Experimental investigations of the effects of cutting angle on chattering of a flexible manipulator

When a machine tool is mounted at the tip of a robotic manipulator, the manipulator becomes more flexible (the natural frequencies are lowered). Moreover, for a given flexible manipulator, its compliance will be different depending on feedback gains, configurations, and direction of interest. Here, the compliance of a manipulator is derived analytically, and its magnitude is represented as a compliance ellipsoid. Then, using a two-link flexible manipulator with an abrasive cut off saw, the experimental investigation shows that the chattering varies with the saw cutting angle due to different compliance. The main work is devoted to finding a desirable cutting angle which reduces the chattering

Adhesive coating eliminated in new honeycomb-core fabrication process

Technique eliminates use of silicone-based adhesive material as bonding medium. Adhesive requires precise time-temperature cure. Prepreg resin is used as bonding medium, and each layer is laminated together to form honeycomb billet. Process can be used in any application where nonmetallic honeycomb core is being fabricated

The Interpersonal Foundations of Anti-Atheist Prejudice

Anti-atheist prejudice in the U.S. is socially accepted and rife—and not just because most Americans are religious. This research suggests that hostility toward atheists is related in part to protecting parental relationships. To the extent that they are established within parental relationships, shared reality theory implies that religious beliefs and associated attitudes will be psychologically defended to the extent that the parental relationships engaged are strong, healthy, and vital (Magee & Hardin, 2010; see also Hardin & Higgins, 1996). Three experiments examined the regulation of anti-atheist prejudice in the defense and protection of religious shared realities with parents, as implied by shared reality theory, and used parental attachment as an indicator of the strength and vitality of the parental relationship. The first two experiments explored parental attachment in the regulation of automatic anti-atheist prejudice during social interactions. In Experiment 1, automatic attitudes toward atheists were assessed with a subliminal sequential priming task in a social tuning paradigm in which the experimenter casually mentioned he was an atheist, or did not (e.g., Lowery et al., 2001). Interacting with an atheist reduced automatic anti-atheist prejudice among those with low parental attachment and, if anything, increased automatic anti-atheist prejudice among those with high parental attachment. Experiment 2 tested the causal role of parental attachment by experimentally manipulating parental attachment with an essay task and found complementary results: Interacting with an atheist reduced automatic anti-atheist prejudice among those with low manipulated parental attachment, increased automatic anti-atheist prejudice among those with high manipulated parental attachment, and did not affect automatic anti-atheist prejudice among those in a nonparental salience comparison condition. Experiment 3 manipulated the mere cognitive salience of the concept ‘atheist’ (in the absence of relationship demands) via a subliminal prime word task. Subliminal exposure to the word atheist reduced explicit anti-atheist prejudice among those with low parental attachment and low parental religious shared reality, but not among those with high parental attachment or high parental religious shared reality. This research suggests that when religious people interact with atheists (or think about atheists) anti-atheist prejudice is activated and then regulated by parental attachment

Extensive lava flow fields on Venus: Preliminary investigation of source elevation and regional slope variations

Large-volume lava flow fields have been identified on Venus, the most areally extensive of which are known as fluctus and have been subdivided into six morphologic types. Sheetlike flow fields (Type 1) lack the numerous, closely spaced, discrete lava flow lobes that characterize digitate flow fields. Transitional flow fields (Type 2) are similar to sheetlike flow fields but contain one or more broad flow lobes. Digitate flow fields are divided further into divergent (Types 3-5) and subparallel (Type 6) classes on the basis of variations in the amount of downstream flow divergence. As a result of our previous analysis of the detailed morphology, stratigraphy, and tectonic associations of Mylitta Fluctus, we have formulated a number of questions to apply to all large flow fields on Venus. In particular, we would like to address the following: (1) eruption conditions and style of flow emplacement (effusion rate, eruption duration), (2) the nature of magma storage zones (presence of neutral buoyancy zones, deep or shallow crustal magma chambers), (3) the origin of melt and possible link to mantle plumes, and (4) the importance of large flow fields in plains evolution. To answer these questions we have begun to examine variations in flow field dimension and morphology; the distribution of large flow fields in terms of elevation above the mean planetary radius; links to regional tectonic or volcanic structures (e.g., associations with large shield edifices, coronae, or rift zones); statigraphic relationships between large flow fields, volcanic plains, shields, and coronae; and various models of flow emplacement in order to estimate eruption parameters. In this particular study, we have examined the proximal elevations and topographic slopes of 16 of the most distinctive flow fields that represent each of the 6 morphologic types

InGaAsP/InP laser development for single-mode, high-data-rate communications

Materials studies as well as general and specific device development were carried out in the InGaAsP system. A comparison was made of three standard methods of evaluating substrate quality by means of dislocation studies. A cause of reduced yield of good wafers, the pullover of melt from one bin to the next, has been analyzed. Difficulties with reproducible zinc acceptor doping have been traced to segregation of zinc in the In/Zn alloy used for the doping source. Using EBIC measurments, the pn junction was shown to drift in location depending on factors not always under control. An analysis of contact structures by SIMS showed that the depth to which the sintered Au/Zn contact penetrates into the structure is typically 0.13 microns, or well within the cap layer and out of the p-type cladding and thus not deleterious to laser prformance. The problem of single-mode laser development was investigated and it was shown to be related to the growth habit over four different possible substrate configurations. The fabrication of constricted double heterojunctions, mesa stripe buried heterostructures, and buried heterostructures was discussed, and measurements were presented on the device properties of single-mode buried heterostructure lasers. Results include single spectral line emission at 3 mW and a threshold current of 60 mA

Enigmatic Sea Floor Mounds in Antarctica--analysis of bathymetry data from geophysical cruise NBP04-01

As part of the 2004 Nathaniel B. Palmer-0401 geophysical cruise, a structural geology enigma was identified on the Ross Sea floor off the Antarctica coast. Using multibeam bathymetry, a series of eight mysterious, “pepperoni-shaped” mounds were identified on the sea floor. My research entails the morphological study of these structures and the determination of their relationship to either nearby volcanism or subglacial features. Through the use of the IVS-Fledermaus© software program, bathymetric data obtained from the cruise was projected in a 3-dimensional model. Morphological data from the seafloor hills is compared to the attributes of glacial drumlins and volcanic tuya. Future work will include adding seismic and magnetic profiles of the area to the 3D model to constrain their composition and the internal subsurface structure associated with the hills. Once the origin of these features has been determined, a search for their existence in similar environments worldwide can be conducted in order to determine their uniqueness.Shell Oil Corp

Fluent temporal logic for discrete-time event-based models

Fluent model checking is an automated technique for verifying that an event-based operational model satisfies some state-based declarative properties. The link between the event-based and state-based formalisms is defined through fluents which are state predicates whose value are determined by the occurrences of initiating and terminating events that make the fluents values become true or false, respectively. The existing fluent temporal logic is convenient for reasoning about untimed event-based models but difficult to use for timed models. The paper extends fluent temporal logic with temporal operators for modelling timed properties of discrete-time event-based models. It presents two approaches that differ on whether the properties model the system state after the occurrence of each event or at a fixed time rate. Model checking of timed properties is made possible by translating them into the existing untimed framework. Copyright 2005 ACM

Dyke architecture, mineral layering, and magmatic convection; new perspectives from the Younger Giant Dyke Complex, S Greenland

The expedition was funded by the Mining Institute of Scotland Trust, the Institute of Materials, Minerals and Mining, the Society of Economic Geologists Hickok-Radford Fund, the Edinburgh Geological Society, the Augustine Courtauld trust and the Scott Polar Research Institute.Igneous sheet intrusions are a fundamental component of volcano plumbing systems. Identifying how sheet intrusion emplacement and geometry controls later magmatic processes is critical to understanding the distribution of volcanic eruptions and magma-related ore deposits. Using the Younger Giant Dyke Complex, a Mesoproterozoic suite of large (< 800 m wide) mafic dykes in southern Greenland, we assess the influence sheet of emplacement and geometry on subsequent magma flow and mush evolution. Through structural mapping, petrographic observations, and anisotropy of magnetic susceptibility fabric analyses, we show that the Younger Giant Dyke Complex was emplaced as a series of individual dyke segments, which following coalescence into a sheet intrusion remained largely isolated during their magmatic evolution. Through petrographic evidence for liquid-rich growth of cumulus phases, concentric magnetic fabrics, and the detailed study layered zones within the Younger Giant Dyke Complex, we infer magma convection occurred within the cores of each dyke element. We particularly relate layering to hydrodynamic sorting processes at a magma-mush boundary towards the base of each convection cell. Overall, our work demonstrates that the initial geometry of sheet intrusions can constrain magma flow patterns and affect the distribution of crystallisation regimes.Publisher PDFPeer reviewe