooters.

Various tilting cross over vehicles have been presented over the last decade that were trying to automate the tilting control of narrow vehicles to make them safer. Examples of these concepts are the Carver, Clever and in some way also the MP3 scooter from Piaggio. The problem with fully enclosed concepts like the Carver or Clever is that they require very complex and therefore also expensive tilting control systems so that the vehicles are not price competitive compared to low cost micro cars or even normal small cars. The MP3 on the other hand comes with a tilting control system which is only semi automatic so that typical car advantages - comprehensive safety features like crush zones, roll over protection, air bags, safety belts or comfort features like full weather protection including heating and cooling – can not be provided.

Deakin’s approach is quite different to the above mentioned concepts. The requirements were derived based on two different investigations: The first step was a critical evaluation of social trends and the second step was an in-depth benchmarking study of existing concepts which identified the typical strengths and weaknesses of these concepts. In a critical next step a new concept was created that addresses most of the weaknesses of existing tilting three-wheelers in a holistic approach by setting clear priority rankings for the vehicle targets, based on current trends. The priorities were set in the following order: Safety, Affordability, Fun and Efficiency (SAFE).

The key feature that enables an enclosed tilting vehicle is a fully automatic tilting control system. With an automatic tilting control system the driver does not need to put the feet on the ground to balance the vehicle when he stops, so the vehicle can be built with a full enclosure. This allows the implementation of typical car like safety features (seat belts, roll over structure, crush zones, air bags). The SafeRide™ tilting control system is a passive system that involves the driver’s balancing sense in its feedback control system. The vehicle has typical scooter like steering characteristics, where the steering is initiated through countersteering. Another safety critical design feature is the crush zone between the two front wheels which is not possible with only one front wheel or with the powertrain positioned between the front wheels, as the powertrain can’t absorb a lot of energy due to its structural stiffness and density. The passive tilting control system is quite simple and therefore makes the vehicle very affordable, an important factor for successful commercialisation.

Another advantage of integrating the human balancing senses in the feedback control of the tilting system is that the system kicks in slightly after the human balancing reacts. In some instances that can generate the typical adrenalin thrill known from riding a bike. This fun factor is quite common with many trend sports like mountain biking, surfing, roller-skating, snowboarding, or skateboarding. Some of these sports have seen very rapid growth only a short time after they have been invented. Utilising the human balancing system during driving also makes the vehicle safer as the adrenalin is produced after reaching a semi-stable driving condition that is controlled by the vehicles tilting control system, but before the vehicle reaches an unstable driving condition that can not be controlled by the vehicle but only (eventually) by the driver – if he has got the required driving skill and if he is alert enough.

Efficiency superior to most cars and scooters is achieved by the aerodynamics of a fully enclosed body structure in combination with the small frontal area of a typical scooter and the droplet shape enabled by the relatively wide front with 2 wheels and the very narrow tail with only one rear wheel. The passive tilting system also contributes to the extreme efficiency as the system only draws some small electrical power for the electronic control unit. Another feature is a low cost exhaust energy recovery system which is discussed in another paper.

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Layered oxides of Sr4Fe4Co2O13 (SFC2) which contains alternating perovskite oxide octahedral and polyhedral oxide double layers are attractive for their mixed ionic and electronic conducting and oxygen reduction reaction properties. In this work, we used the EDTA–citrate synthesis technique to prepare SFC2 and vary the calcination temperature between 900 and 1100 _C to obtain SFC2, containing different phase content of perovskite (denoted as SFC-P) and (Fe,Co) layered oxide phases (SFC-L). Rietveld refinements show that the SFC-P phase content increased from _39 wt% to _50 wt% and _61 wt% as the calcination temperature increased from 900 _C (SFC2-900) to 1000 _C (SFC2-1000) and 1050 _C (SFC2-1050). At 1100 _C (SFC2-1100), SFC-P became the dominant phase. The oxygen transport properties (e.g. oxygen chemical diffusion coefficient and oxygen permeability), electrical conductivity and oxygen reduction reaction activity is enhanced in the order of SFC2-1000, SFC2-1100 and SFC2-1050. The trend established here therefore negates the hypothesis that the perovskite phase content correlates with the oxygen transport property enhancement. The results suggest instead that there is an optimum composition value (e.g. 61 wt% of SFC-L for SFC2-1050 in this work) on which synergistic effects take place between the SFC-P and SFC-L phase.

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A new stable aluminum aminoterephthalate system contains octameric building blocks that are connected by organic linkers to form a 12-connected net (see picture). The structure adopts a cubic centered packing motive in which octameric units replace individual atoms, thus forming distorted octahedral (red sphere) and tetrahedral cages (green spheres) with effective accessible diameters of 1 and 0.45 nm, respectively

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The present work investigated the evolution of strain-induced NbC precipitates in a model austenitic Fe-30Ni-Nb steel deformed at 925 °C to a strain of 0.2 during post-deformation holding between 3 and 1000 s and their effect on the reloading flow stress. The precipitate particles preferentially nucleated on the nodes of the periodic dislocation networks constituting microband walls. Holding for 10 s resulted in the formation of fine, largely coherent NbC particles with a mean diameter of ∼5 nm, which displayed a cube-on-cube orientation relationship with austenite and caused the maximum increase in the reloading steady-state flow stress. A further increase in the holding time from 30 to 1000 s led to the formation of semi-coherent, gradually coarser and more widely spaced particles with a mean diameter of 8 nm and above, which led to a gradual decrease in the reloading steady-state flow stress. The holding time increase resulted in progressive disintegration of the dislocation substructure and dislocation annihilation through static recovery processes, which was also reflected by the measured softening fractions. The precipitate particle shape changed during post-deformation annealing from elliptical to faceted octahedral and subsequently to tetra-kai-decahedral. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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The crystal-chemistry of a series of synthetic Al-Fe3+ smectites was studied in detail using near and mid infrared spectroscopy. Chemical and NIR data indicated a quite complete range of octahedral Al for Fe3+ substitution, and therefore, the solid-solution between beidellite and nontronite end-members was continuous and complete. The wavenumbers of several infrared absorption bands were correlated with the chemistry of the synthetic smectites, providing a useful tool to constrain their structural formulae and also for assisting in assignments of similar bands in natural smectites. The Al and Fe3+ cations were shown to be randomly distributed in the octahedral sheet of synthesized smectites. Despite the high availability of iron during synthesis, generally only a small amount of tetrahedral Fe3+ was observed.