Jack Gelfand

Theory and development of higher-order CMAC neural networks

The cerebellar model articulation controller (CMAC) neural network is capable of learning nonlinear functions extremely quickly due to the local nature of its weight updating. The rectangular shape of CMAC receptive field functions, however, produces discontinuous (staircase) function approximations without inherent analytical derivatives. The ability to learn both functions and function derivatives is important for the development of many online adaptive filter, estimation, and control algorithms. It is shown that use of B-spline receptive field functions in conjunction with more general CMAC weight addressing schemes allows higher-order CMAC neural networks to be developed that can learn both functions and function derivatives. This also allows hierarchical and multilayer CMAC network architectures to be constructed that can be trained using standard error back-propagation learning techniques.<<ETX>>

Integrating neural networks and knowledge-based systems for intelligent robotic control

A methodology is presented for integrating artificial neural networks and knowledge-based systems for the purpose of robotic control. The integration is patterned after models of human motor skill acquisition. The initial control task chosen to demonstrate the integration technique involves teaching a two-link manipulator how to make a specific type of swing. A three-level task hierarchy is defined consisting of low-level reflexes, reflex modulators, and an execution monitor. The rule-based execution monitor first determines how to make a successful swing using rules alone. It then teaches cerebellar model articulation controller (CMAC) neural networks how to accomplish the task by having them observe rule-based task execution. Following initial training, the execution monitor continuously evaluates neural network performance and re-engages swing-maneuver rules whenever changes in the manipulator or its operating environment necessitate retraining of the networks. Simulation results show the interaction between rule-based and network-based system components during various phases of training and supervision.<<ETX>>

Photoacoustic detection spectroscopy with dye laser excitation. The 6190 Å CH4 and the 6450 Å NH3 bands

Abstract We have applied photoacoustic detection to the observation of the weak visible overtone transitions of CH 4 and NH 3 . Spectra were obtained by placing the photoacoustic cell in the cavity of a dye laser and scanning the laser across the absorption band. A spectral resolving power of over 200 000 proved to be adequate to resolve single rotational features (probably rotational manifolds) within these complex bands. The application of these results to the observational study of the major planetary atmosphere is indicated.

Implementing Real-Time Optimization Models: A Case Application From The Motor Carrier Industry

Online models for real-time operations planning face a host of implementation issues that do not arise in more strategic arenas. We use the seemingly simple problem of assigning drivers to loads in the truckload motor carrier industry as an instance to study the issues that arise in the process of implementing a real-time dispatch system. Although the project was moderately successful, our focus is not on documenting the benefits, but rather on summarizing the challenges that arose. The most significant theme running through the implementation hurdles we encountered was the lack of information available to the model. Computers are very good at processing vast quantities of information; humans are very good at challenging the information that is in the computer and augmenting computer-provided data with head knowledge. Our study includes a careful comparison of actual decisions with model recommendations, using a six-month database of actual transactions. This comparison is the first we have seen of its kind and provides the most rigorous evaluation of an online dispatch model that we have seen. Although the model was well used, the results demonstrate that significant improvements could have been obtained if the level of model utilization had been even higher.

Bimodal optical computers.

Analog optical solutions of numerical problems tend to be fast, simple, and inaccurate. Digital optical or electronic solutions to the same problems tend to be slower, harder, and more accurate. In circumstances outlined here, hybrid analog-digital systems can be built which give the accuracy of digital solutions with intermediate degrees of speed and simplicity. Because at any instant these processors are working in either the analog or the digital mode, we call them bimodal optical computers.

Direct inversion of high overtone collision broadened linewidths in the HCl–HCl system: Rotationally inelastic rates for highly vibrationally excited molecules

In this paper we present preliminary results for rotation–rotation inelastic collision rates for HCl molecules in vibrationally excited states up to v = 6 colliding with ground state HCl molecules. These were obtained by inverting the measured collision broadened linewidths of overtone vibration–rotation transitions up to the 6–0 overtone band. An energy corrected sudden scaling theory was used to reduce the number of independent parameters sufficiently so that the rates could be determined directly from the available experimental linewidths.

A time domain photoacoustic study of the collisional relaxation of vibrationally excited H2

Abstract We report the first direct measurement of the vibration-to-vibration (V-V) and vibration-to-translation (V-T) rates for vibrational relaxation out of the ν=2 vibrational level in hydrogen gas. Time domain photoacoustic spectroscopy was used to monitor the collision dynamics after excitation into ν=2 through overtone stimulated Raman pumping. The V-V relaxation rate is found to be (1–4) × 10−14 cm3 s−1 molecule−1 and the V-T rate constant is (0.6–2) × 10−15 cm3 s−1 molecule−1 for normal hydrogen at 298 K.

Helium and self-broadening in the first and second overtone bands of 12C16O

Abstract The pressure broadening coefficients for rotation-vibration lines of J states up to 22 in the 2-0 band and J states up to 20 in the 3-0 band of pure CO and HeCO mixtures were measured. The data were obtained at room temperature utilizing a Fourier transform spectrometer and various cells, including a 113-m White cell. These data exhibit little change with increasing vibrational level, and in the case of helium broadening, only slight J dependence.

Collision dynamical information from pressure broadening measurements: Application to carbon monoxide

Self‐ and helium‐broadened carbon monoxide linewidths have been inverted to obtain state‐to‐state rate constants using the energy corrected sudden scaling formalism. Selected rotation–rotation and rotation‐translation rate constants are discussed as a function of vibrational and rotational levels for the CO–CO and He–CO systems. We find that there is no dependence of the collision dynamics upon the vibrational state of the collision partners up to v=3. In addition, relaxation in both these systems is found to be dominated by rotation‐translation collisions. However they are qualitatively different in their dynamical characteristics and result in signficantly varied state‐to‐state rate constants. An analysis of the effect of collision partners in the CO–X (X=CO, He, Ne, Ar, Xe, H2) system is presented. Comparisons are made with the available data in the literature.

Absorption intensities for the 4-0 through 7-0 overtone bands of HCl

Abstract We have measured the absorption intesities for a number of rotation-vibration lines in the 4-0 through 7-0 overtone bands of HCl utilizing a Fourier transform spectrometer and a 409.6 m path length White cell. Individual line strengths, band strengths, dipole matrix elements, and Herman-Wallis factors are presented.