U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: Bradley Alpert (Fed)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 26 - 45 of 45

Predicted Energy Resolution of a Running-Sum Algorithm for Microcalorimeters

December 1, 2011
Author(s)
Bradley K. Alpert, William B. Doriese, Joseph W. Fowler, Joel N. Ullom
The energy resolution of a high-pulse-rate filtering algorithm recently introduced by Hui Tan et al., based on running sums of TES microcalorimeter output streams, is predicted from average pulse shape and noise autocovariance. We compare with empirical

Representation of Acoustic Waves in Unbounded Domains

January 1, 2005
Author(s)
Bradley K. Alpert, Y Chen
Compact, time-harmonic, acoustic sources produce waves that decay too slowly to be square-integrable on a line away from the sources. We introduce an inner product, arising directly from Green s second theorem, to form a Hilbert space of these waves and

Causal Characteristic Impedance of Planar Transmission Lines

May 1, 2003
Author(s)
Dylan F. Williams, Bradley K. Alpert, Uwe Arz, Hartmut Grabinski
Abstract: We compute power-voltage, power-current, and causal definitions of the characteristic impedance of microstrip and coplanar-waveguide transmission lines on insulating and conducting silicon substrates, and compare to measurement.

Spherical Near-Field Antenna Measurements Using Nonideal Measurement Locations

November 8, 2002
Author(s)
Ronald C. Wittmann, Bradley Alpert, Michael H. Francis
We introduce a near-field spherical scanning algorithm that relaxes the usual condition requiring data points to be on a regular spherical grid. Computational complexity is of the same order as for the standard (ideal-positioning) spherical-scanning

A Representation of Acoustic Waves in Unbounded Domains

October 1, 2002
Author(s)
Bradley K. Alpert, Yu-Hsuan Chen
Compact, time-harmonic, acoustic sources produce waves that decay too slowly to be square-integrable on a line away from the sources. We introduce an inner product, arising directly from Green's second theorem, to form a Hilbert space of these waves, and

Nonreflecting Boundary Conditions for the Time-Dependent Wave Equation

July 1, 2002
Author(s)
Bradley K. Alpert, L Greengard, T Hagstrom
We describe a new, efficient approach to the imposition of exact nonreflecting boundary conditions for the scalar wave equation. We compare the performance of our approach with that of existing methods by coupling the boundary conditions to finite

Causality and Waveguide Circuit Theory

April 1, 2001
Author(s)
Darren F. Williams, Bradley Alpert
We develop a new causal power-normalized wave-guide equivalent-circuit theory that, unlike its predecessors, results in network parameters usable in both the frequency and time domains in a broad class of waveguides. Enforcing simultaneity of the voltages

Causality and Characteristic Impedance

December 2, 1999
Author(s)
Dylan F. Williams, Bradley K. Alpert
A new causal power-normalized waveguide equivalent-circuit theory fixes both the magnitude and phase of the characteristic impedance of a waveguide.

Characteristic Impedance of Microstrip on Silicon

October 25, 1999
Author(s)
Dylan F. Williams, Bradley K. Alpert
We compare power-voltage, power-current, and causal definitions of the characteristic impedance of microstrip transmission lines on silicon substrates.

Characteristic impedance of microstrip on silicon

October 25, 1999
Author(s)
Dylan F. Williams, Bradley K. Alpert
In this paper, we compare the power-voltage, power-current, and causal definitions of the characteristic impedance of microstrip transmission lines on silicon substrates.

A Causal Microwave Circuit Theory and Its Implications

August 1, 1999
Author(s)
Dylan Williams, Bradley Alpert
We will describe a new causal power-normalized waveguide equivalent-circuit theory and explore its implications. The new theory marries a power normalization with additional constraints that enforce simultancity of the theory's voltages and currents and

Characteristic Impedance, Power, and Causality

May 1, 1999
Author(s)
Dylan F. Williams, Bradley K. Alpert
A new causal power-normalized waveguide equivalent-circuit theory determines uniquely both the magnitude and phase of the characteristic impedance of a waveguide.