A study of high-speed AD and DA converters using redundancy techniques Interim report, May 10, 1963 - May 9, 1964

High speed analog-to-digital converters compared using redundancy encoding technique

A nonlinear encoder Technical report no. 1, 9 May - 9 Sep. 1964

Nonlinear encoder - sinusoidal reference voltage, comparator, nonlinear counter, and clock inhibit circui

Mutual impedance effects in scanned antenna arrays technical report no. 2

Mutual impedance effects in electronically-scanned antenna array

Electronic scanning and beam shaping methods technical report no. 1

Electronically scanned antenna array and beam scannin

The measurement of harmonics produced by a pin diode in a microwave switching application Final report

Measurement of harmonics produced by a pin diode in microwave switc

Failure of classical elasticity in auxetic foams

A recent derivation [P.H. Mott and C.M. Roland, Phys. Rev. B 80, 132104 (2009).] of the bounds on Poisson's ratio, v, for linearly elastic materials showed that the conventional lower limit, -1, is wrong, and that v cannot be less than 0.2 for classical elasticity to be valid. This is a significant result, since it is precisely for materials having small values of v that direct measurements are not feasible, so that v must be calculated from other elastic constants. Herein we measure directly Poisson's ratio for four materials, two for which the more restrictive bounds on v apply, and two having values below this limit of 0.2. We find that while the measured v for the former are equivalent to values calculated from the shear and tensile moduli, for two auxetic materials (v < 0), the equations of classical elasticity give inaccurate values of v. This is experimental corroboration that the correct lower limit on Poisson's ratio is 0.2 in order for classical elasticity to apply.Comment: 9 pages, 2 figure

Location of pattern-disturbing structures in the vicinity of an antenna Final report, Jun. 5, 1963 - Sep. 15, 1966

Location of radiation pattern disturbing structures in vicinity of satellite antenn

A3IR-CORE at Purdue University: An Innovative Partnership Between Faculty, Students, and Industry

Economic realities have begun to motivate public higher education institutions to reexamine their roles in the overall educational process and the associated funding mechanisms that are extant. Such reexamination typically includes both the public/private funding mix and the degree to which a workforce-oriented focus should be employed across curricula. Partnerships between academia and industry are a potential answer to the questions thereby raised, and while such partnerships are nothing new, related structural innovations can improve educational and employment outcomes for students. Industry-sponsored institutional research centers can play a major role in facilitating these partnerships. Once such center, the recently-developed Advanced Aviation Analytics Institute for Research (A³IR-CORE), is focused on addressing operational challenges within the aviation industry by actively involving both graduate and undergraduate student researchers working closely with faculty mentors in a highly-collaborative multidisciplinary environment. This article describes the structure and function of the Institute and provides an early glimpse of the positive student educational and employment outcomes that have thus far been achieved

Measurement of Airport Operations Using a Low-Cost Transponder Data Receiver and Collection Unit

Accurate counts of aircraft operations at unmonitored or partially-monitored general aviation airports are important due to their role in the allocation of funds for airport development and improvement. While the Federal Aviation Administration annually invests approximately $1B in small commercial and general aviation airports, fewer than 270 of these 2,950 airports have either full- or part-time air traffic personnel available to register operations counts. Aircraft operations at airports with limited personnel may be counted using temporary acoustic, pneumatic, or video devices, and observations from contract staff. The related sample sizes are inherently small, leading to inaccuracies in the extrapolation of long-term totals. In some cases, the counts may simply be estimated unscientifically by airport managers. Data from aircraft transponders, critical for the safe and efficient management of airspace, may also be used to accurately count airport operations. This data may be collected by a receiver and analyzed with appropriate algorithms. While a majority of the data records (Basic Mode S and Mode C) do not include aircraft positions, a small portion (Extended Mode S) contain position information from which aircraft distances may be directly computed. This dissertation describes a method by which these known distances may be used to calibrate an adaptive digital filter that can be used to estimate distances for the remainder of the aircraft that do not transmit position information. The resulting distance estimates, which exhibit an average error of 0.77 nm per transponder record within 5.0 nm of the receiver, may then be used in conjunction with aircraft altitude and other parameters to identify and register airport operations. Over 16 million data records from three receiver installations at two general aviation airports with collection periods varying from eight to 180 days were used to evaluate the algorithms. The automated operations counts were compared with official air traffic control tower counts obtained from the FAA’s Air Traffic Activity Data System (ATADS) database. A 180-day evaluation found the algorithm provided counts within 2.2% of 52,750 operations; shorter-term comparisons were accurate to within 10% of the FAA counts. The method therefore appears to be an effective and inexpensive means of establishing accurate operations counts at airports with limited personnel

Fingerprints of intrinsic phase separation: magnetically doped two-dimensional electron gas

In addition to Anderson and Mott localization, intrinsic phase separation has long been advocated as the third fundamental mechanism controlling the doping-driven metal-insulator transitions. In electronic system, where charge neutrality precludes global phase separation, it may lead to various inhomogeneous states and dramaticahttp://arxiv.org/submit/215787/metadata arXiv Submission metadatally affect transport. Here we theoretically predict the precise experimental signatures of such phase-separation-driven metal-insulator transitions. We show that anomalous transport is expected in an intermediate regime around the transition, displaying very strong temperature and magnetic field dependence, but very weak density dependence. Our predictions find striking agreement with recent experiments on Mn-doped CdTe quantum wells, a system where we identify the microscopic origin for intrinsic phase separation.Comment: 4+epsilon pages, 4 figure