-
[show abstract]
[hide abstract]
ABSTRACT: The Hurricane Imaging Radiometer System (HIRAD) is a new airborne passive microwave remote sensor developed to observe hurricanes. HIRAD incorporates synthetic thinned array radiometry technology, which use Fourier synthesis to reconstruct images from an array of correlated antenna elements. The HIRAD system response to a point emitter has been measured in an anechoic chamber. With this data, a Fourier inversion image reconstruction algorithm has been developed. Performance analysis of the apparatus is presented, along with an overview of the image reconstruction algorithm.
Geoscience and Remote Sensing Symposium (IGARSS), 2010 IEEE International; 08/2010
-
[show abstract]
[hide abstract]
ABSTRACT: This paper describes the end-to-end simulation of the new HIRAD, which will provide improved hurricane surveillance. This paper (part-2 of 2) evaluates the HIRAD instrument performance in retrieving hurricane-force wind speeds in the presence of intense rain. Examples of retrieved hurricane wind speed and rain rate images are presented, and comparisons of the retrieved parameters with the MM5 numerical hurricane model data are made. Statistical results are presented over a broad range of wind and rain conditions over the full measurement swath.
Microwave Radiometry and Remote Sensing of the Environment (MicroRad), 2010 11th Specialist Meeting on; 04/2010
-
[show abstract]
[hide abstract]
ABSTRACT: It is shown that the electromagnetic theory of the superconducting AC machine is very close to that of the surface-magnet permanent-magnet synchronous machine. Methods for calculating the EMF and synchronous inductances are practically identical and almost interchangeable. It is not only possible to use related algorithms for design calculations, but the results are readily compared in a form convenient for studies, especially of very large machines. The theory includes not only the steady state but also the subtransient state following a short-circuit fault. Methods for analyzing the demagnetization of permanent magnets, or the quenching of the superconducting winding, are closely related. The paper describes all the main points of the theory with numerical and graphical illustrations.
Electrical Machines and Systems, 2009. ICEMS 2009. International Conference on; 12/2009
-
[show abstract]
[hide abstract]
ABSTRACT: We present an online system for recognizing handwritten mathematical matrices in the context of an interactive computational tool called MathPaper. Automatic segmentation and recognition of multiple expressions are supported based on a spacing algorithm that leverages recognized symbol identities, sizes, and relative locations of individual symbols. Matrices with ellipses can be recognized and instantiated with non-ellipsis elements. Both well- and non-well-formed matrices can also be recognized. Matrix elements can be any general mathematical expressions including imbedded matrices. Our recognizer also addresses the poor column alignment problem of handwritten matrices, and allows for slight horizontal overlaps between elements in neighboring columns and different rows.
Pattern Recognition, 2008. ICPR 2008. 19th International Conference on; 01/2009
-
[show abstract]
[hide abstract]
ABSTRACT: As part of the rapidly evolving field of designing more natural user interfaces for multimedia information, pen-centric computing refuses to disappear. As a quite natural and universal interface modality, it presents many challenges. In this article, the pen-centric computing group at Brown University, led by Andries Van Dam, surveys the many prototypes they have designed and implemented, and discuss the research issues in the field still to be explored.
IEEE Multimedia 01/2009; · 0.44 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper aims to define a minimum set of finite element solutions to be used in the design and analysis of saturated permanent-magnet motors. The choice of the finite element solutions belonging to this set is strictly associated with the classical d - q axis theory and it is described in terms of key points on the Flux-MMF diagram. When synchronous machine are considered, such a diagram has a regular shape, so that a huge reduction in finite element field solutions is possible with no loss of accuracy. It is also shown that the torque computed by using the d - q axis theory is almost independent of variation of the flux linkage with the rotor position. At last, the paper describes a technique in which few finite element solutions allow the identification not only of the average torque, but also the main torque harmonics. As a results, the torque behavior versus rotor position can be rapidly predicted.
Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE; 10/2007
-
[show abstract]
[hide abstract]
ABSTRACT: Single-phase and two-phase induction machines are widely used in commercial applications due to their low cost and high reliability. The developed methods for the analysis of the single-phase induction motor, i.e. forward-backward field, symmetrical components and cross-field methods, can be adapted for modeling the MMF harmonics effect. This paper presents a unified approach on all these methods that demonstrates the equivalence between models and shows how the equivalent circuit elements can be interchanged from one method to another. Since half-cycle symmetry is a very common condition in the mass produced single-phase induction motors, this paper analyses only the odd MMF harmonic effects. Experimental results for three capacitor-run motors are used to validate all the proposed models.
Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE; 10/2007
-
[show abstract]
[hide abstract]
ABSTRACT: A procedure is described for identifying a general mathematical model of core losses in ferromagnetic steel based on a minimal amount of experimental data. This model has a hysteresis loss multiplicative coefficient variable with frequency and induction and a combined coefficient for eddy-current and excess losses that is also variable with frequency and induction. A physical interpretation and a test procedure for the identification of the core loss coefficients are proposed. Validation was successfully performed on a number of different samples of non-grain oriented fully and semi-processed steel alloys.
Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE; 10/2007
-
[show abstract]
[hide abstract]
ABSTRACT: Interior permanent magnet motors equipped with a squirrel-cage rotor are receiving lately an increased interest. Defined as line-start, line-fed or hybrid synchronous-induction motors, such machines combine the advantage of the brushless permanent magnet motors, i.e. high efficiency, constant torque for variable speed, with the high starting capability of the induction motors connected directly to the supply system. This paper proposes a unified analysis of these motors, with an emphasis on how any possible configuration may be described by using symmetrical components and two equivalent fictitious machines: positive and negative sequences. The analysis is validated on a single-phase unbalanced and on a three-phase balanced line-fed interior permanent magnet motors.
Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE; 10/2007
-
D. Cheng,
D. Hunt,
H. Hsieh,
J. Meneghetti,
K. Kennedy,
T. Stevens,
G. Jones, T. Miller,
D. Colomb,
L. Bertolini,
C. Belser,
J. Kerns,
E. Daly
[show abstract]
[hide abstract]
ABSTRACT: The PEP-II B Factory Low-Energy Ring (LER) will operate at 3.1 GeV
with 2.1 A; design specifications are based on 3.5 GeV at 3 A. The
vacuum system, 2200 m long, consists of 6 arcs and 6 straights. The arc
vacuum system is based on an aluminum antechamber pumped by titanium
sublimators located directly under discrete photon stops, supplemented
by 110 1/s ion pumps near the end of each dipole. The straight sections
serve various utility functions, including emittance control with a
wiggler, injection, and an interaction region (IR). Vacuum chambers in
most of the straight sections are circular stainless steel pipe with
external copper plating to facilitate heat transfer to cooling tubes
brazed to the outside wall. The wiggler chicane vacuum system uses both
aluminum and stainless steel technology, along with a 24 m long
distributed copper photon dump. The IR vacuum system is mainly based on
copper extrusions. LER vacuum system components are either in the late
stage of prototyping or already in full production
Particle Accelerator Conference, 1997. Proceedings of the 1997; 06/1997
-
[show abstract]
[hide abstract]
ABSTRACT: We have measured the deep level transient spectroscopy signal height of two DX levels usually observed in n‐type doped Al 0.32 Ga 0.68 As as a function of the filling pulse width. We report an overshoot in the capture transient of the DX level having a larger capture rate. We solve the rate equations for the capture processes of these two DX levels simultaneously. The capture transients thus obtained fit the experimental capture transients of these two DX levels reasonably well.
Applied Physics Letters 08/1991; · 3.84 Impact Factor
