Gabriel Laufer

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Papers by Gabriel Laufer

Teaching engineering in the middle schools: Virginia Middle Schools Engineering Education Initiative

32nd Annual Frontiers in Education

Implications of Atmospheric Temperature Fluctuations on Passive Remote Sensing of Chemicals

Passive remote sensing of airborne chemicals at infrared wavelengths may be limited by temporal f... more Passive remote sensing of airborne chemicals at infrared wavelengths may be limited by temporal fluctuations in atmospheric brightness temperatures delta T(Delta t). The fluctuations delta T increase the minimum detectable chemical vapor concentration-pathlength product (CL) given by the noise-equivalent-CL (NECL) of the measurements scenario. Brightness temperatures in two infrared spectral bands were measured on clear and cloudy days along three lines of sights. For time windows Delta t < 3-5 s, delta T(Delta t) remained constant at the sensor noise-level and rapidly increased as Delta t increased. The fluctuation time scale for the cloudy day was longer than those for the clear day and the magnitude of the fluctuations was smaller. At the conditions of clear day tests, passive remote sensing of airborne chemicals would have reached its maximum sensitivity with an integration interval Delta t = 3-5 s with sensitivity diminishing fast with longer detection time-windows.

Low Cost Passive Remote Sensor of Chemicals for Expendable UAVs

Optical Solutions for Homeland and National Security, 2005

ABSTRACT An inexpensive passive remote sensor of weapon and toxic industrial chemicals is develop... more

Flow of Dilute Polymer Solutions through a Packed Bed

Industrial & Engineering Chemistry Fundamentals, 1976

verter and circuit time constants, a total transmission rate of 10 words/sec will be approached, ... more verter and circuit time constants, a total transmission rate of 10 words/sec will be approached, limited of course by the 100-msec tirne constant of monostable 1. use of a faster cycling A D converter, and the appropriate time constant for monostable 1, will allow transmission rates of over 1000 charactedsec. No other changes in the external Circuitry need be made.

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A low-cost chemical sensor for fixed security applications

Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense V, 2006

A low-cost infrared sensor that uses room temperature pyroelectric detectors integrated with band... more A low-cost infrared sensor that uses room temperature pyroelectric detectors integrated with bandpass filters to provide low-resolution spectral scans of the absorption characteristics of hazardous chemicals was developed for fixed security applications. The sensor provides fast (1 s) and continuous monitoring, detection, and identification capabilities. A unique detection and identification algorithm that uses non-linear computation techniques to account for the

University of Virginia suborbital infrared sensing experiment

SPIE Proceedings, 2002

An Orion sounding rocket launched from Wallops Flight Facility carried a University of Virginia p... more An Orion sounding rocket launched from Wallops Flight Facility carried a University of Virginia payload to an altitude of 47 km and returned infrared measurements of the Earth&amp;amp;amp;amp;#39;s upper atmosphere and video images of the ocean. The payload launch was the result of a three-year undergraduate design project by a multi-disciplinary student group from the University of Virginia and James

Multiphoton ionization of N_2 by the third harmonic of a Nd:YAG laser: a new avenue for air diagnostics

Optics Letters, 1991

Ionization of N(2) by the third harmonic of a Nd:YAG laser is demonstrated and confirmed experime... more Ionization of N(2) by the third harmonic of a Nd:YAG laser is demonstrated and confirmed experimentally from both spectral and ion-collection measurements. Six photons at 355 nm excite the ground-state neutral molecule to the B(2) summation operator(+)(u) (upsilon&#39; = 8) ionized state. Intense radiation at 391.4 nm associated with the B(2) summation operator(+)(u) (upsilon = 0) ? X(2) summation operator(+)(g) (upsilon&#39;&#39; = 0) transition was detected. The intensity of this line scales quadratically with the laser power. An ion concentration of 3.25 x 10(13) ions/cm(3) was detected after irradiation by a 45-mJ laser pulse focused to a diameter of 17 microm. The potential application of this ionization scheme for air velocity and temperature measurements is presented.

Measurements of atmospheric brightness temperature fluctuations and their implications on passive remote sensing

Optics Express, 2005

Electrostatic mechanisms of aerosol collection by granular filters: A review

Journal of Aerosol Science, 1988

ABSTRACT

Water assisted multi-photon ionization of N2 by KrF lasers

Chemical Physics Letters, 1997

Abstract Effects of water vapor on multiphoton ionization of N2 by a narrowband tunable KrF laser... more Abstract Effects of water vapor on multiphoton ionization of N2 by a narrowband tunable KrF laser were compared to ionization of dry N2. In dry N2, ionization is non-resonant and requires 3 + 1 photon absorptions. In the presence of water, ionization is through a resonant two-photon excitation of H2O, followed by collisional energy exchange with N2 molecules and two single-photon absorption steps. Excited N2+ ions were detected by emission in the B2Σu+(υ′ = 0) → X2Σg+(υ″ = 0) band. Owing to the resonant enhancement of H2O excitation, this emission is bright and may be used to visualize N2H2O mixing flows.

Picosecond double pass amplifier

Applied Optics, 1980

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Experimental Study on Electrostatically Enhanced Granular Filters

Aerosol Science and Technology, 1986

Electrostatically Enhanced Granular Bed Filters

Aerosol Science and Technology, 1986

Teaching engineering in the middle schools: Virginia Middle Schools Engineering Education Initiative

by Gabriel Laufer and Larry Richards

The Virginia Middle Schools Engineering Education Initiative (VMSEEI) will design, implement, tes... more The Virginia Middle Schools Engineering Education Initiative (VMSEEI) will design, implement, test and evaluate "engineering leaching kits" to be used by teachers and student teachers to facilitate engineering instruction in the middle schools. The engineering teaching kits (ETKs) will allow teachers to instruct students on selected engineering concepts and procedures within the context of preexisting science and mathematics classes. ETKs will include a strong focus on design and innovation, how things work, how things are made, and the social and environmental impacts of technology. Each ETK will include a student guide explaining key concepts and methods, a teacher's guide, plans for demonstrations and experiments, and where appropriate a computer-based component (such as a demonstration or simulation). The ETKs will involve active, hands-on, cooperative learning; students will work in teams to solve problems and design solutions.

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Teaching engineering in the middle schools: Virginia Middle Schools Engineering Education Initiative

32nd Annual Frontiers in Education