The Diffusion of Cattle Ranching and Deforestation – Prospects for a Hollow Frontier in Mexico’s Yucatán

This article investigates the behavioral drivers of pasture creation and associated implications for deforestation in a 22,000 km2 agricultural frontier spanning the base of Mexico‘s southern Yucatán. After developing a theoretical model that highlights the role of social networks and information spillovers with respect to the decision to begin cattle ranching, we use household data to estimate an econometric duration model of the determinants of pasture creation. Although pasture fi ts well with the typical household‘s resource constraints, its continued expansion contributes to a hollow frontier dynamic in which the spread of low-value cattle ranching coincides with decreasing population.Pasture creation; information spillovers; duration analysis; farm households; Mexico

Neural network control of nonstrict feedback and nonaffine nonlinear discrete-time systems with application to engine control

In this dissertation, neural networks (NN) approximate unknown nonlinear functions in the system equations, unknown control inputs, and cost functions for two different classes of nonlinear discrete-time systems. Employing NN in closed-loop feedback systems requires that weight update algorithms be stable...Controllers are developed and applied to a nonlinear, discrete-time system of equations for a spark ignition engine model to reduce the cyclic dispersion of heat release --Abstract, page iv

Color.

Color, any attempt to apply the scientific principles of color vision in the making of a picture must surely fail if it be not granted at the out set that it is only to a limited degree that those principles can apply. Color appreciation is as much a psychical as a physiological, and indeed, it is psychical not only with regard to the objective impression itself, but also with regard to the subjective, the associational mental process. Previous knowledge and training, experience traditions, the association of color impressions with impressions previously received through other senses and stored away as memories, all play a part in determining the effect which a color or a pattern of opposed colors has upon us. But even granting all this, there are many of the physical and physiological laws of color vision which must be adhered to before we can expect to produce these effects

Experimental verification and practical application of torquewhirl theory of rotordynamic instability

A theory developed by Vance in 1978 to explain the destabilizing effect of torque on a whirling rotor was experimentally verified. The measurements made on a specially designed test apparatus are described. New computer models were also developed to investigate the effect of torque on rotordynamic stability of multidisk flexible rotor bearing systems. The effect of torque was found to be most pronounced when the system is already marginally stable from other influences. The modifications required to include torque in a typical shaft transfer matrix are described, and results are shown which identify the type of rotor design most sensitive to load torque

A Comparison of Interpolation Methods for Sparse Data: Application to Wind and Concentration Fields

In order to produce gridded fields of pollutant concentration data and surface wind data for use in an air quality model, a number of techniques for interpolating sparse data values are compared. The techniques are compared using three data sets. One is an idealized concentration distribution to which the exact solution is known, the second is a potential flow field, while the third consists of surface ozone concentrations measured in the Los Angeles Basin on a particular day. The results of the study indicate that fitting a second-degree polynomial to each subregion (triangle) in the plane with each data point weighted according to its distance from the subregion provides a good compromise between accuracy and computational cost

The diffusion of cattle ranching and deforestation

This article investigates the behavioral drivers of pasture creation and associated implications for deforestation in a 22,000 km2 agricultural frontier spanning the base of Mexico’s southern Yucatán. After developing a theoretical model that highlights the role of social networks and information spillovers with respect to the decision to begin cattle ranching, we use household data to estimate an econometric duration model of the determinants of pasture creation. Although pasture fits well with the typical household’s resource constraints, its continued expansion contributes to a hollow frontier dynamic in which the spread of low-value cattle ranching coincides with decreasing population

Control of Nonaffine Nonlinear Discrete Time Systems using Reinforcement-learning-Based Linearly Parameterized Neural Networks

A nonaffine discrete-time system represented by the nonlinear autoregressive moving average with eXogenous input (NARMAX) representation with unknown nonlinear system dynamics is considered. An equivalent affinelike representation in terms of the tracking error dynamics is first obtained from the original nonaffine nonlinear discrete-time system so that reinforcement-learning-based near-optimal neural network (NN) controller can be developed. The control scheme consists of two linearly parameterized NNs. One NN is designated as the critic NN, which approximates a predefined long-term cost function, and an action NN is employed to derive a near-optimal control signal for the system to track a desired trajectory while minimizing the cost function simultaneously. The NN weights are tuned online. by using the standard Lyapunov approach, the stability of the closed-loop system is shown. The net result is a supervised actor-critic NN controller scheme which can be applied to a general nonaffine nonlinear discrete-time system without needing the affinelike representation. Simulation results demonstrate satisfactory performance of the controlle

Effective School Research: Teachers\u27 and Administrators Perceptions of Its Existence on Campus

Effective school research focuses school improvement on the variables that are within the control of educators and have the greatest potential to impact student achievement: 1) instructional leadership, 2) instructional personnel, 3) instructional environment, and 4) instructional programming. In an era of high accountability with many initiatives being proposed for school reform, effective school research continues to provide valuable research-based information to the school principal, superintendent and larger educational community. By examining the school in relation to this research-based information, educational leaders are informed about factors that promote student achievement. This study surveyed teachers and administrators on eight middle school campuses in East Texas public schools serving students in grades 6-8. Surveying teachers and administrators about the perceived presence or absence of effective school research indicators serve as an impetus to engage in dialogue about school improvement as results suggest teachers and administrators who perceived effective school research variables on their campuses were more likely to receive Exemplary or Recognized ratings from the Texas Education Agency