Showing papers by "University of Central Florida published in 1994"

Ethical decision making: A review of the empirical literature

Abstract: The authors review the empirical literature in order to assess which variables are postulated as influencing ethical beliefs and decision making. The variables are divided into those unique to the individual decision maker and those considered situational in nature. Variables related to an individual decision maker examined in this review are nationality, religion, sex, age, education, employment, and personality. Situation specific variables examined in this review are referent groups, rewards and sanctions, codes of conduct, type of ethical conflict, organization effects, industry, and business competitiveness. The review identifies the variables that have been empirically tested in an effort to uncover what is known and what we need to know about the variables that are hypothesized as determinants of ethical decision behavior.

Fostering Corporate Entrepreneurship: Cross-Cultural Comparisons of the Importance of Individualism Versus Collectivism

Abstract: This study reports on results of a cross-cultural, empirical investigation designed to assess the impact of individualism/collectivism upon organizational entrepreneurship. The findings indicate individualism/collectivism is an important factor in understanding entrepreneurial behavior in the firm. Implications of these findings are discussed.

A Psychometric Evaluation of 4-Point and 6-Point Likert-Type Scales in Relation to Reliability and Validity.

Abstract: Reliability and validity of 4-point and 6-point scales were assessed using a new model-based ap proach to fit empirical data. Different measurement models were fit by confirmatory factor analyses of a multitrait-multimethod covariance matrix. 165 gradu ate students responded to nine items measuring three quantitative attitudes. Separation of method from trait variance led to greater reduction of reliability and heterotrait-monomethod coefficients for the 6-point scale than for the 4-point scale. Criterion-related valid ity was not affected by the number of scale points. The issue of selecting 4- versus 6-point scales may not be generally resolvable, but may rather depend on the empirical setting. Response conditions theorized to in fluence the use of scale options are discussed to pro vide directions for further research. Index terms: Likert-type scales, multitrait-multimethod matrix, reli ability, scale options, validity.

Age classification from facial images

Abstract: The ability to classify age from a facial image has not been pursued in computer vision. This research addresses the limited task of age classification of a facial image into a baby, young adult, and senior adult. This is the first reported work to classify age, and to successfully extract and use natural wrinkles. We present a theory and practical computations for visual age classification from facial images, based on cranio-facial changes in feature-position ratios, and on skin wrinkle analysis. Three age groups are classified. >

Feed-forward neural networks

Abstract: One critical aspect neural network designers face today is choosing an appropriate network size for a given application. Network size involves in the case of layered neural network architectures, the number of layers in a network, the number of nodes per layer, and the number of connections. Roughly speaking, a neural network implements a nonlinear mapping of u=G(x). The mapping function G is established during a training phase where the network learns to correctly associate input patterns x to output patterns u. Given a set of training examples (x, u), there is probably an infinite number of different size networks that can learn to map input patterns x into output patterns u. The question is, which network size is more appropriate for a given problem? Unfortunately, the answer to this question is not always obvious. Many researchers agree that the quality of a solution found by a neural network depends strongly on the network size used. In general, network size affects network complexity, and learning time. It also affects the generalization capabilities of the network; that is, its ability-to produce accurate results on patterns outside its training set. >

Face detection using templates

Abstract: In the problem area of human facial image processing, the first computational task that needs to be solved is that of detecting a face under arbitrary scene conditions. Although some progress towards this has been reported in the literature, face detection remains a difficult problem. In this paper the authors report on a novel face-finding method that appears quite robust. First, "snakelets" are used to find candidate edges. Candidate ovals (face-locations) are then found from these snakelets using a voting method. For each of these candidate face-locations, the authors use a method introduced previously to find detailed facial features. If a substantial number of the facial features are found successfully, and their positions satisfy ratio-tests for being standard, the procedure positively reports the existence of a face at this location in the image.

Age Differences in Computer Anxiety: The Role of Computer Experience, Gender and Education

Abstract: Research in the area of computer anxiety has traditionally concentrated on the younger adult. In this study older adults (55 years and over) were compared to younger adults (30 years and under) on ...

The Development and Emergence of Services Marketing Thought

Abstract: Offers the personal interpretations of authors as participant‐observers together with a data‐based analysis of the evolution of the services marketing literature. Bibliographic analysis of more than 1,000 English language, general services marketing publications, spanning four decades, provides an additional resource. Using an evolutionary metaphor as the framework, traces the literature through three stages: Crawling Out (1953‐79): Scurrying About (1980‐85); and Walking Erect (1986‐present). Shows how the literature has evolved from the early services‐marketing‐is‐different debate to the maturation of specific topics (e.g. service quality, service encounters) and the legitimization of the services marketing literature by major journals. Presents a classification and summary of publications and authors. Closes with discussion and speculation on the future of the services marketing literature.

An ahp framework for prioritizing customer requirements in qfd: an industrialized housing application

Abstract: Construction of housing in the United States is highly decentralized. There is an increasing use of manufactured components and modules constructed off-site at a manufacturing facility and assembled at die building site. However, there has been little use of modern manufacturing processes and controls. In an effort to develop energy efficient, affordable industrialized housing, a total engineering design approach is needed. This study uses a concurrent engineering approach to examine the production of an essential component in industrialized housing, a manufactured exterior structural wall panel. In particular, we apply Quality Function Deployment to fully integrate the customer's requirements. This paper focuses on the identification and prioritization of those customer requirements. We integrate the Analytic Hierarchy process with QFD to establish a framework for prioritizing customer requirements.

Visual gesture recognition

Abstract: Presents a method for recognising human-hand gestures using a model based approach. A finite state machine is used to model four qualitatively distinct phases of a generic gesture. Fingertips are tracked in multiple frames to compute motion trajectories. The trajectories are then used for finding the start and stop position of the gesture. Gestures are represented as a list of vectors and are then matched to stored gesture vector models using table lookup based on vector displacements. Results are presented showing recognition of seven gestures using images sampled at 4 Hz on a SPARC-1 without any special hardware. The seven gestures are representatives for actions of left, right, up, down, grab, rotate, and stop.

Time-resolved Z-scan measurements of optical nonlinearities

Abstract: We introduce a temporal delay in one beam of the two-color Z-scan apparatus, which measures nondegenerate nonlinear absorption and nondegenerate nonlinear refraction. This technique allows us to time resolve separately the sign and the magnitude of the nonlinear absorption and refraction at frequency ωp that are due to the presence of a strong excitation at frequency ωe. For example, in semiconductors we specifically measure the bound electronic, nondegenerate nonlinear refraction and nondegenerate two-photon absorption, as well as the two-photon-generated free-carrier refraction and absorption as functions of time. We demonstrate this technique on ZnSe, ZnS, and CS2, using picosecond pulses at 1.06 and 0.532 μm.

Resonant converter topologies with three and four energy storage elements

Abstract: Generalized half-bridge and full-bridge resonant converter topologies with two, three and four energy storage elements are presented. All possible circuit topologies for such converters under voltage/current driven and voltage/current sinks are discussed. Many of these topologies have not been investigated in open literature. Based on their circuit element connections and source and load excitation types, these topologies are classified into resonant and nonresonant topologies and on their physical realizability. Comparison based on exact steady state analysis are given for typical second- and third-order series resonant converters whereas the fourth-order topology is based on the approximate analysis. >

Ultraviolet laser emission properties of Ce 3+ -doped LiSrAlF 6 and LiCaAlF 6

Abstract: The UV laser properties of trivalent cerium-doped LiSrAlF6 (Ce:LiSAF) and LiCaAlF6 (Ce:LiCAF) are reported. The polarized absorption, emission, and excited-state absorption cross sections for both Ce:LiSAF and Ce:LiCAF were determined for the 266-nm pump and 290-nm laser emission wavelengths. The single-exponential emission lifetime was measured to be 28 ± 2 and 25 ± 2 ns for Ce:LiSAF and Ce:LiCAF, respectively. The gain was found to be highest when the probe was polarized parallel to the optical axis of the crystal, owing to the anisotropic nature of the excited-state absorption. The excited-state absorption was ascribed to a transition from the 5d orbital of Ce3+ to the conduction band of the host. Laser slope efficiencies as high as 29% and 21%, respectively, were measured for Ce:LiSAF and Ce:LiCAF when the 266-nm pulsed pump beam was polarized parallel to the optical or the c axis. These are the highest laser slope efficiencies yet observed to our knowledge for any known solid-state UV laser material. When the pump beam was polarized perpendicular to the optical axis of the crystals, the gain and the laser efficiencies dropped by as much as an order of magnitude. The magnitude of pump-induced solarization was found to be highly variable for different crystals and to have an insignificant effect on the laser performance when favorable crystals were used.

Eclipsing Z-scan measurement of λ/10 4 wave-front distortion

Abstract: We introduce a simple modification to the Z-scan technique that results in a sensitivity enhancement that permits measurement of nonlinearly induced wave-front distortion of ≃λ/104. This sensitivity was achieved with 10-Hz repetition-rate pulsed laser sources. Sensitivity to nonlinear absorption is also enhanced by a factor of ≃3. This method permits characterization of nonlinear thin films without the need for waveguiding.

Solitary waves due to χ (2) :χ (2) cascading

Abstract: Solitary waves in materials with a cascaded χ(2):χ(2) nonlinearity are investigated, and the implications of the robustness hypothesis for these solitary waves are discussed. Both temporal and spatial solitary waves are studied. First, the basic equations that describe the χ(2):χ(2) nonlinearity in the presence of dispersion or diffraction are derived in the plane-wave approximation, and we show that these equations reduce to the nonlinear Schrodinger equation in the limit of large phase mismatch and can be considered a Hamiltonian deformation of the nonlinear Schrodinger equation. We then proceed to a comprehensive description of all the solitary-wave solutions of the basic equations that can be expressed as a simple sum of a constant term, a term proportional to a power of the hyperbolic secant, and a term proportional to a power of the hyperbolic secant multiplied by the hyperbolic tangent. This formulation includes all the previously known solitary-wave solutions and some exotic new ones as well. Our solutions are derived in the presence of an arbitrary group-velocity difference between the two harmonics, but a transformation that relates our solutions to zero-velocity solutions is derived. We find that all the solitary-wave solutions are zero-parameter and one-parameter families, as opposed to nonlinear-Schrodinger-equation solitons, which are a two-parameter family of solutions. Finally, we discuss the prediction of the robustness hypothesis that there should be a two-parameter family of solutions with solitonlike behavior, and we discuss the experimental requirements for observation of solitonlike behavior.

Artificial uniaxial and biaxial dielectrics with use of two-dimensional subwavelength binary gratings

Abstract: Two-dimensional symmetric and asymmetric subwavelength binary gratings are investigated. A method for determining the three effective indices of a two-dimensional (2-D) subwavelength grating is presented, as well as a theoretical formalization for the effective index parallel with the normal to the surface. It is shown that a 2-D asymmetric binary grating on the surface of a dielectric substrate is analogous to a biaxial thin film. If the grating is symmetric, then the two effective indices perpendicular to the normal are equal, and the grating is analogous to a uniaxial thin film. Using these effective indices and the quarter-wave Tschebyscheff synthesis technique, we designed two- and three-level binary gratings to suppress reflections over a broad band. It is shown that for a substrate index of ns = 3.0 a three-level 2-D binary grating reduced reflections below 0.1% from 8 μm to 12 μm.

Determining the Dimensionality in Sliced Inverse Regression

Abstract: A general regression problem is one in which a response variable can be expressed as some function of one or more different linear combinations of a set of explanatory variables as well as a random error term. Sliced inverse regression is a method for determining these linear combinations. In this article we address the problem of determining how many linear combinations are involved. Procedures based on conditional means and conditional covariance matrices, as well as a procedure combining the two approaches, are considered. In each case we develop a test that has an asymptotic chi-squared distribution when the vector of explanatory variables is sampled from an elliptically symmetric distribution.

The virtual environment performance assessment battery vepab: Development and evaluation1

Abstract: The Virtual Environment Performance Assessment Battery VEPAB is a set of tasks developed to support research on training applications of virtual environment VE technology. VEPAB measures human performance on vision, locomotion, tracking, object manipulation, and reaction time tasks performed in three-dimensional, interactive VEs. It can be used to provide a general orientation for interacting in VEs and to determine both entry level performance and skill acquisition of users. In addition, VEPAB allows comparison of task performance, side effects and aftereffects, and subjective reactions across different VE systems. By providing benchmarks of human performance, VEPAB can promote continuity in training research involving different technologies, separate research facilities, and dissimilar subject populations. This paper describes the development of VEPAB and summarizes the results of two experiments, one to test the sensitivity of the tasks to differences between input control devices and the other to examine practice effects.

Recognizing hand gestures

Abstract: This paper presents a method for recognizing human-hand gestures using a model-based approach. A Finite State Machine is used to model four qualitatively distinct phases of a generic gesture. Fingertips are tracked in multiple frames to compute motion trajectories, which are then used for finding the start and stop position of the gesture. Gestures are represented as a list of vectors and are then matched to stored gesture vector models using table lookup based on vector displacements. Results are presented showing recognition of seven gestures using images sampled at 4 Hz on a SPARC-1 without any special hardware. The seven gestures are representatives for actions of Left, Right, Up, Down, Grab, Rotate, and Stop.

Limits of scalar diffraction theory for diffractive phase elements

Abstract: The range of validity and the accuracy of scalar diffraction theory for periodic diffractive phase elements (DPE’s) is evaluated by a comparison of diffraction efficiencies predicted from scalar theory to exact results calculated with a rigorous electromagnetic theory. The effects of DPE parameters (depth, feature size, period, index of refraction, angle of incidence, fill factor, and number of binary levels) on the accuracy of scalar diffraction theory is determined. It is found that, in general, the error of scalar theory is significant (∊ > ±5%) when the feature size is less than 14 wavelengths (s < 14λ). The error is minimized when the fill factor approaches 50%, even for small feature sizes (s = 2λ); for elements with an overall fill factor of 50% the larger period of the DPE replaces the smaller feature size as the condition of validity for scalar diffraction theory. For an 8-level DPE of refractive index 1.5 analyzed at normal incidence the error of the scalar analysis is greater than ±5% when the period is less than 20 wavelengths (Λ < 20λ). The accuracy of the scalar treatment degrades as either the index of refraction, the depth, the number of binary levels, or the angle of incidence is increased. The conclusions are, in general, applicable to nonperiodic as well as other periodic (trapezoidal, two-dimensional) structures.

Efficient Continuous Wave-laser emission of Pr3+-doped fluorides at room temperature

Abstract: We report, to our knowledge for the first time, Continuous Wave (CW) laser emission at room temperature of Pr:LiYF4 (Pr.YLF) at six wavelengths: 522, 545, 607, 639.5, 720 and 907.4 nm. The pump source was an argon-ion laser tuned to a wavelength of ⋋ = 457.9 nm. The maximum output powers at 522 nm (3Pi →3H5) and 639.5 nm (3P0 →3F2) were 144 and 266 mW, respectively. We also observed CW laser action of Pr:GdLiF4 (Pr: GLF) at λ = 639 nm and of Pr:KYF4 (Pr: KYF) at λ = 642.5 nm.

Equity sensitivity and outcome importance

Abstract: Equity theory (Adams, 1963, 1965) is a common theory used to explain employee behavior. Four basic points capture the thrust of the theory. (a) Individuals evaluate their relationships with others (e.g. their employers) by assessing the ratio of the outcomes they receive in the relationship and the inputs to the relationship against the outcome/input ratio of a comparison other. (b) This comparison other may be a co-worker, a peer working for another employer, a collective other such as a composite standard based on peers or the industry averages, the employer as a whole, oneself in another social role such as a previous job, or some type of internal standard. (c) If the perceived outcome/input ratios of the individual and comparison other are perceived to be unequal, then inequity exists. (d) This inequity causes tension frustration of underreward or guilt of overreward. In simplest terms, equity theory proposes that when individuals feel inequitably rewarded, internal tension occurs and individuals will be motivated to take action to restore equity, thereby relieving the tension. Soon after its introduction by Adams, equity theory gained early support and research attention. Weick even went as far as to label it as being 'among the most useful middle-range theories of organizational behavior' (1966, p. 439). However, early equity theory research resulted in

Religiousness, Religious Orientation, and Attitudes Towards Gays and Lesbians1

Abstract: Two studies are reported that examine the relationships among religiousness, religious orientation, and prejudice toward gays and lesbians Study 1 reports the results of a survey done for the purposes of scientific jury selection These results suggest that Baptists, fundamentalists, and “Christians” display more antigay prejudice than do Catholics, Jews, and many Protestant denominations, but even many supporters of gay-tolerant religions show more antigay prejudice than those claiming no religious preference Among those with a religious preference, frequency of worship is significantly related to antigay prejudice among those belonging to antigay denominations, but not among those belonging to more gay tolerant religious faiths Study 2 reports the results of a study of college students regarding religiousness, religious orientation, and prejudice toward gays and lesbians Results showed that self reported religiousness, frequency of worship, and Batson's internal and external scales were all positively correlated with measures of prejudice toward gays and lesbians, whereas scores on the Quest (Interactional) scale were negatively correlated Results of both studies strongly challenge the view that those with an intrinsic religious orientation are unprejudiced It is argued that a social influence process can account for the role played by religious practice and beliefs in creating and maintaining negative attitudes toward gays and lesbians

Maintenance Scheduling: Issues, Results and Research Needs

Abstract: Productivity, based on estimated and actual hours, of most maintenance workers is only 30 to 50 per cent. Given the significance of maintenance to manufacturing competitiveness, it is surprising how little research is being carried out. Scheduling is a crucial component of maintenance management and is a focus of research. Identifies the areas of concern in maintenance scheduling and surveys representative work from the academic and practitioner literature. Specific points of practice and theory which need further investigation are pinpointed.

A historical examination of small business management and entrepreneurship pedagogy

Abstract: Four national surveys on course offerings and pedagogies in entrepreneurship and small business management were conducted by the U.S. Small Business Administration (SBA) in 1979, 1982, 1986, and 1992. The data are summarized, providing historical information in terms of the number of responses received and the major teaching pedagogies used by both 4-year colleges and universities and 2-year community and junior colleges. Tables are provided that reflect a definite growth pattern in small business management and entrepreneurship course offerings at both 4-year and 2-year schools. Tables also are provided that indicate the extent and use of various teaching and evaluation pedagogies used by these academic institutions.

Identification and Role of Two-Photon Excited States in a π -Conjugated Polymer

Abstract: We have measured the full two-photon absorption (TPA) spectrum in the transparency range of single-crystal polydiacetylene paratoluene-sulfonate (PTS) using $z$ scan. The spectrum consists of three well-defined two-photon excited states superimposed on a continuum of even-parity states. Comparison of the TPA and the one-photon absorption spectra identifies a two-photon accessible state as the lowest excited state of PTS. The accompanying dispersion in the intensity-dependent refractive index coefficient ${n}_{2}$ is also reported.