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141.
The group of special (or proper) orthogonal matrices, SO(N), is used throughout engineering mechanics in the analysis and representation of mechanical systems. In this paper, a solution
is presented for the optimal transformation between two elements of SO(N). The transformation is assumed to occur during a specified finite time, and a cost function that penalizes the transformation
rates is utilized. The optimal transformation is found as a constant-rate rotation in each of the principal planes relating
the two elements. Although the kinematics of SO(N) are nonlinear and governed by Poisson’s equation, the solution is found to be a linear function of the generalized principal
angles. This is made possible by the extension of principal-rotation kinematics from three-dimensional rotations to the general
SO(N) group. This extension relates the N-dimensional angular velocity to the derivatives of the principal angles. The cost of the optimal transformation, the square
root of the sum of the principal angles squared, also provides a useful measure for the angular distance between two elements
of SO(N). 相似文献
142.
Improvements to a large neighborhood search heuristic for an integrated aircraft and passenger recovery problem 总被引:1,自引:0,他引:1
Karine Sinclair Jean-François Cordeau Gilbert Laporte 《European Journal of Operational Research》2014
Because most commercial passenger airlines operate on a hub-and-spoke network, small disturbances can cause major disruptions in their planned schedules and have a significant impact on their operational costs and performance. When a disturbance occurs, the airline often applies a recovery policy in order to quickly resume normal operations. We present in this paper a large neighborhood search heuristic to solve an integrated aircraft and passenger recovery problem. The problem consists of creating new aircraft routes and passenger itineraries to produce a feasible schedule during the recovery period. The method is based on an existing heuristic, developed in the context of the 2009 ROADEF Challenge, which alternates between three phases: construction, repair and improvement. We introduce a number of refinements in each phase so as to perform a more thorough search of the solution space. The resulting heuristic performs very well on the instances introduced for the challenge, obtaining the best known solution for 17 out of 22 instances within five minutes of computing time and 21 out of 22 instances within 10 minutes of computing time. 相似文献
143.
Chung CJ Lee SC Groves JR Brower EN Sinclair R Clemens BM 《Physical review letters》2012,108(10):106102
Recently, a large increase in the equilibrium hydrogen pressure has been reported for MG thin films capped with a Pd layer. We show that this increase is due to intermixing of Mg and Pd, as opposed to a strain effect as previously claimed. Transmission electron microscopy and depth profiling x-ray photoemission spectroscopy are used to directly measure interfacial intermixing between Mg and Pd, and we find that intermixing and equilibrium hydrogen pressure both increase with annealing. We present a thermodynamic model of the effect of alloying on equilibrium pressure, and find that the observed equilibrium pressure increase is consistent with the observed thickness of the intermixed region, which is of the order of a few nm. We also show that stress measured during hydrogenation corresponds to a negligible increase in equilibrium pressure. 相似文献
144.
Kai Zhang O. Amponsah M. Arslan T. Holloway David Sinclair Wei Cao M. Bahoura A.K. Pradhan 《Journal of magnetism and magnetic materials》2012
The fabrication of condensed silica and mesoporous silica coated spinel CoFe2O4 and FeCo alloy magnetic nanocomposites are reported. The encapsulation of well-defined 5 nm thick uniform silica layer on CoFe2O4 magnetic nanoparticles was performed. The formation of mesopores in the shell was a consequence of removal of organic group of the precursor through annealing. The NiO nanoparticles were loaded into the mesoporous silica. The mesoporous silica shells leads to a larger coercivity than that of pure CoFe2O4 magnetic nanoparticles due to the decrease of interparticle interactions and magneto-elastic anisotropy. In addition, the FeCo nanoparticles were coated by condensed and mesoporous silica. The condensed silica can protect the reactive FeCo alloy from oxidation up to 300 °C. However, saturation magnetization of FeCo nanoparticles coated by silica after 400 °C annealing is dramatically decreased due to the oxidation of the FeCo core. The mesoporous silica coated magnetic nanostructure loaded with NiO as a final product could be used in the field of biomedical applications. 相似文献
145.
Sinclair J Granfeldt D Pihl J Millingen M Lincoln P Farre C Peterson L Orwar O 《Journal of the American Chemical Society》2006,128(15):5109-5113
We report that GABA(A) receptors in a patch-clamped biological cell form a short-term memory circuit when integrated with a scanning-probe microfluidic device. Laminar patterns of receptor activators (agonists) provided by the microfluidic device define and periodically update the data input which is read and stored by the receptors as state distributions (based on intrinsic multistate kinetics). The memory is discharged over time and lasts for seconds to minutes depending on the input function. The function of the memory can be represented by an equivalent electronic circuit with striking similarity in function to a dynamic random access memory (DRAM) used in electronic computers. Multiplexed biohybrid memories may form the basis of large-scale integrated biocomputational/sensor devices with the curious ability to use chemical signals including odorants, neurotransmitters, chemical and biological warfare agents, and many more as input signals. 相似文献
146.
Karatholuvhu MS Sinclair A Newton AF Alcaraz ML Stockman RA Fuchs PL 《Journal of the American Chemical Society》2006,128(39):12656-12657
The synthesis of (+/-)-histrionicotoxin has been achieved in just nine steps using a two-directional synthesis strategy. Key reactions include a two-directional cross-metathesis, a tandem oxime formation/Michael addition/1,4-prototopic shift/[3 + 2]-cycloaddition cascade, a selective Z,Z-bisenyne formation, and a one-pot N-O and bischloroacetylene reduction. 相似文献
147.
This paper demonstrates the use of micron sized beads, modified with fluorescent dyes, as non-invasive sensors to probe the local changes in pH, within a microfluidic channel. To achieve this, amine modified polystyrene spheres (either 3 microm or 6 microm in diameter) were functionalised with the pH sensitive fluorochrome SNARF-1 to produce point sensors. The modified beads were trapped at defined positions close to a pair of integrated planar gold microelectrodes within the channel, using optical tweezers. Both transient and steady-state electrochemical potentials were applied to the microelectrode pair in order to generate changes in the local pH, associated with electrolysis. The functionalised beads indicated the pH changes in the channel, measured as a change in the fluorescence signal, generated by the immobilised pH sensitive dye. Responses were measured with temporal resolutions of between 1 and 200 ms, whilst the spatial resolution of the pH gradients was limited by the size of the beads to 3 microm. 相似文献
148.
149.
Barry Johnson made major contributions to the theory of Banachalgebras, by stimulating research on automatic continuity andcohomology in these algebras. His research on the continuousHochschild cohomology of Banach and operator algebras led tomajor developments in these areas, and to a recognition of amenabilityas more than simply a group-theoretic idea, but also one thatis widely applicable in modern analysis. 相似文献
150.
R. Sinclair 《Few-Body Systems》1995,18(1):41-50
The Laughlin variational wave function of a quantum liquid used in studying the fractional quantum Hall effect may be interpreted
as a two-dimensional system of particles interacting via a logarithmic interaction, with a centripetal force proportional
to the square of the distance from the origin. We present exact calculations of the partition function, radial distribution
function, and particle density for systems of up to six particles.
Received April 25, 1994; revised August 5, 1994; accepted for publication August 30, 1994 相似文献