2,364 research outputs found
Reduced 30% scanning time 3D multiplexer integrated circuit applied to large array format 20KHZ frequency inkjet print heads
Enhancement of the number and array density of nozzles within an inkjet head
chip is one of the keys to raise the printing speed and printing resolutions.
However, traditional 2D architecture of driving circuits can not meet the
requirement for high scanning speed and low data accessing points when nozzle
numbers greater than 1000. This paper proposes a novel architecture of
high-selection-speed three-dimensional data registration for inkjet
applications. With the configuration of three-dimensional data registration,
the number of data accessing points as well as the scanning lines can be
greatly reduced for large array inkjet printheads with nozzles numbering more
than 1000. This IC (Integrated Circuit) architecture involves three-dimensional
multiplexing with the provision of a gating transistor for each ink firing
resistor, where ink firing resistors are triggered only by the selection of
their associated gating transistors. Three signals: selection (S), address (A),
and power supply (P), are employed together to activate a nozzle for droplet
ejection. The smart printhead controller has been designed by a 0.35 um CMOS
process with a total circuit area, 2500 x 500 microm2, which is 80% of the
cirucuit area by 2D configuration for 1000 nozzles. Experiment results
demonstrate the functionality of the fabricated IC in operation, signal
transmission and a potential to control more than 1000 nozzles with only 31
data access points and reduced 30% scanning time.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Three dimensional viscous analysis of a hypersonic inlet
The flow fields in supersonic/hypersonic inlets are currently being studied at NASA Lewis Research Center using 2- and 3-D full Navier-Stokes and Parabolized Navier-Stokes solvers. These tools have been used to analyze the flow through the McDonnell Douglas Option 2 inlet which has been tested at Calspan in support of the National Aerospace Plane Program. Comparisons between the computational and experimental results are presented. These comparisons lead to better overall understanding of the complex flows present in this class of inlets. The aspects of the flow field emphasized in this work are the 3-D effects, the transition from laminar to turbulent flow, and the strong nonuniformities generated within the inlet
Modeling The Cutoff Frequency Of Single-Heterojunction Bipolar-Transistors Subjected To High Collector-Layer Current
High current densities in the collector layer reduce the cutoff frequency of heterojunction bipolar transistors. We develop a model based on analytical expressions that describe this reduction. These expressions represent the contributions from each of six regions defined in the output currentāvoltage characteristic. The model has parameters determined entirely by device physical makeup. It has no fitting parameters. Its predictions agree well with experimental data taken on two N/p+/n aluminumāgalliumāarsenide/galliumāarsenide transistors having abrupt junctions grown by molecularābeam epitaxy. Because previous models omitted the effects of high current densities, their predictions agree less favorably. The development of the model considers the effects that compoundāsemiconductor properties such as velocity overshoot have on the cutoff frequency
Anatomy of the Soft-Photon Approximation in Hadron-Hadron Bremsstrahlung
A modified Low procedure for constructing soft-photon amplitudes has been
used to derive two general soft-photon amplitudes, a two-s-two-t special
amplitude and a two-u-two-t special amplitude
, where s, t and u are the Mandelstam variables.
depends only on the elastic T-matrix evaluated at four sets
of (s,t) fixed by the requirement that the amplitude be free of derivatives
(T/s and /or T/). Likewise
depends only on the elastic T-matrix evaluated at four sets
of (u,t). In deriving these amplitudes, we impose the condition that
and reduce to and
, respectively, their tree level approximations. The
amplitude represents photon emission from a sum of
one-particle t-channel exchange diagrams and one-particle s-channel exchange
diagrams, while the amplitude represents photon
emission from a sum of one-particle t-channel exchange diagrams and
one-particle u-channel exchange diagrams. The precise expressions for
and are determined by using the
radiation decomposition identities of Brodsky and Brown. We point out that it
is theoretically impossible to describe all bremsstrahlung processes by using
only a single class of soft-photon amplitudes. At least two different classes
are required: the amplitudes which depend on s and t or the amplitudes which
depend on u and t. When resonance effects are important, the amplitude
, not , should be used. For processes with
strong u-channel exchange effects, the amplitude should be
the first choice.Comment: 49 pages report # LA-UR-92-270
DRAGONS - A Micrometeoroid and Orbital Debris Impact Sensor
The Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is intended to be a large area impact sensor for in situ measurements of micrometeoroids and orbital debris (MMOD) in the millimeter or smaller size regime. These MMOD particles are too small to be detected by ground-based radars and optical telescopes, but are still large enough to be a serious safety concern for human space activities and robotic missions in the low Earth orbit (LEO) region. The nominal detection area of a DRAGONS unit is 1 m2, consisting of several independently operated panels. The approach of the DRAGONS design is to combine different particle impact detection principles to maximize information that can be extracted from detected events. After more than 10 years of concept and technology development, a 1 m2 DRAGONS system has been selected for deployment on the International Space Station (ISS) in August 2016. The project team achieved a major milestone when the Preliminary Design Review (PDR) was completed in May 2015. Once deployed on the ISS, this multi-year mission will provide a unique opportunity to demonstrate the MMOD detection capability of the DRAGONS technologies and to collect data to better define the small MMOD environment at the ISS altitude
In Situ Measurement Activities at the NASA Orbital Debris Program Office
The NASA Orbital Debris Program Office has been involved in the development of several particle impact instruments since 2003. The main objective of this development is to eventually conduct in situ measurements to better characterize the small (millimeter or smaller) orbital debris and micrometeoroid populations in the near-Earth environment. In addition, the Office also supports similar instrument development to define the micrometeoroid and lunar secondary ejecta environment for future lunar exploration activities. The instruments include impact acoustic sensors, resistive grid sensors, fiber optic displacement sensors, and impact ionization sensors. They rely on different mechanisms and detection principles to identify particle impacts. A system consisting of these different sensors will provide data that are complimentary to each other, and will provide a better description of the physical and dynamical properties (e.g., size, mass, and impact speed) of the particles in the environment. Details of several systems being considered by the Office and their intended mission objectives are summarized in this paper
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