Now showing items 14538-14557 of 14815

    • Visible Light Communications Using Four-Color LEDs

      Djordjevic, Ivan B.; Vangapandu, Sai Rakesh Mohan Krishna; Kost, Alan; Kilper, Dan (The University of Arizona., 2018)
      Visible light communications (VLC) technology has gained prominence in the development of high data rate transmission for the fifth generation (5G) networks. VLC technology can be used in conjunction with the existing Wi-Fi technology to improve access and data transmission. In optical wireless communications, LED transmitters are used in applications that desire mobility and the LED divergence enable larger coverage. VLC systems offer simultaneous data transmission and illumination. However, the LED’s limited modulation bandwidth and non-linear distortions pose difficulty in achieving high transmission data rates. Wavelength division multiplexing in VLC (WDM-VLC) can be used improve the data rates to meet gigabit data standards. This thesis work focuses on VLC experiments using WDM, discrete multitone modulation (DMT), and multi-input multi-output (MIMO) techniques. The VLC system is demonstrated over commercial four-color red-green-blue-amber (RGBA) LED transmitters in three cases of interest: (a) a single LED transmitter, (b) repetition encoding, and (c) spatial multiplexing. Our proposed VLC system used bit-power allocation strategies to maximize the data transmission under bit error rate (BER) threshold of 2×10-3, which is the typical hard-decision forward error correction (FEC) threshold.
    • The visible spectrum: as employed in theatrical lighting

      Montgomery, Gary Howard, 1944- (The University of Arizona., 1970)
    • Vision-based Upper Extremity Kinematic Analysis of Badminton Smash Hit

      Chan, Cho L.; Yang, Xiang; Poursina, Mohammad; Nikravesh, Parviz (The University of Arizona., 2019)
      Badminton is one of the fastest sports in the world. Athletes’ body rotations introduce a lot more complexities for studying badminton. The goal of this work is to develop a series of analysis including designing MATLAB programs and acquire kinematics data of badminton sport to help badminton players improve their skills. To validate these analyses are consistent with what badminton coaches teach athletes, interviews are conducted with coaches at the collegiate level to set commonly agreed “coaching points”. A full body marker setup is applied to this study while the markers are hand-made to reduce the weight and improve accuracy. 6 badminton players in different skill levels are brought in for data collecting. Subjects are asked to perform a smash motion as a return of a high and long badminton serving. Smashing data was captured by an eight-camera Vicon Motion Capture System (Nexus 1.8.5), and one video camera. Analyses were programmed by MATLAB to examine coaching points: speed and acceleration of shuttlecock and racket, contact point on racket net surface, coefficient of momentum transfer, coefficient of restitution, the angle between racket surface direction, racket moving direction, and angular velocity contributions from body parts. The results indicate the experiments and analysis are successful. Most of the ”coaching points” are proved by comparing kinematic quantities from players. These kinematic quantities can be applied as indicators to show the skill level of a player. With further development of this research, the coaching system can provide a series of dynamic analysis and lively visualized feedback to the athlete.
    • Visioning: A Public Participation Process for Community Building

      Rodgers, Christienne (The University of Arizona., 1997)
    • The visiting nurse staff and the psychosocial needs of the dying patient

      Sawyer, Susan Jane, 1942- (The University of Arizona., 1974)
    • Visitor attitudes and perceptions of use management in Rocky Mountain National Park

      Shaw, William W.; Beidleman, Carol Aileen, 1956- (The University of Arizona., 1988)
      Increasing visitation to national parks and the resulting resource impact has caused many park administrators to implement restrictive use management strategies. Though it seems clear that the resource has benefited from these use restrictions, little research has been done to determine their effect on the visitor. The goal of this study was to provide information to help guide the administrators of Rocky Mountain National Park in evaluating current use management actions and developing new ones in the future to both satisfactorily meet the protection needs of the resource and protect the quality of the visitor experience. Frontcountry campers were surveyed to determine awareness and attitudes about current and possible use management actions, perceptions of national park management purpose and challenges, and socio-demographic information. Respondents favored the majority of current use management actions, but were opposed to strongly restrictive actions considered as a possibility in the future.
    • Visitor behavior in zoo exhibits with underwater viewing: An evaluation of six exhibits in the western United States

      Livingston, Margaret; Ridgway, Stephanie Clark (The University of Arizona., 2000)
      The design of zoo and aquarium exhibits has a strong influence on visitor behavior in exhibit enclosures. Furthermore, zoo exhibits with underwater viewing draw large crowds. The intent of this study was to formulate significant design criteria, through post-occupancy evaluation, to be used for the design of successful underwater exhibits in zoos. This study was conducted to reveal factors significantly influencing viewing time and visitor behavior in zoo exhibits with underwater viewing. At four zoo facilities, 331 visitor groups were observed and asked to participate in a short survey at six zoo exhibits. Chi-square analysis and analysis of variance (ANOVA) were used to evaluate observation and survey results. The size of the underwater viewing window, animal size, animal aquatic activity, presence of infant animals, visitor group type and crowding levels had a significant impact on visitor behavior. Recommendations for the future design of underwater zoo exhibits are discussed.

      Autore, David Edward (The University of Arizona., 1984)
    • Visitors to America in pre-Columbian time

      Deloria, Vine, Jr.; Stanton, Kevin, 1955- (The University of Arizona., 1990)
      In the present era, scientists and researchers have gathered together a considerable amount of evidence which putatively demonstrates that contact occurred between the Old and New Worlds far in advance of either Columbus or the Vikings. This paper will describe and examine a small part of this evidence as well as provide a background summary of how pre-Columbian history was constructed. The emphasis of this paper reveals how epigraphic research has become the principle element in current investigations.
    • Vista scenic beauty estimation model: An application of integrating neural net and geographic information system

      Gimblett, Randy H.; Yuan, Yulan (The University of Arizona., 1998)
      There are some issues that have to be addressed for further understanding and improving scenic beauty management. First, the conventional model, preference rating based on fixed scene and direction, may not sufficiently reflect the reality of visual experience. Rather, visual and scenic preference is construed of a spatial experience. Second, the predictors are chosen based on measuring the composition of landscape features shown in the image. The measurement may not necessarily represent the contents of the physical environment. Third, judgements of scenic preference are complicated tasks. Simple linear regression analysis, with limited degree of freedom and some statistical constraints, may not represent the complexity of human judgments. An integrated model was developed by integrating the Scenic Beauty Estimation (SBE) model (Terry, 1976), the geographic information system (GIS) and, the artificial neural network (ANN). The results suggested the integrated model might be utilized as an automatic scenic preference mechanism for policy making. Implications for future research are also suggested.
    • Visual aids in health education

      Waggoner, Charles Ilo, 1907- (The University of Arizona., 1940)
    • The visual arts in Reform Jewish supplemental education: Art education beliefs and practices in context

      Galbraith, Lynn; Knoblock, Stacey Lee, 1969- (The University of Arizona., 1995)
      This thesis examines the context, content and pedagogy of visual art education in the Reform Jewish supplemental religious school. The study was guided by three major research questions: (1) What beliefs about art education are held by Reform Jewish educators? (2) What is the form and content of existing art education practices in the supplemental religious school setting? (3) What do these Reform Jewish educators perceive as necessary for the enhancement of the art education component of their curriculum? A study of a Reform Jewish supplemental school was conducted by myself as a teacher/researcher. Also, a sample of professional Reform Jewish educators was surveyed to determine art education beliefs and practices in the supplemental religious school setting. Survey results suggest a discrepancy between survey participants beliefs and practices in art education and those advocated by art educators. Contextual factors common to these settings are found to hinder possibilities for comprehensive visual arts education in the supplemental religious school. The study asserts that Jewish art education curricula must be developed from a discipline-based art education perspective in order to use instructional time most effectively.
    • Visual Attention to the Clinician's Face and Morpheme Acquisition during Conversational Recast Treatment

      Plante, Elena; Glickman, Alana; Kapa, Leah; Alt, Mary (The University of Arizona., 2019)
      Purpose. Enhanced Conversational Recast treatment is an input-based language therapy technique designed to help children with language disorders acquire missing grammatical morphemes in their speech. This version of conversational recast treatment requires clinicians to obtain the child’s attention before delivering each recast. This study examined the relationship between children’s looking behaviors in response to the clinician’s attentional cues and target morpheme acquisition. Method. Children received approximately 5 conversational recast treatment sessions per week for a total of 5 weeks. Progress was monitored through generalization probes assessing target morpheme use in untreated contexts. Video recordings of sessions were coded for children’s visual attention to their clinician’s face during the delivery of each treatment dose (i.e., recast). Reliability of coding was high. Results. Correlations between looking behaviors in response to attentional cues and performance on measures of generalization of morpheme use indicated a significant but negative association. Discussion. The results suggest that providing attentional cues prior to delivering treatment doses during conversational recast treatment may detract from the child’s attention to the relevant linguistic input, and decrease learning. Caution is warranted about this conclusion due to the possibility of clinician bias, and because coding from videos resulted in varying numbers of usable data points per session and per child.
    • Visual Comfort in Transitional Spaces

      Araji, Mohamad Tarek; Chalfoun, Nader; Jeffery, R. Brooks; Jabbour, Ghassan (The University of Arizona., 2004)
      The study emphasizes changing light conditions in architectural spaces as a major factor on human eye adaptation, which represents a potential case for a visual shock. This visual shock is experienced when occupants encounter a sudden field of light whose intensity is above or below the limit of human eye adaptable range. To examine this condition, a new methodology is developed and outlined. It identifies the visual shock within transitional spaces and allows architects to investigate strategies that influence visual comfort. The physiological field of vision analysis is used to first critique, then to adjust, and finally to interpret scenes within transitional spaces. The methodology begins by using a 180° angle fish-eye lens camera to capture 3-D photographs along a selected pedestrian pathway. The photographs are overlaid by a “field of view” diagram to deduct areas obstructed by human facial features (eyebrows, cheeks, and nose). Area weighted percentages of the net view profile is then calculated using an overlay hemispherical radial grid. These percentages represent the cut-off vision (0%), the one-eye vision (12.5%), the peripheral vision (25%), and the central vision (50%). Image metamorphosis is done by the aid of the Adobe Photoshop software to restrict the image to four monochromatic contrasts of shade. Parallel to photographs, actual light intensity readings are collected and calibrated to each assigned contrast on the images. To illustrate the methodology, a case of a person experiencing an extreme discomfort by walking in the direction of a blinding sunlight source has been chosen and investigated. 3-D Computer modeling is then adopted to investigate the different architectural daylight solutions as suggested by the modified design and predicts a visual comfort. This method provides a successful tool for investigating light in transitional spaces as well as contributes to enhancing pedestrian awareness of their surrounding environment and clarity of visual information.
    • Visual interpretation of vegetation classes from airborne videography: An evaluation of observer proficiency with minimal training

      McPherson, Guy R.; Drake, Samuel Edward, 1960- (The University of Arizona., 1993)
      This study evaluated the ability of individual subjects and small groups to correctly identify Arizona plant communities from color airvideo footage, explored the relationship of five background variables to subjects' success, and determined which community types were easiest and most difficult for subjects to identify. Forty-six volunteers from the University of Arizona School of Renewable Natural Resources participated in a multiple-choice pretest-posttest experiment using 30 different plant communities depicted in one-minute segments of videotape. Three hours of training increased mean individual score from 7 correct (pretest) to 21 correct (posttest), and mean group score from 11 to 24. All respondents significantly improved their performance, regardless of background. Posttest results showed no significant difference in ability among individuals or between individuals and groups. The most difficult community to identify was creosote-tarbush desertscrub; the easiest was paloverde-saguaro desertscrub. Findings support the feasibility of video interpretation by minimally-trained personnel.
    • The visual motor Gestalt test as a measure of intelligence and personality variation

      Gaylord, Helen Cook, 1915- (The University of Arizona., 1955)
    • Visual purple: A context for cultural understanding through the visual arts

      Parezo, Nancy; Leaman, Bethany Marie (The University of Arizona., 1994)
      Visual Purple is based on the author's experience with the Old Pasqua Youth Artists (OPYA) which is a biweekly, after-school program for Yaqui youth ranging from five to fifteen years of age. The paper seeks to relate the primary experiences of seeing and drawing linking them to cultural concepts, socialization patterns, and community setting. The Yaqui children's perceptual understanding acquired through learning and development co-varies with their cultural environment and upbringing. Through a content analysis of the OPYA artwork with special attention paid to the children's interactions, she contends that this understanding manifests as a set of aesthetic principles, the knowledge of core cultural symbols, and shared interpersonal behaviors based on cooperation, watching, and learning. The data suggests that the rich symbolism of Yaqui culture aesthetically socializes the children giving them an eye for detail and the ability to pick up and readily relay visual concepts.
    • Visual Quality Metrics Resulting from Dynamic Corneal Tear Film Topography

      Greivenkamp, John; Solem, Cameron Cole; Greivenkamp, John; Schwiegerling, Jim; Liang, Rongguang (The University of Arizona., 2017)
      The visual quality effects from the dynamic behavior of the tear film have been determined through measurements acquired with a high resolution Twyman-Green interferometer. The base shape of the eye has been removed to isolate the aberrations induced by the tear film. The measured tear film was then combined with a typical human eye model to simulate visual performance. Fourier theory has been implemented to calculate the incoherent point spread function, the modulation transfer function, and the subjective quality factor for this system. Analysis software has been developed for ease of automation for large data sets, and outputs movies have been made that display these visual quality metrics alongside the tear film. Post processing software was written to identify and eliminate bad frames. As a whole, this software creates the potential for increased intuition about the connection between blinks, tear film dynamics and visual quality.
    • Visualization of the flow of fluid within a centrifugal pump

      Linka, James Edward, 1929- (The University of Arizona., 1965)