Showing papers by "University of Central Florida published in 1993"

Large nonlinear phase shifts in second-order nonlinear-optical processes.

Abstract: We show that processes such as second-harmonic generation and subsequent downconversion, and parametric mixing in general, can lead to large field-dependent phase shifts for the input beams under a variety of conditions.

The engineering of knowledge-based systems: theory and practice

Abstract: 1. Introduction to Knowledge-Based Systems. 2. Structure. 3. Logic and Automated Reasoning. 4. Forward Reasoning Rule-Based Systems. 5. Backward-Reasoning Systems. 6. Associative Networks, Frames, and Objects. 7. Blackboard Architectures. 8. Uncertainty Management. 9. Advanced Reasoning Techniques. 10. The Software Lifecycle in Knowledge-based Systems. 11. Feasibility Analysis. 12. Requirements Specification and Design. 13. Knowledge Acquisition and System Implementation. 14. Practical Considerations in Knowledge Acquisition. 15. Alternative Knowledge Acquisition Means. 16. Verification and Validation. 17. Legal Issues in Knowledge-Based Systems. Appendix A: The CLIPS System. Appendix B: The Personal Consultant Shell System.

An Analysis of Team Evolution and Maturation

Abstract: Although there has been little research emphasis on the temporal aspects of team development, conventional wisdom has suggested that teams develop in a linear fashion through a sequence of phases. More recent investigations of work groups indicate, however, that teams develop through a variety of alternative paths rather than a single sequence of developmental phases. These lines of thinking are integrated here in the form of a model called Team Evolution And Maturation (TEAM), which helps to guide consideration of the development of team performance. The results of an experimental investigation are presented as a preliminary test of the model's suggestion that team development is characterized by the differential maturation of taskwork and teamwork skills. Results indicate that task- and team-related activities were distinguishable in the middle phases of training, but not at the beginning and end of training. These findings are discussed in terms of their implications for investigations of team...

Process for determination of text relevancy

Abstract: This is a procedure for determining text relevancy and can be used to enhance the retrieval of text documents by search queries. This system helps a user intelligently and rapidly locate information found in large textual databases. A first embodiment determines the common meanings between each word in the query and each word in the document. Then an adjustment is made for words in the query that are not in the documents. Further, weights are calculated for both the semantic components in the query and the semantic components in the documents. These weights are multiplied together, and their products are subsequently added to one another to determine a real value number (similarity coefficient) for each document. Finally, the documents are sorted in sequential order according to their real value number from largest to smallest value. Another, embodiment is for routing documents to topics/headings (sometimes referred to as filtering). Here, the importance of each word in both topics and documents are calculated. Then, the real value number (similarity coefficient) for each document is determined. Then each document is routed one at a time according to their respective real value numbers to one or more topics. Finally, once the documents are located with their topics, the documents can be sorted. This system can be used to search and route all kinds of document collections, such as collections of legal documents, medical documents, news stories, and patents.

The Pocket Handbook of Imaging Processing Algorithms in C

Abstract: This handy desktop reference gathers together into one easy-to-use volume the most popular image processing algorithms. Designed to be used at the computer terminal, it features an illustrated, annotated dictionary format -- with clear, concise definitions, examples, and C program code.

Z-scan measurements of the anisotropy of nonlinear refraction and absorption in crystals

Abstract: We introduce a method for measuring the anisotropy of nonlinear absorption and nonlinear refraction in crystals by incorporating a wave plate into the Z-scan apparatus. We demonstrate this method by measuring the polarization dependence of the nonlinear refractive index or two-photon absorption coefficient in BaF2, KTP, and GaAs at wavelengths of 532 and 1064 nm.

Relations between Hermite and Laguerre Gaussian modes

Abstract: Relations between Hermite (HG) and Laguerre (LG) Gaussian modes are derived. With these, a LG mode is written as a sum of HG modes, and vice versa. These mode relations are derived from addition identities between a Laguerre polynomial and a pair of Hermite polynomials. The addition relations are derived in two appendices. One figure illustrates the contents of a LG mode in terms of HG modes while a second figure shows the translation in the opposite direction. >

Addition spectra of quantum dots in strong magnetic fields.

Abstract: We consider the magnetic field dependence of the chemical potential for parabolically confined quantum dots in a strong magnetic field. Approximate expressions based on the notion that the size of a dot is determined by a competition between confinement and interaction energies are shown to be consistent with exact diagonalization studies for small quantum dots. Fine structure is present in the magnetic field dependence which cannot be explained without a full many-body description and is associated with ground-state level crossings as a function of confinement strength or Zeeman interaction strength. Some of this fine structure is associated with precursors of the bulk incompressible states responsible for the fractional quantum Hall effect

What Do Russian Managers Really Do? An Observational Study with Comparisons to U.S. Managers

Abstract: Recent events have generated considerable interest, but little empirical evidence, in Russian management. This observation study of a sample of managers (N=66) in a large textile factory in Russia used the same definitions, methodology and procedures as a stream of research conducted by Luthans and his colleagues on U.S. "Real Managers" (see Luthans, Hodgetts and Rosenkrantz [1988]). Similar to American managers, the Russian managers in this factory were observed, in order, to perform traditional management, communication, human resources and networking activities. Also similar to the managers studied in the U.S., the Russian managers' networking activity generally related to their success. The relationship between the Russian managers' various activities and their effectiveness was less clear, but, like the American managers, the communication activity was a significant predictor across analysis techniques. The implications these findings have for Russia's transition to a market economy are discussed.

Large nonlinear phase modulation in quasi-phase-matched KTP waveguides as a result of cascaded second-order processes

Abstract: Nonlinear spectral modulation and broadening have been observed in quasi-phase-matched KTP waveguides near 850 nm, indicative of self-phase modulation that is due to cascaded second-order processes. Numerical beam-propagation simulations indicate nonlinear peak phase shifts larger than π for 600 W of peak power in a 2.8-mm-long guide.

Resource Allocation as an Outcropping of Strategic Consistency: Performance Implications

Abstract: Similarities in financial resource allocations across the lines of business of diversified firms may indicate corporate strategic consistency, which may lead to superior corporate performance. In s...

Modeling the benefits of advanced traveler information systems in corridors with incidents

Abstract: This paper concerns the benefits from Advanced Traveler Information Systems (ATIS) in corridors under incident conditions. A deterministic queueing model is developed and applied to an idealized corridor composed of two routes. A user optimal strategy is implemented to disseminate real-time traffic information to vehicles equipped with ATIS as they approach the incident bottleneck. The sensitivity of route guidance benefits to relevant parameters such as the fraction of vehicles guided with ATIS is analyzed. The findings show that a few cases of queue evolution result when ATIS is used under incident conditions. Both the proportion of guided traffic and the incident duration play an important role in determining which case results. When an incident occurs, ATIS will divert all equipped vehicles to the alternate route until equilibrium is achieved. Equilibrium is achieved only if a sufficient number of guided vehicles comply with diversion instructions. Equilibrium is maintained by reducing the rate of diversion from one route to the other. The implication is that during equilibrium some guided travelers will be diverted to the alternate route, while others will remain on the route where the incident has occurred. It is found that the benefits to guided traffic decrease when the proportion of guided traffic exceeds a critical value that causes a queue on the alternate route. The system benefits also level off once the critical value is exceeded. Therefore, if the system management has the choice, there is no need to equip more than the critical fraction of vehicles with ATIS. There is a need to develop a methodology that can find practical estimates of the critical fraction for use in large-scale simulations of real-life networks.

On the efficiency of parallel backtracking

Abstract: Analytical models and experimental results concerning the average case behavior of parallel backtracking are presented. Two types of backtrack search algorithms are considered: simple backtracking, which does not use heuristics to order and prune search, and heuristic backtracking, which does. Analytical models are used to compare the average number of nodes visited in sequential and parallel search for each case. For simple backtracking, it is shown that the average speedup obtained is linear when the distribution of solutions is uniform and superlinear when the distribution of solutions is nonuniform. For heuristic backtracking, the average speedup obtained is at least linear, and the speedup obtained on a subset of instances is superlinear. Experimental results for many synthetic and practical problems run on various parallel machines that validate the theoretical analysis are presented. >

Assessing some determinant effects of ethical consulting behavior: The case of personal and professional values

Abstract: A random sample of 207 national business consultants is employed to test the effects of individual values and professional ethics on consulting behavior. The results suggest that the individual values held by consultants are positively correlated with professional ethics, but are negatively correlated with consulting behavior. Moreover, there appears to be no significant relationship between the professional ethics of consultants and business consulting behavior. Findings and issues regarding the effectiveness of codes of ethics and implications for both the provider and recipient of professional consulting services are discussed.

Enhanced self-phase modulation in tapered fibers

Abstract: Fiber tapering reduces the effective area and increases the Kerr nonlinear phase shift of the fundamental mode. A significant nonlinear effect was observed in a micrometer-diameter centimeter-long section of tapered fiber at a wavelength of 1550 nm. The numerical simulation of a second-order soliton entering the taper gives a spectral widening that matches the observed spectrum.

Convective heat transfer at a stretching sheet

Abstract: Analysis of convection flow and heat transfer of a viscous heat-generating fluid near an infinite vertical stretching surface is carried out. The effects of free convection and the presence of heat generation/absorption on the flow and heat transfer characteristics are considered. The equations of conservation of momentum, mass, and energy, which govern the flow and heat transfer problem, are solved numerically by using a variable order, variable step size finite-difference method. The numerical results obtained for the flow and heat transfer characteristics reveal many interesting behaviors. These behaviors warrant further study of the effects of free convection on the flow and heat transfer characteristics.

Absorption and thermal conductivity of oxide thin films measured by photothermal displacement and reflectance methods.

Abstract: Photothermal reflectance and photothermal displacement measurements of optical absorption and thermal conductivity are reported for electron-beam-(EB) deposited and ion-plated (IP) thin films of TiO(2), Ta(2)O(5), and ZrO(2). Of the particular set of samples investigated, the EB films have higher absorption than the IP films. The absorption of the EB samples decreases over a period of ~ 90 min on irradiations with an Ar-ion laser of 488-nm wavelength. By contrast, the absorption of the IP samples changes insignificantly or not at all. Photothermal displacement area scans of coating surfaces yield lower defect densities for the IP samples compared with the EB samples for all three oxide materials. The feasibility and limitations of photothermal measurements for thin-film optical and thermal characterizations are discussed.

Career Advancement: Does Gender Make a Difference?

Abstract: Barriers to women's advancement in the public sector continue to be very real. Debate has shifted from concern about equal employment opportunity and access to entry- and middle-level leadership positions to an examination of the glass ceiling phenomenon, which prevents many women from reaching upper level management positions. Using a conceptual and analytical framework developed for my doctoral dissertation and data generated from a survey of 253 upper level administrators in the Florida State government, this paper compares the experiences of women to those of men in elite public management positions. The paper underscores the barriers women encounter as they attempt to advance their careers and argues that it is not gender difference, but rather the difference that gender makes that explains why these barriers persist.

Material figures of merit and implications to all-optical waveguide switching

Abstract: It is possible to define figures of merit which a nonlinear material must satisfy in order for it to be useful for all-optical switching in waveguides (as well as other nonlinear devices). Here we first discuss the physical basis for these figures of merit. Examples of materials in which these figures of merit both are and are not satisfied will be given. Finally the evolution of nonlinear directional couplers will be reviewed and the impact of figures of merit identified.

Computer imaging recipes in C

Abstract: Focusing on algorithm programming in C, this practical guide provides clear, concise treatment of the entire spectrum of image processing techniques. Without getting bogged down in complex mathematics, the book covers all aspects of imaging from basic characterization and modelling through grayscale and spatial manipulation techniques; powerful convolution, spatial frequency, and adaptive filtering methods; and each algorithm group discussed includes C program code to illustrate how the process is programmed.

Quasi-Closed-Form Solution to the Time-Optimal Rigid Spacecraft Reorientation Problem

Abstract: The problem of slewing a rigid body from an arbitrary initial orientation to a desired target orientation in minimum time is addressed. The nature of the time-optimal solution is observed via an open-loop solution using the switch time-optimization algorithm developed by Meier and Bryson. Conclusions as to the number and timing of control switches are drawn and substantiated analytically. The solution of the kinematic differential equations for Euler parameters is examined for systems in which the applied torque is much greater than the nonlinear terms in Euler's equations. An approximate solution to these equations is used to construct the state transition matrix as a function of a given control sequence and control intervals. This allows a rapid solution for the required switch times for all admissible control sequences. Uncoupled switching functions can be generated given the approximate switch times for the optimal sequence. The resulting feedforward/feedback control is suitable for online computation.