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Laser beam shaping techniques

Description: Industrial, military, medical, and research and development applications of lasers frequently require a beam with a specified irradiance distribution in some plane. A common requirement is a laser profile that is uniform over some cross-section. Such applications include laser/material processing, laser material interaction studies, fiber injection systems, optical data image processing, lithography, medical applications, and military applications. Laser beam shaping techniques can be divided into three areas: apertured beams, field mappers, and multi-aperture beam integrators. An uncertainty relation exists for laser beam shaping that puts constraints on system design. In this paper the authors review the basics of laser beam shaping and present applications and limitations of various techniques.
Date: March 16, 2000
Creator: Dicky, Fred M.; Weichman, Louis S. & Shagam, Richard N.
Partner: UNT Libraries Government Documents Department

Habitat '67

Description: The mold containing the steel armature is readied for concrete pour to create one of the 354 units needed for the construction of the housing complex.
Access: Restricted to UNT Community Members. Login required if off-campus.
Date: 1967
Creator: Safdie, Moshe
Partner: UNT College of Visual Arts + Design
open access

Shaping Appropriate Verbal Responses in a Social Situation With a Withdrawn Retarded Adolescent

Description: "Shaping" or "method of successive approximation" is a procedure which may be applied to increase the frequency of a response which has a low operant level, or it may also be used to bring about responses which have not been previously emitted. In "shaping," the experimenter initially reinforces a response which is within the behavorial repertoire of the subject. Then, the experimenter reinforces only responses which approximate the behavior which is desired. The final behavior is then directly reinforced.
Date: May 1973
Creator: Thompson, James N.
Partner: UNT Libraries
open access

Constructional Fear Treatment for Dogs in Shelters

Description: Of the approximately 3.9 million dogs that enter US animal shelters each year, many exhibit behaviors related to fear, which can affect their likelihood of adoption. Current dog training procedures to treat fear include counterconditioning and desensitization, which can often take months or years to show any behavior change and do not teach specific behaviors aimed to increase the dog's chance of being adopted. The current study used a negative reinforcement shaping procedure to teach fearful dogs to approach and and interact with people. The results showed that constructional fear treatment increased the amount of time the dog spent at the front of the kennel, and increased sniffing, tail wagging, and accepting petting for all 3 participants.
Date: August 2016
Creator: Katz, Morgan
Partner: UNT Libraries
open access

The Effects of Capturing and Searching on the Acquisition of a Simple Arm Position

Description: The present experiment compared two methods of training a simple arm position using auditory feedback: capture and search. The participants were four right-handed female college students. During capture, auditory feedback was delivered by the experimenter after the participant moved along a single axis into the target position. During search, auditory feedback was produced by the computer after the participant left clicked a mouse inside the target location. The results of a multi-element design showed that participants performed more accurately during capture training than search training. Pre-training and post-training probes, during which no auditory feedback was provided, showed similar fluctuations in accuracy across probe types. A retention check, performed seven days after the final training session, showed higher accuracy scores for search than capture, across all four participants. These findings suggest that TAGteach should incorporate an approach similar to search training to improve training outcomes.
Date: August 2011
Creator: Heth, Travis R.
Partner: UNT Libraries
open access

Second order Pseudo-gaussian shaper

Description: The purpose of this document is to provide a calculus spreadsheet for the design of second-order pseudo-gaussian shapers. A very interesting reference is given by C.H. Mosher ''Pseudo-Gaussian Transfer Functions with Superlative Recovery'', IEEE TNS Volume 23, p. 226-228 (1976). Fred Goulding and Don Landis have studied the structure of those filters and their implementation and this document will outline the calculation leading to the relation between the coefficients of the filter. The general equation of the second order pseudo-gaussian filter is: f(t) = P{sub 0} {center_dot} e{sup -3kt} {center_dot} sin{sup 2}(kt). The parameter k is a normalization factor.
Date: November 22, 2002
Creator: Beche, Jean-Francois
Partner: UNT Libraries Government Documents Department
open access

Low-speckle holographic beam shaping of high-coherence EUV sources

Description: This paper describes a method to arbitrarily shape and homogenize high-coherence extreme ultraviolet sources using time-varying holographic optical elements and a scanning subsystem to mitigate speckle. In systems with integration times longer than 100 ms, a speckle contrast below 1% can be achieved.
Date: August 1, 2010
Creator: Anderson, Christopher N.; Miyakawa, Ryan H. & Naulleau, Patrick
Partner: UNT Libraries Government Documents Department
open access

A Shaping Procedure for Introducing Horses to Clipping

Description: The purpose of the current study is to evaluate a procedure that can be used to introduce horses to clipping. Negative reinforcement was used in a shaping paradigm. Shaping steps were conducted by the handler, starting with touching the horse with the hand, then touching the horse with the clippers while they are off, culminating with touching the horse with the clippers while they are on. When a horse broke contact with either the hand or the clippers, the hand or the clippers were held at that point until the horse emitted an appropriate response. When the horse emitted an appropriate response, the clippers were removed, and the handler stepped away from the horse. For all eight horses, this shaping plan was effective in enabling the clipping of each horse with minimal inappropriate behavior and without additional restraint. The entire process took under an hour for each horse.
Date: December 2019
Creator: Hardaway, Alison K
Partner: UNT Libraries
open access

Investigating the Effects of Teaching on Response Allocation by Implementing a Changing Criterion Procedure

Description: The study of choice and allocation has often focused on certain parameters of reinforcement, but rarely on historical variables. The goal of this study was to investigate the potential effects of gradual vs. abrupt teaching methods on future response allocation. A secondary goal was to see if the results of teaching-method manipulations might be correlated with the parameters that the teaching method produced, specifically unit costs, rate of reinforcement, or error rates. Results indicate that these teaching procedures can produce transient shifts in allocation, but not in a consistent direction. Neither unit cost nor rate or reinforcement alone can account for observed response allocation shifts after training. Researchers saw that subjects reliably shifted towards a manipulanda that produced higher rates of errors, therefore investigating the influence that error rate (or types of errors) may have on response allocation may aid in general teaching method preferences. Future research could focus on the combination of historical procedural variables and current variables that could determine response allocation.
Date: August 2022
Creator: Krilcich, Rachel AnnaSoo
Partner: UNT Libraries
open access

Equines Do Not Live for Grass Alone: Teaching Equines with Social Interaction

Description: Most horse training methods heavily rely on negative reinforcement and punishment. However, there is a movement in the horse community to utilize positive reinforcement to meet training goals. Although food has been used effective as a reinforcer with horses, social interaction has also been demonstrated to function as a positive reinforcer for animals. Utilizing social interaction as a reinforcer may lead to several benefits for both the trainer and animal. Some of the benefits can be improved relationships between animals and their caretakers and improved animal welfare. The purpose of this study was to apply Owens and Owens et al. previous research protocols to three equines to assess if social interaction, in the form of petting and gentle scratching, would function as a reinforcer. Using a changing criterion design, this study demonstrated that petting and gentle scratching could function as a reinforcer to teach three equines to stay and come in their natural environment.
Date: May 2020
Creator: Nishimuta, Maasa
Partner: UNT Libraries
open access

A Safe and Fast Deworming Procedure for Horses

Description: Most horse owners administer oral deworming medication to their horses on a set schedule, often six times per year. The deworming process involves using a plastic syringe to inject a thick paste into the horse's mouth. Most horse owners do not specifically train their horses to accept this procedure. Consequently, many horses resist the procedure and some horses engage in behaviors, such as head shaking, pulling away, or even rearing, that may be dangerous to humans or to themselves. This study used a negative reinforcement shaping procedure to train six horses to accept dewormer medication. The procedure consisted of a food sampling phase followed by three shaping phases that simulated the deworming task, first using only the experimenter's hand, then a small syringe, and finally a large syringe. Once the horse was acclimated to the syringe, the horse's preferred liquid food was delivered through the syringe at the end of each trial. By the end of the study, all participants successfully completed the procedure and were able to stand still with no or minimal head movements while being dewormed.
Date: May 2022
Creator: Ward, Jessica Lauren
Partner: UNT Libraries
open access

The Power of One Reinforcer

Description: Animal trainers use shaping to teach many behaviors. However, during shaping, the organism may engage in behaviors other than the target behavior or approximations to the target behavior. If the animal is engaged in other behaviors, the rate of reinforcement may decrease and the trainer may resort to what is sometimes referred to as a “desperation click.” That is, the trainer delivers one reinforcer for a behavior that is not a successive approximation to the target response. Anecdotal reports from trainers suggest that sometimes the animal continues to repeat this other behavior that received only one reinforcer, even in the absence of further reinforcement for that behavior. This study compared whether, during a one minute extinction period, participants spent more time engaged in a behavior that had been reinforced only once after a brief period of no reinforcement or in a behavior that had been reinforced multiple times. Participants, who were university students, played a tabletop game that involved touching and manipulating small objects. Five conditions were repeated twice for each participant: reinforcement for interacting with a training object alone, reinforcement for interacting with a training object with other objects present, reinforcement for interacting with a target object, one reinforcer for interacting with a third object immediately following a brief period of no reinforcement, and reinforcement for interacting with any object. Results from this study show that a desperation click situation can be reliably produced in a controlled setting. When participants received one reinforcer for interacting with a new object following a period of no reinforcement, they interacted with the new object for a longer or equal amount of time as compared to an object that had a history of reinforcement.
Date: August 2013
Creator: Hunter, Mary E.
Partner: UNT Libraries
open access

Teaching Children How to Stay Still Using Movies to Provide Continuous Feedback

Description: External beam radiation therapy is often used as a form of treatment for individuals diagnosed with cancer. However, because staying completely still can often be difficult for children, sedation is often used daily to remedy the need for stillness. In this document, we introduce the development, implementation, and testing of a technology designed to teach healthy children to self-monitor and control their movements. This technology monitored a child's body movement and created a continuous feedback loop, playing a preferred movie based on the amount of body movement observed. Study 1 compares the amount of body movement observed when children were instructed to remain still (instructions alone) to access to a movie contingent on maintained low rates of movement (contingent movie). Study 2 compares the amount of body movement observed in the instructions alone condition with two other conditions: non-contingent access to a movie (non-contingent movie) and contingent movie. Study 3 compares the amount of body movement observed in the instructions alone condition to the contingent movie condition over an extended period of time. Lastly, Study 4 compares the amount of body movement observed when children have previously been taught to stay still using the technology described above across various days throughout various conditions. Generally, we found three things: a) instructions alone were insufficient to produce the level of control over motion required; b) some control over motion was established in the non-contingent movie condition relative to the instructions alone condition; and c) the combination of movies and feedback contingent on movement was necessary to gain the level of control over body motion necessary to adhere to the medical protocol.
Date: December 2019
Creator: Otero, Maria Jose
Partner: UNT Libraries
open access

Cultivating Liberation within a Verbal Community: Evaluating the Effects of Collective Shaping on Written Narratives and Reflective Statements about Social Issues

Description: The purpose of this study was to evaluate the effects that a training workshop and collective shaping had on the reflective statements and feeling and emotion labels in a written response to videos relating to social issues. The workshop included a presentation interspersed with videos to help practice dialoguing and guide discussion toward generating discourse for social change. The effects of the workshop were evaluated using a single subject A – B design with multiple probe measures across three participants. Participants were given a prompt to write a descriptive narrative in response to a video clip, creating a permanent product for quantitative and qualitative analyses. The study resulted in slight increasing trends for both reflective statements and feeling and emotion labels for Participants 1 and 2. Further analyses show that Participant 3, despite showing little change across reflective statements and feeling and emotion labels, showed significant increase and more stability in the percentage of total words within reflective statements. The results of the workshop are discussed in the context of future research, including the role of social issues in our everyday language and how that affects us at a personal level.
Date: August 2020
Creator: Perez Glendon, Emily L
Partner: UNT Libraries
open access

An Alternative Form of Laser Beam Characterization

Description: Careful characterization of laser beams used in materials processing such as welding and drilling is necessary to obtain robust, reproducible processes and products. Recently, equipment and techniques have become available which make it possible to rapidly and conveniently characterize the size, shape, mode structure, beam quality (Mz), and intensity of a laser beam (incident power/unit area) as a function of distance along the beam path. This facilitates obtaining a desired focused spot size and also locating its position. However, for a given position along the beam axis, these devices typically measure where the beam intensity level has been reduced to I/ez of maximum intensity at that position to determine the beam size. While giving an intuitive indication of the beam shape since the maximum intensity of the beam varies greatly, the contour so determined is not an iso-contour of any parameter related to the beam intensity or power. In this work we shall discuss an alternative beam shape formulation where the same measured information is plotted as contour intervals of intensity.
Date: June 30, 2000
Creator: KNOROVSKY,GERALD A. & MACCALLUM,DANNY O.
Partner: UNT Libraries Government Documents Department
open access

Constant field gradient planar cavity structure

Description: A cavity structure is described having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam.
Date: December 1, 1997
Creator: Kang, Yoon W. & Kustom, R.L.
Partner: UNT Libraries Government Documents Department
open access

AN INVESTIGATION OF THE BEAM MONITOR FOR THE CLUSTER KLYSTRON.

Description: The cluster klystron project required a beam monitor to check the quality of the hollow beam shape. Since the power density of the beam is very large, a common phosphorescent screen doesn't work. We investigated varies types of monitors. The related problems were also discussed.
Date: August 21, 2001
Creator: ZHAO,Y.
Partner: UNT Libraries Government Documents Department
open access

On possible use of bent crystal to improve Tevatron beam scraping

Description: A possibility to improve the Tevatron beam halo scraping using a bent channeling crystal instead of a thin scattering primary collimator is studied. To evaluate the efficiency of the system, realistic simulations have been performed using the CATCH and STRUCT Monte Carlo codes. It is shown that the scraping efficiency can be increased and the accelerator-related backgrounds in the CDF and DØ collider detectors can be reduced by about one order of magnitude. Results on scraping efficiency versus thickness of amorphous layer of the crystal, crystal alignment and its length are presented.
Date: April 8, 1999
Creator: A.I. Drozhdin, N.V. Mokhov and V.M. Biryukov
Partner: UNT Libraries Government Documents Department
open access

Limitations of interaction-point spot-size tuning at the SLC

Description: At the Stanford Linear Collider (SLC), the interaction-point spot size is minimized by repeatedly correcting, for both beams, various low-order optical aberrations, such as dispersion, waist position or coupling. These corrections are performed about every 8 hours, by minimizing the IP spot size while exciting different orthogonal combinations of final-focus magnets. The spot size itself is determined by measuring the beam deflection angle as a function of the beam-beam separation. Additional information is derived from the energy loss due to beamstrahlung and from luminosity-related signals. In the 1996 SLC run, the typical corrections were so large as to imply a 20-40% average luminosity loss due to residual uncompensated or fluctuating tunable aberrations. In this paper, the authors explore the origin of these large tuning corrections and study possible mitigations for the next SLC run.
Date: May 1, 1997
Creator: Emma, P.; Hendrickson, L.J.; Zimmermann, F. & Raimondi, P.
Partner: UNT Libraries Government Documents Department
open access

The Function-Altering Effects of Contingency-Specifying Stimuli

Description: Three children between the ages of 3 and 3 1/2 were asked to choose a colored object from an array of 5 colors in a baseline condition. After color preferences were established, stickers, small toys and praise were made contingent on choosing the least preferred color. After the first experimental condition resulted in consistent choosing of the least preferred color, a second experimental condition was implemented. At the beginning of each session a contingency-specifying stimulus (CSS) was presented, each CSS specifying a different color to be selected. Both contingency-shaping and CSS presentation resulted in stimulus control over responding. However, CSS presentation resulted in immediate redistributions of behavioral units across CSS sessions.
Date: August 1992
Creator: Ford, Victoria L.
Partner: UNT Libraries
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