Showing papers by "University of Central Florida published in 1999"

Shape-from-shading: a survey

Abstract: Since the first shape-from-shading (SFS) technique was developed by Horn in the early 1970s, many different approaches have emerged. In this paper, six well-known SFS algorithms are implemented and compared. The performance of the algorithms was analyzed on synthetic images using mean and standard deviation of depth (Z) error, mean of surface gradient (p, q) error, and CPU timing. Each algorithm works well for certain images, but performs poorly for others. In general, minimization approaches are more robust, while the other approaches are faster.

Stakeholders, social responsibility, and performance: empirical evidence and theoretical perspectives

Abstract: The management of competing stakeholder interests has emerged as a significant topic in the management literature. Related issues are the relationship between stakeholder management and the perception that a firm is socially responsible, and the performance implications of both stakeholder management and social responsibility. Theory and models surrounding these issues are abundant, but empirical research is in an early stage. This research forum reports six excellent efforts to tackle fundamental ideas about stakeholders, social responsibility, and performance.

Optical Spatial Solitons and Their Interactions: Universality and Diversity.

Abstract: Spatial solitons, beams that do not spread owing to diffraction when they propagate, have been demonstrated to exist by virtue of a variety of nonlinear self-trapping mechanisms. Despite the diversity of these mechanisms, many of the features of soliton interactions and collisions are universal. Spatial solitons exhibit a richness of phenomena not found with temporal solitons in fibers, including effects such as fusion, fission, annihilation, and stable orbiting in three dimensions. Here the current state of knowledge on spatial soliton interactions is reviewed.

Customer satisfaction and its measurement in hospitality enterprises

Abstract: Reviews and discusses the topic of customer satisfaction and its application to the hospitality and tourism industries. Defines the concept and analyzes its importance to services in general and to hospitality/tourism services in particular. Following a discussion on the dimensions and attributes of satisfaction, lists the main methods of measuring satisfaction and concludes with a review of global and cross‐cultural issues that affect satisfaction.

Efficacy of relapse prevention: a meta-analytic review

Abstract: Although relapse prevention (RP) has become a widely adopted cognitive-behavioral treatment intervention for alcohol, smoking, and other substance use, outcome studies have yielded an inconsistent picture of the efficacy of this approach or conditions for maximal effectiveness. A meta-analysis was performed to evaluate the overall effectiveness of RP and the extent to which certain variables may relate to treatment outcome. Twenty-six published and unpublished studies with 70 hypothesis tests representing a sample of 9,504 participants were included in the analysis. Results indicated that RP was generally effective, particularly for alcohol problems. Additionally, outcome was moderated by several variables. Specifically, RP was most effective when applied to alcohol or polysubstance use disorders, combined with the adjunctive use of medication, and when evaluated immediately following treatment using uncontrolled pre-post tests.

Entrepreneurship in Established Organizations: The Case of the Public Sector

Abstract: The potential role of entrepreneurship in public sector organizations is explored. Entrepreneurship is conceptualized as a manageable process with underlying dimensions of innovativeness, risk-taki...

Theory of optical scintillation

Abstract: A heuristic model of irradiance fluctuations for a propagating optical wave in a weakly inhomogeneous medium is developed under the assumption that small-scale irradiance fluctuations are modulated by large-scale irradiance fluctuations of the wave. The upper bound for small turbulent cells is defined by the smallest cell size between the Fresnel zone and the transverse spatial coherence radius of the optical wave. A lower bound for large turbulent cells is defined by the largest cell size between the Fresnel zone and the scattering disk. In moderate-to-strong irradiance fluctuations, cell sizes between those defined by the spatial coherence radius and the scattering disk are eliminated through spatial-frequency filtering as a consequence of the propagation process. The resulting scintillation index from this theory has the form σI2=σx2+σy2+σx2σy2, where σx2 denotes large-scale scintillation and σy2 denotes small-scale scintillation. By means of a modification of the Rytov method that incorporates an amplitude spatial-frequency filter function under strong-fluctuation conditions, tractable expressions are developed for the scintillation index of a plane wave and a spherical wave that are valid under moderate-to-strong irradiance fluctuations. In many cases the models also compare well with conventional results in weak-fluctuation regimes. Inner-scale effects are taken into account by use of a modified atmospheric spectrum that exhibits a bump at large spatial frequencies. Quantitative values predicted by these models agree well with experimental and simulation data previously published. In addition to the scintillation index, expressions are also developed for the irradiance covariance function of a plane wave and a spherical wave, both of which have the form BI(ρ)=Bx(ρ)+By(ρ)+Bx(ρ)By(ρ), where Bx(ρ) is the covariance function associated with large-scale fluctuations and By(ρ) is the covariance function associated with small-scale fluctuations. In strong turbulence the derived covariance shows the characteristic two-scale behavior, in which the correlation length is determined by the spatial coherence radius of the field and the width of the long residual correlation tail is determined by the scattering disk.

High-efficiency bragg gratings in photothermorefractive glass.

Abstract: Photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine were fabricated at the Center for Research and Education in Optics and Lasers. Bragg diffractive gratings were recorded in the volume of these glasses with a photothermorefractive process (exposure to UV radiation of a He–Cd laser at 325 nm is followed by thermal development at 520 °C). Absolute diffraction efficiency of as much as 93% was observed for 1-mm-thick gratings with spatial frequencies up to 2500 mm-1. No decreasing of diffraction efficiency was detected at low spatial frequencies. Original glasses were transparent (absorption coefficient less than 1 cm-1) from 350 to 4100 nm. Induced losses in exposed and developed glass decreased from 0.3 to 0.03 cm-1 between 400 and 700 nm, respectively, and did not exceed 0.01–0.02 cm-1 in the IR region from 700 to 2500 nm. Additional losses caused by parasitic structures recorded in the photosensitive medium were studied.

A Comprehensive Approach to Classifying Acts of Crime and Violence at Tourism Destinations

Abstract: Based on a review of 300 cases of acts of crimes and violence that occurred at tourist destinations around the world in the last decade, a comprehensive typology was created. The objectives of this typology were to classify the attributes of acts of crime and violence, to analyze the differential effects that such attributes have on tourism demand, to examine the effectiveness of methods used for prevention and recovery from such acts, and to identify the parties responsible for prevention and recovery.

Segmenting Tourism in Rural Areas: The Case of North and Central Portugal

Abstract: The primary purpose of this study was to segment and profile the needs of rural tourists so as to provide a better understanding of rural tourism in Portugal. A self-administered survey in four languages was obtained from 200 visitors in the study area. Four useful benefit segments were identified, and implications for market development are discussed.

Task scheduling algorithms for heterogeneous processors

Abstract: Scheduling computation tasks on processors is the key issue for high-performance computing. Although a large number of scheduling heuristics have been presented in the literature, most of them target only homogeneous resources. The existing algorithms for heterogeneous domains are not generally efficient because of their high complexity and/or the quality of the results. We present two low-complexity efficient heuristics, the Heterogeneous Earliest-Finish-Time (HEFT) algorithm and the Critical-Path-on-a-Processor (CPOP) algorithm for scheduling directed acyclic weighted task graphs (DAGs) on a bounded number of heterogeneous processors. We compared the performances of these algorithms against three previously proposed heuristics. The comparison study showed that our algorithms outperform previous approaches in terms of performance (schedule length ratio and speedup) and cost (time-complexity).

A Routine Activity Theory Explanation for Women's Stalking Victimizations:

Abstract: Drawing on surveys administered to 861 university women in nine institutions, this article presents a routine activity theory model for predicting stalking victimization likelihood for women. Using routine activity theory, the model highlights lifestyle behaviors and interactions as predictors of stalking victimization. Whereas routine activity theory often highlights the role of demographics and statuses as predictors, this analysis emphasizes the role of women's social interactions and substance use in victimization risk. Significant predictors of victimization likelihood include substance use variables, activities in public settings, and residence off campus.

Strength and ductility of concrete encased composite columns

Abstract: Concrete encased composite column design provisions of the American Concrete Institute Code (ACI 318), AISC-LRFD Specification, and the AISC Seismic Provisions are reviewed and evaluated based on fiber section analyses that account for the inelastic behavior of steel and concrete, including the effects of strength and confinement on the concrete's stress-strain properties. Trial column designs are analyzed to evaluate their strength and ductility as a function of the ratio of structural steel to gross column area, the nominal compression strength of concrete, and confinement of concrete by seismic hoop reinforcing. The analyses highlight known differences in the calculated nominal strength requirements between the ACI 318 and AISC-LRFD provisions and suggest a review of criteria used to establish the limits of the provisions. Compared to columns with low- to medium-strength concrete, columns with high-strength concrete (fc′ = 110 MPa) are shown to rely to a greater degree on hoop reinforcement to provide ...

Non-linear optical properties of chalcogenide glasses in the system As S Se

Abstract: We report results of a systematic study examining the relationship of bond type and concentration to the linear and non-linear optical properties of As–S–Se glasses. The effects of iso-structural substitution of Se for S and the resulting impact on structure and the non-linear refractive index, n 2 , are discussed. Non-linear optical properties of As–S–Se chalcogenide glasses were measured by the Z-scan technique at 1.6 μm, and measured n 2 up to 400 times the n 2 for silica were observed. Such large n 2 for glasses with small As/(S + Se) molar ratios is correlated with the presence of covalent, homopolar Se–Se bonds in the glass structure as identified by Raman spectroscopy, and can not be attributed to any red shift in the absorption edge or to a resonant effect. The suitability of these glasses for planar waveguides based on such nonlinear properties is thus confirmed, and recent fabrication results are described.

Cognitive packet networks

Abstract: We propose cognitive packet networks (CPN) in which intelligent capabilities for routing and flow control are concentrated in the packets, rather than in the nodes and protocols. Cognitive packets within a CPN route themselves. They are assigned goals before entering the network and pursue these goals adaptively. Cognitive packets learn from their own observations about the network and from the experience of other packets with whom they exchange information via mailboxes. Cognitive packets rely minimally on routers. This paper describes CPN and shows how learning can support intelligent behavior of cognitive packets.

Non-invasive method and low-coherence apparatus system analysis and process control

Abstract: The disclosure relates to measuring devices that are particularly suited for the purpose of in-situ characterization of particles present in fluid substances or in air using a low-coherence interferometer. Specifically, the characterization includes average size, size distribution, volumetric density, and composition. The low-coherence interferometer utilizes a split band of radiation to illuminate a sample probe and a reference probe then combines the reflected radiation from both probes to determine the photon pathlength distribution of the tested particulate or colloidal containing stream and from this information determine the size characteristics of said stream. The methodology is relevant to possible spatially distributed control of chemical processes such as emulsion polymerization to produce paints, coatings, synthetic rubbers, or crystallization processes in pharmaceuticals, food, and bulk chemicals industries. Another application relates to on-line control of particle size and volumetric density is in combustion for diagnostics. The invention can be used for the characterization of coal particles, dense sprays and solid propellants or any other system, which is too dense for conventional optical measurement techniques. Beside the intrinsic particulate nature of these systems, random index of refraction variations are also created due to turbulence/temperature interactions. The remote optical characterization of systems with high-concentration of suspended solids is also important for water quality control and pollution monitoring.

Price Information and Bidding Behavior in Repeated Second-Price Auctions

Abstract: Examining panel data on bidding behavior in over forty second-price auction markets with repeated trials, we observe that (i) posted prices influence the behavior of the median naive bidder; (ii) posted prices do not affect the behavior of the median experienced bidder or the bidder for familiar goods; and (iii) anticipated strategic behavior wanes after two trials. The results suggest that while affiliation might exist in auctions for new goods, the repeated trial design with nonprice information removes the correlation of values and provides the experience that bidders need to understand the market mechanism.

Fabrication and characterization of integrated optical waveguides in sulfide chalcogenide glasses

Abstract: This paper reports on the fabrication process of As-S-(Se)-based chalcogenide glass optical waveguides using three techniques: photolithography, laser beam writing, and ion implantation. The fabrication method of the bulk sulfide glasses and the processing of integrated devices are described and assessed in light of the propagation characteristics and optical losses in each case.

Survey of Job Shop Scheduling Techniques

Abstract: The sections in this article are 1 Introduction 2 Mathematical Techniques 3 Dispatching Rules 4 Artificial Intelligence (AI) Techniques 5 Artificial Neural Networks 6 Neighborhood Search Methods 7 Fuzzy Logic 8 Swarm 9 Reactive Scheduling 10 Learning in Scheduling 11 Theory of Constraints 12 Summary and Conclusions

Does crm training improve teamwork skills in the cockpit?: two evaluation studies

Abstract: Crew resource management (CRM) has been the most widely used instructional strategy to enhance teamwork skills within aviation. However, few studies have provided empirical evidence that this strategy results in increased use of teamwork behaviors. The current paper describes 2 evaluation studies of CRM training that were conducted with 96 naval aviators and followed a multiple assessment approach. Results indicated that highly experienced aviators benefited from the training, which focused on increasing the use of several critical teamwork skills. These rare evaluation data suggest that CRM training is a viable strategy for improving teamwork in the cockpit. Implications for team training are discussed.

Body Image, Psychological Functioning, and Parental Feedback Regarding Physical Appearance

Abstract: Objective To investigate the role of parental appearance-related commentary, body image, and psychological functioning in females and males. Method Retrospective reports of teasing and appearance-based feedback were assessed, along with current levels of body image and overall psychological functioning. Results Women and men did not differ in their reports of comments received from mothers, however, women received significantly more appearance-related messages from fathers. Correlational analyses demonstrated significant relationships between feedback and body satisfaction for women, but not for men. Regression analyses indicated that fathers' and mothers' teasing about weight were predictive of daughters' body image. For both males and females, psychological functioning was significantly predicted from the combination of mothers' and fathers' feedback regarding appearance. Discussion The findings further support an emerging theoretical model of appearance-related commentary as a factor in body image disturbance and overall psychological functioning. © by John Wiley & Sons, Inc. Int J Eat Disord 25: 339–343, 1999.

The effects of information management policies on reactions to human resource information systems: an integration of privacy and procedural justice perspectives

Abstract: The goal of the present study was to extend research on information privacy and fairness by examining these constructs within the context of human resource information systems. Using a 2 × 2 experimental design and data from 124 employed subjects in an organization that was in the process of developing a human resource information system, the present study examined the main and interactive effects of policies concerning ability to authorize disclosure (ability to authorize vs. no ability to authorize) and target of disclosure (internal to the organization vs. external to the organization) on invasion of privacy perceptions and fairness perceptions. Results of multivariate and univariate analyses of variance indicated that the independent variables had main and interactive effects on both fairness perceptions and invasion of privacy perceptions. Moreover, a confirmatory factor analysis suggested that invasion of privacy perceptions and fairness perceptions are distinct constructs. Implications of these findings for theory and practice are discussed.

International Expansion of Telecommunication Carriers: The Influence of Market Structure, Network Characteristics, and Entry Imperfections

Abstract: This paper examines the internationalization process of telecommunication carriers. In this industry, early entrants gain substantial first-mover advantages due to the transient nature of the windows of market opportunity, and the potential to influence the regulatory process as an incumbent. To capture these strategic and economic advantages, firms follow a strategy of preemption, both of markets and partners. The authors argue for the need to augment prevailing theory with contextual idiosyncrasies that characterize specific industries.

A Learning Framework for Project Management

Abstract: The contribution of this paper is a framework for understanding and practicing learning in a project environment. The framework includes the goals, processes, and tools for learning. The project ma...