NEC

About: NEC is a company organization based out in Tokyo, Japan. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 33269 authors who have published 57670 publications receiving 835952 citations. The organization is also known as: NEC Corporation & NEC Electronics Corporation.

The MPEG-7 color layout descriptor: a compact image feature description for high-speed image/video segment retrieval

Abstract: This paper proposes a color feature description for image and video retrieving applications such as personal video recorder, which manages a large amount of data. This descriptor specifies the spatial distribution of colors with a few nonlinear quantized DCT coefficients of grid based average colors. The tradeoff between the number of the coefficients enclosed in the descriptor and retrieval cost is studied. The experimental results show that the descriptor enclosing six for luminance and three for each chrominance coefficient achieves the best trade-off between the storage cost and retrieval efficiency. It requires 6 bits for DC and 5 bits for AC coefficients, and therefore total storage cost is just 63 bits per image. This description, named color layout descriptor, has been accepted as a part of the MPEG-7 final committee draft.

Receipt-free mix-type voting scheme - A practical solution to the implementation of a voting booth-

Abstract: We present a receipt-free voting scheme based on a mixtype anonymous channel[Cha81, PIK93]. The receipt-freeness property [BT94] enables voters to hide how they have voted even from a powerful adversary who is trying to coerce him. The work of [BT94] gave the first solution using a voting booth, which is a hardware assumption not unlike that in current physical elections. In our proposed scheme, we reduce the physical assumptions required to obtain receipt-freeness. Our sole physical assumption is the existence of a private channel through which the center can send the voter a message without fear of eavesdropping.

Growth of carbon nanotubes

Abstract: The production, morphologies and atomic structures of carbon nanotubes are reviewed, and a mechanism for tube growth is discussed on the basis of transmission electron microscopy observations. Capping of carbon nanotubes is explained nicely in terms of pentagons; distributions of pentagons in a hexagon network cause various cap morphologies. Heptagons, resulting in negative curvature into a graphitic plane, also provide a variety of graphitic structures. Pentagons and heptagons seem to play a key role in tube growth. On the basis of the consistency of various tube morphologies, we propose a model for tubule growth, in which the tubules are open at their ends while growing in the carbon arc plasma. To support this open-end growth mechanism, other evidence such as layer-by-layer growth on the tube surfacces and “over-shooting growth” on tube tips is given.

Current-dependent light-emitting element drive circuit for use in active matrix display device

Abstract: In a light-emitting element drive circuit in an active matrix display device, at least one current-control transistor controls a current flowing through a light-emitting element. The current-control transistor and the light-emitting element are connected in parallel to each other. A constant current source is connected to a junction between one electrode of the light-emitting element and one electrode of the transistor through which the current 8s controlled to flow. The other electrodes of the light-emitting element and the transistor are connected to a common electrode which may be grounded via a resistor. In other configuration, it may be arranged that the light-emitting element and a capacitance are connected in parallel to each other. In this case, the current-control transistor is connected to a function between the light-emitting element and the capacitance so as to use charging and discharging operations of the capacitance for driving the light-emitting element.

Superconductivity in sodium-and lithium-containing alkali-metal fullerides

Abstract: THE discovery1 of superconductivity, with a transition temperature Tc of 18 K, in potassium-doped C60 was followed by the synthesis of other superconducting M3C60 phases: Rb3C60 (Tc = 28K and 30 K; refs 2, 3), CsRb2C60 (Tc = 31K; ref. 4) and Cs2RbC60 (Tc = 33 K; ref. 4). A monotonic relationship is observed5 between Tc and lattice constant a0 for these face-centred cubic M3C0 compounds, all of which have a0 values larger than that of pure C60. Here we study this relationship over a wider range using mixed alkali compounds incorporating sodium (Na2MC60, where M is K, Rb or Cs) and lithium (Li2CsC60). The Na2MC60 compounds have face-centred cubic structures and are superconducting, with Tc = 12 K (M = Cs), 2.5 K (M = Rb) and 2.5 K (M = K); these Tcs are lower than those predicted on the basis of high-pressure studies6–8. This departure from the previous relationship between Tc and a0 for lattice parameters smaller than that of pristine C60 may provide new insights into what controls superconductivity in these materials.