Physical Sciences and Mathematics Commons^™

Neutron Interferometry Using A Single Modulated Phase Grating, Ivan J. Hidrovo Giler

LSU Master's Theses

Neutron grating interferometry provides information on phase and small-angle scatter in addition to attenuation. Previously, phase grating moiré interferometers (PGMI) with two or three phase gratings have been developed. These phase-grating systems use the moiré far-field technique to avoid the need for high-aspect absorption gratings used in Talbot-Lau interferometers (TLI) which reduce the neutron flux reaching the detector. We demonstrate through simulations a novel phase grating interferometer system for cold neutrons that requires a single modulated phase grating (MPG) for phase-contrast imaging, as opposed to the two or three phase gratings in previously employed PGMI systems. We compare the MPG …

A Data Repository For Clarifying Water Clarity: A Call To Use Metrics Best Suited To Corresponding Research And Management Goals In Aquatic Ecosystems (York River Estuary Case Study Dataset), Jessica S. Turner, Kelsey A. Fall, Carl T. Friedrichs

Data

This data repository is a permanent archive of the results presented in the associated publication (Turner et al. 2022, Limnology & Oceanography Letters, doi.xxxx). The objective of this study was to illustrate a water clarity phenomenon in the lower York River Estuary of the Chesapeake Bay. The data include light attenuation, Secchi depth, turbidity, and salinity from the lower York River Estuary in western Chesapeake Bay, Virginia, USA from the years 2014-2016.

A Data Repository For Effects Of Reduced Shoreline Erosion On Chesapeake Bay Water Clarity, Jessica Turner, Pierre St-Laurent, Marjorie A.M. Friedrichs, Carl T. Friedrichs

Data

This data repository is a permanent archive of the results presented in the associated publication (Turner et al. 2020, Science of the Total Environment, doi: 10.1016/j.scitotenv.2021.145157).

The objective of this study was to investigate the effects of shoreline erosion on water clarity in the Chesapeake Bay. To this end, we used the Chesapeake Bay ROMS Estuarine Carbon and Biogeochemistry (ChesROMS-ECB), a biogeochemical model embedded in the Regional Ocean Modeling System (ROMS). Using this model, we simulated a Chesapeake Bay estuary from 2001-2005 with varying magnitudes of sediment inputs from shoreline erosion and varying seabed erodibility conditions. Model results were compared …

Antenna Model In Simulation Of Spacecraft, Ti Zhou, Miao Yi, Sun Jun

Journal of System Simulation

Abstract: To give a solution how to catch relay satellite by spacecraft in the simulation system of manned craft, several 2D craft models were studied in the simulation software based on HLA, and some sufficient and necessary conditions and the methods were given to compute the visibility of relay satellite according to these models. On these methods, 3D antenna model and the orbit and attitude model of spacecraft were researched, and 3D antenna model was given with attitude information of craft. Finally, matrix translations were used to translate some vectors to the same reference frame, and the visibility was decided …

Application Of Haze Forecasts Based On Combined Multivariable And Probability Stepwise Regression, Yonghua Xie, Le Yang, Mingmin Zhang, Hengde Zhang

Journal of System Simulation

Abstract: Aiming at the less models available and poor prediction performance of current haze forecasting, combining statistical forecast and numerical prediction, a new haze prediction model was proposed based on hybrid stepwise multivariable and probability regression. Multivariable stepwise regression was used to control physical factors which influenced depending variable and the equation for atmosphere visibility wasgenerated. A haze prediction model based on binary variables was established using probability regression combined with factors like visibility and relative humidity. Experimental results have proved that compared with the existing CUACE, which is one of the main digital haze forecasting system, the accuracy using …

Studies On Kernels Of Simple Polygons, Jason Mark

UNLV Theses, Dissertations, Professional Papers, and Capstones

The kernel of a simple polygon is the set of points in its interior from which all points inside the polygon are visible. We formally establish that for a given convex polygon Q we can always construct a larger simple polygon with many reflex vertices such that Q is the kernel of P. We present algorithms for decomposing a strongly monotone polygon into star-polygons. This decomposition is applied for developing an efficient algorithm for placing a small number of vertical towers to cover the entire given 1.5D terrain. We also present an experimental investigation of the proposed algorithm. The implementation …

Approximation Algorithms For Illuminating 1.5d Terrain, Jiwan Khatiwada

UNLV Theses, Dissertations, Professional Papers, and Capstones

We review important algorithmic results for the coverage of 1.5D terrain by point guards. Finding the minimum number of point guards for covering 1.5D terrain is known to be NP-hard. We propose two approximation algorithms for covering 1.5D terrain by a fewer number of point guards. The first algorithm (Greedy Ranking Algorithm) is based on ranking vertices in term of number of visible edges from them. The second algorithm (Greedy Forward Marching Algorithm) works in greedy manner by scanning the terrain from left to right. Both algorithms are implemented in Python 2.7 programming language.

Nature, Identity, And Pastoralism: Changing Landscapes And Shifting Paradigms In The Mongolian Taiga, Jessica Vinson

Theses and Dissertations

The traditional environment of pastoralism is under assault from land degradation, rangeland conservation, and development paradigms that alter the everyday lives of Tsataan Dukha reindeer herders in the Mongolian taiga. This paper seeks to analyze the ways in which identity is shaped through experiences of or relationships with particular nonhuman places and beings, and how the Tsataan Dukha renegotiate their individual and collective identities with changing local landscapes that exert considerable pressures upon the social, political, and economic organization of Dukha life. Senses of place and of space are intimately tied to a sense of self, so disruption in environmental …

Application Of Multiple-Stepwise And Kalman Filtering In Haze Forecast, Yunhao Xian, Hengde Zhang, Yonghua Xie, Le Yang

Journal of System Simulation

Abstract: Considering the importance of objective haze forecast and the low accuracy rate of haze forecast, a new haze objective forecast correction method based on the multiple stepwise regression algorithms and the Kalman filtering algorithm is proposed. The multiple stepwise regression method is used to control the physical factor of the dependent variable, and the visibility forecast equation is established. The Kalman filtering method is adopted to correct the regression coefficient in multivariate stepwise regression algorithm according to the actual data, and the haze objective forecast correction model is established. The experiments are carried out in Beijing, Guangzhou, Nanjing and …

S-Visibility Problem In Vlsi Chip Design, Marzieh Eskandari, Mahdieh Yeganeh

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new version of very large scale integration (VLSI) layouts compaction problem is considered. Bar visibility graph (BVG) is a simple geometric model for VLSI chip design and layout problems. In all previous works, vertical bars or other chip components in the plane model gates, as well as edges, are modeled by horizontal visibilities between bars. In this study, for a given set of vertical bars, the edges can be modeled with orthogonal paths known as staircases. Therefore, we consider a new version of bar visibility graphs (BsVG). We then present an algorithm to solve the s-visibility …

Algorithms For Monotone Paths With Visibility Properties, Bikash Lama Bamjan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Constructing collision-free paths in Euclidean space is a well-known problem in computational geometry having applications in many fields that include robotics, VLSI, and covert surveillance. In this thesis, we investigate the development of efficient algorithms for constructing a collision-free path that satisfies directional and visibility constraints. We present algorithms for constructing monotone collision-free paths that tend to maximize the visibility of the boundary of obstacles. We also present implementation of some monotone path planning algorithms in Java Programming Language.

Remote Sensing Of Surface Visibility From Space: A Look At The United States East Coast, Amy L. Kessner

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

While important for the management of air quality, human health and transportation, surface visibility data currently are only available through ground-based measurements, such as the Automated Surface Observing System (ASOS), and therefore lack spatial coverage. In analogy to the recent work of using satellite-based aerosol optical depth (AOD) to derive surface dry aerosol mass concentration at continental-to-global scale for cloud-free conditions, this study evaluates the potential of AOD retrieved from the MODerate Resolution Imaging Spectroradiometer (MODIS) for deriving surface visibility. For this purpose of evaluation, the truncated and discrete visibility data from daily weather reports are not suitable and the …

Modeling Visibility In The El Paso Del Norte (Pdn) Region, Richard Medina Calderon

Open Access Theses & Dissertations

Poor visibility is a subject of growing public concern throughout the U.S, and an active area of research. Its societal impacts on air quality, aviation transport and traffic are significant. Aerosols play a fundamental role in the attenuation of solar radiation, and also affect visibility. The scattering and extinction coefficients of aerosol particles in the Paso del Norte Region have been calculated using the T- matrix model in conjunction with a laser particle counter. Inter-comparison of the model's results of the scattering and absorption coefficients against the corresponding data from a Photoacustic extinctiometer instrument (which measures in-situ absorption and scattering …

Towards A Conceptual Model Of User Acceptance Of Location-Based Emergency Services, Anas Aloudat, Katina Michael

Professor Katina Michael

This paper investigates the introduction of location-based services by government as part of an all-hazards approach to modern emergency management solutions. Its main contribution is in exploring the determinants of an individual’s acceptance or rejection of location services. The authors put forward a conceptual model to better predict why an individual would accept or reject such services, especially with respect to emergencies. While it may be posited by government agencies that individuals would unanimously wish to accept life-saving and life-sustaining location services for their well-being, this view remains untested. The theorised determinants include: visibility of the service solution, perceived service …

Slides: The Peril Of Energy Usage, Mike Tupper

The Promise and Peril of Oil Shale Development (February 5)

Presenter: Mike Tupper, Executive Vice President, Composite Technology Development, Inc.

9 slides

Overcoming Visibility Issues In A Small-To-Medium Retailer Using Automatic Identification And Data Capture Technology: An Evolutionary Approach, Dane Hamilton, K. Michael, Samuel F. Wamba

Professor Katina Michael

The aim of this paper is to review the inventory control practices of a small-to-medium retailer, in order to identify common challenges these organizations experience with respect to automated data capture (ADC) and the implementation of an enterprise wide information system. The study explores a single case of a hardware store in a regional town of NSW, Australia. Four semi-structured interviews were conducted with employees of a small-to-medium retailer focusing on issues related to inventory control including: delivery discrepancies, the checking and sorting of orders, locating stock and goods, loss prevention, customer purchasing and point of sale processing and replenishment. …

A See-Ability Metric To Improve Mini Unmanned Aerial Vehicle Operator Awareness Using Video Georegistered To Terrain Models, Cameron Howard Engh

Theses and Dissertations

Search and rescue operations conducted in wilderness environments can be greatly aided by the use of video filmed from mini-UAVs. While lightweight, inexpensive and easily transportable, these small aircraft suffer from wind buffeting and may produce video that is difficult to search. To aid in the video search process, we have created a system to project video frames into a 3D representation of the search region. This projection allows us to tie each frame of video to a real-world location, enabling a myriad of novel views, mosaics and metrics that can be used to guide the search including a new …

Evaluating The Usability Impacts Of Security Interface Adjustments In Word 2007, M Helala, S M. Furnell, M Papadaki

Australian Information Security Management Conference

Prior research has suggested that integrating security features with user goals and increasing their visibility would improve the usability of the associated functionalities. This paper investigates how these approaches affect the efficiency of use and the level of user satisfaction. The user interface of Word 2007 was modified according to these principles, with usability tests being conducted with both the original and the modified user interfaces. The results suggest that integrating security features with user goals improves the efficiency of use, but the impacts upon user satisfaction cannot be clearly identified based on the collected data. No indications of any …

Day 3: Friday, August 6, 2004: Air Quality And Energy Resources, University Of Colorado Boulder. Natural Resources Law Center

Energy Field Tour 2004 (August 4-6)

2 pages (includes illustration).

Slides: Lessons From The Pinedale Anticline Adaptive Management Process, Peter Aengst

Best Management Practices and Adaptive Management in Oil and Gas Development (May 12-13)

Presenter: Peter Aengst, Regional Associate, The Wilderness Society, Northern Rockies Office

24 slides

A Statistically-Based Method For Predicting Fog And Stratus Dissipation, Louis L. Lussier Iii

Theses and Dissertations

The method is a success in producing forecasts for ceiling and visibility criteria that had never previously been examined. It is suggested that the 15 OWS incorporate this methodology into their operational forecasting routine. Ceiling forecasts at Dover AFB and McGuire AFB show improvements over conditional climatology ranging from 1-51% with an average improvement of 19.2% when verified against an independent data set. McGuire AFB visibility forecasts show an average improvement over conditional climatology of 3%. These findings are of particular importance to the Air Force in general and specifically to the 15th Operational Weather Squadron (15 OWS) who produces …

Horizon Occlusion Culling For Real-Time Rendering Of Hierarchical Terrains, Parris K. Egbert, Brandon Lloyd

Faculty Publications

We present a technique to perform occlusion culling for hierarchical terrains at run-time. The algorithm is simple to implement and requires minimal pre-processing and additional storage, yet leads to 2-4 times improvement in framerate for views with high degrees of occlusion. Our method is based on the well-known occlusion horizon algorithm. We show how to adapt the algorithm for use with hierarchical terrains. The occlusion horizon is constructed as the terrain is traversed in an approximate front to back ordering. Regions of the terrain are compared to the horizon to determine when they are completely occluded from the viewpoint. Culling …

Agenda: Air Quality Protection In The West, University Of Colorado Boulder. Natural Resources Law Center

Air Quality Protection in the West (November 27-28)

Conference organizers, session moderators and/or speakers included University of Colorado School of Law professor Mark S. Squillace.

Visibility, acid rain, air toxics, and urban air pollution are the topics of an upcoming Center conference on air quality in the West. The conference will be held at the School of Law in Boulder on November 27-28, 1989. Presentations will describe the nature and scope of the issues, the existing legal framework and experience with its implementation, and proposed changes in the law. Emphasis will be placed on air quality issues in the West and efforts underway to address these problems. Special …

A Study Of Vertical And Horizontal Visibility Relationships Under Water, Jean J. Mccarthy

Journal of the Minnesota Academy of Science

A threefold study was undertaken to:

1) determine the nature of the mathematical relationship between vertical and horizontal visibility underwater

2) examine the feasibility of using the Secchi disc method to measure horizontal visibility in the photic zone;

3) obtain descriptive data on vertical and horizontal visibility in selected lakes of southern Minnesota.

The Secchi disc technique for measuring· visibility was modified to accommodate horizontal readings, and data were col1lected from 12 lakes at 5, 15 and 25 feet depths under controlled conditions. Reliability correlations were significant (p ( .01) and ranged from .764 to .994. Correlations and regression equations …