Spark (mathematics)

About: Spark (mathematics) is a research topic. Over the lifetime, 7304 publications have been published within this topic receiving 63322 citations.

Arc and spark spectra of ruthenium

Abstract: The direct-current arc and high-voltage spark spectra of ruth enium have been investigated for the purpose of compiling a comprehensive linc-list for forthcom in g t erm analyses of these spectra. These spectra were observed photographically with 30000, 15000 and 7,500 lines-pcr-in ch concave gratings in a vVadsworth m ountin g. Wavelengths 'and' estimated r elative intensities are presented for 6,000 lines in the spectra Ru I Ru II and Ru III in the wavelcngth range 2005.69 t o 11483.91 A. This list is compar~d with line l ists reported by other investigators.

Large-eddy simulation analysis of knock in a direct injection spark ignition engine:

Abstract: Downsized spark ignition engines running under high loads have become more and more attractive for car manufacturers because of their increased thermal efficiency and lower CO2 emissions. However, ...

A Distributed Frank-Wolfe Framework for Learning Low-Rank Matrices with the Trace Norm

Abstract: We consider the problem of learning a high-dimensional but low-rank matrix from a large-scale dataset distributed over several machines, where low-rankness is enforced by a convex trace norm constraint. We propose DFW-Trace, a distributed Frank-Wolfe algorithm which leverages the low-rank structure of its updates to achieve efficiency in time, memory and communication usage. The step at the heart of DFW-Trace is solved approximately using a distributed version of the power method. We provide a theoretical analysis of the convergence of DFW-Trace, showing that we can ensure sublinear convergence in expectation to an optimal solution with few power iterations per epoch. We implement DFW-Trace in the Apache Spark distributed programming framework and validate the usefulness of our approach on synthetic and real data, including the ImageNet dataset with high-dimensional features extracted from a deep neural network.

Transistorized ignition system for internal combustion engines

Abstract: 1,077,061. Ignition systems. JOSEPH LUCAS (INDUSTRIES) Ltd. Nov.26, 1963 [Dec. 5, 1962; May 8, 1963; June 27, 1963], Nos. 45985/62; 18140/63 and 25576/63. Heading F1B. Spark ignition apparatus for an internal combustion engine comprises a spark generating circuit for supplying spark-generating pulses to the plugs of the engine in turn a trigger circuit coupled to the spark generating circuit and serving to permit the spark generating circuit to produce a single spark producing pulse each time the trigger circuit is biased by an input, a fixed frequency oscillator providing the biasing input to the trigger circuit and magnetic means driven by the engine for preventing the oscillator from providing the biasing input except when a spark is required. Referring to Figs. 1 to 3, when one of the slots 52 appears between the windings 25, 28 the circuit including the transformer 24 the resistor 29, capacitor 31 and transistor 26 oscillates in known manner to produce an A. C. voltage across the resistor 27. The first effect of this voltage will be to render the transistor 35 conductive. When the transistor 35 conducts current flowing through the resistor 38 can flow through the diode 37 and the collector and emitter of the transistor 35 so that the transistor 42 is cut off. Cutting off the transistor 42 causes a high voltage to be developed in the secondary winding 46 of the ignition transformer and a spark is applied to one of the plugs 48. The transformer 32 causes the current in the transistor 35 to build up by regenerative action until saturation is reached at which point the transistor 35 is switched off and the transistor 42 is switched on again. If the transistor 26 and its associated components are still oscillating a further spark will be produced. Thus at speeds below a predetermined value more than one spark will be applied to each plug. Timing may be controlled by a centrifugal advance mechanism and by a known mechanism which is responsive to the pressure in the air inlet of the engine. If desired the air gap may be of such a size that oscillations are prevented from occurring. In this case, as shown in Fig. 6, the core 49 may be U-shaped and the disc 51 is replaced by a spindle including four magnetic arms 72 which permit oscillations when they pass over the limbs on which the windings 25, 28 are wound. In another modification the windings 25, 28 are wound on the same limb of the core so that they oscillate at all times. However the fixed frequency oscillator is coupled to the remainder of the circuit only when required. Other modifications are described.