The Interaction Between Shock Waves and Solid Spheres Arrays in a Shock Tube

When a shock wave interacts with a group of solid spheres, non-linear aerodynamic behaviors come into effect. The complicated wave reflections such as the Mach reflection occur in. the wave propagation process. The wave interactions with vortices behind each sphere's wake cause fluctuation in the pressure profiles of shock waves. This paper reports an experimental study for the aerodynamic processes involved in the interaction between shock waves and solid spheres. A schlieren photography was applied to visualize the various shock waves passing through solid spheres. Pressure measurements were performed along different downstream positions. The experiments were conducted in both rectangular and circular shock tubes. The data with respect to the effect of the sphere array, size, interval distance, incident Mach number, etc., on the shock wave attenuation were obtained.

Aplicación de parámetros matemáticos en un trabajo multidisciplinario de composición musical asistida por computadora sobre una temática folklórica

Resumen: En el marco de un proyecto de la Vicerrectoría de Investigaciones de la Universidad de Caldas denominado “Resignificación músico-pictórica del mito de la Salamanca” surgió la conveniencia de aplicar y diseñar programas de fundamentación matemática que permitieran definir la estructura y el tratamiento acústico de la obra especialmente escrita para este proyecto. Principalmente nos basamos en la implementación de la Transformada Rápida de Fourier (Fast Fourier Transform) para el análisis de espectros armónicos y su modificación en vivo y en la utilización de un entorno de programación para procesamiento de sonido en tiempo real. El marco general de la investigación parte del enfoque de Regionalismo Crítico procedente de las propuestas de Kenneth Frampton referentes originalmente a la crítica de la arquitectura. El planteamiento como investigación mutidisciplinaria implica (1) una visión crítica de la substancia mítica y social subyacente, (2) una resignificación pictórica por medio de fotografía, animación y pintura, basada en la sustancia visual que contiene el mito, (3) un enfoque musical electroacústico, a partir del material que surge del folklor local, utilizando la intervención de instrumentos en vivo y procesamiento en tiempo real.

Isabel II y la fotografía : imágenes de una vida

Resumen: La adquisición de nuevos retratos de la reina Isabel II ha propiciado la revisión y puesta al día de un sugestivo corpus fotográfi co enormemente ilustrativo de la diversidad de recursos que la fotografía decimonónica ofrecía, así como de los cambios que afectaron al tema de la representación regia.

Ballistic impact of ceramics

The impact behaviour of a range of glass and ceramic materials has been studied using high-speed photography. A gas gun was used to project hardened spheres at plate specimens in the velocity range 30 to 1000m s-1. The target materials included soda-lime glass, boron carbide and various glass ceramics and aluminas. The performance of a particular ceramic was found to depend on a combination of parameters but of key importance was the relative hardness of the projectile and target materials. The fracture toughness, K(IC), had only a secondary effect.

Methodological keys for the acquisition and long-term use of photographic collections representing elements of Heritage

Contributed to: Fusion of Cultures. XXXVIII Annual Conference on Computer Applications and Quantitative Methods in Archaeology – CAA2010 (Granada, Spain, Apr 6-9, 2010)

Mapping and Distribution of Torpedograss and Evaluating the Effectiveness of Torpedograss Management Activities in Lake Okeechobee, Florida

Thousands of hectares of native plants and shallow open water habitat have been displaced in Lake Okeechobee’s marsh by the invasive exotic species torpedograss ( Panicum repens L.). The rate of torpedograss expansion, it’s areal distribution and the efficacy of herbicide treatments used to control torpedograss in the lake’s marsh were quantified using aerial color infra red (IR) photography.(PDF has 6 pages.)

Light Reflectance Characteristics and Remote Sensing of Waterlettuce

Waterlettuce ( Pistia stratiotes L.) is a free-floating exotic aquatic weed that often invades and clogs waterways in the southeastern United States. A study was conducted to evaluate the potential of using remote sensing technology to distinguish infestations of waterlettuce in Texas waterways. Field reflectance measurements showed that waterlettuce had higher visible green reflectance than associated plant species. Waterlettuce could be detected in both aerial color- infrared (CIR) photography and videography where it had light pink to pinkish-white image tonal responses. Computer analysis of CIR photographic and videographic images had overall accuracy assessments of 86% and 84%, respectively. (PDF contains 6 pages.)

An Experimental Study on Flame Propagation in Cornstarch Dust Clouds

Following the quantitative determination of dust cloud parameters, this study investigates the flame propagation through cornstarch dust clouds in a vertical duct of 780 mm height and 160 x 160 mm square cross section, and gives particular attention to the effect of small scale turbulence and small turbulence intensity on flame characteristics. Dust suspensions in air were produced using an improved apparatus ensuring more uniform distribution and repeatable dust concentrations in the testing duct. The dispersion-induced turbulence was measured by means of a particle image velocimetry (PIV) system, and dust concentrations were estimated by direct weighing method. This quantitative assessment made it possible to correlate observed flame behaviors with the parameters of the dust cloud. Upward propagating dust flames, from both closed/open bottom end to open/closed top end of the duct, were visualized by direct light and shadow photography. From the observation of propagation regimes and the measurements of flame velocity, a critical value of the turbulence intensity can be specified below which laminar flame propagation would be established. This transition condition was determined to be 10 cm/s. Laminar flames propagated with oscillations from the closed bottom end to the open top end of the testing duct, while the turbulent flames accelerated continuously. Both laminar and turbulent flames propagated with steady velocity from the open bottom end to the closed top end of the duct. The measured propagation velocity of laminar flames appeared to be in the range of 0.45-0.56 m/s, and it was consistent with the measurements reported in the literature. In the present experimental study, the influence of dust concentration on flame propagation was also examined, and the flame propagation velocity was found weakly sensitive to the variations in dust concentration. Some information on the flame structure was revealed from the shadow records, showing the typical heterogeneous feature of the dust combustion process.

Atomization Experiment of Pulsed Supersonic Liquid Jets

This paper will introduce an atomization experiment of pulsed supersonic water jets and polymer polyacrylamide (PAA) (0.1% and 1.0% weight density) solution jets. The jets are generated from a small high-speed liquid jet apparatus. The schlieren photography is applied to visualize the jets. The velocities of the jets are measured by cutting two laser beams. The effects of the nozzle diameter and the standoff distance on atomization and the jet velocity have been examined. The experiment shows that the polymer solution jets are easier to be atomized than water jets. This may be due to low surface tension of the polymer solution. The nozzle diameter causes different shock structures around the supersonic jets.

An Experimental Study of Kerosene Combustion in a Supersonic Model Combustor Using Effervescent Atomization

Investigation of kerosene combustion in a Mach 2.5 flow was carried out using a model supersonic combustor with cross-section area of 51 mm?70 mm, with special emphases on the characterization of effervescent atomization and the flameholdering mechanism using different integrated fuel injector/flameholder cavity modules. Direct photography, Schlieren imaging, and Planar Laser Induced Fluorescence (PLIF) imaging of OH were utilized to examine the cavity characteristics and spray structure, with and without gas barbotage. Schlieren images illustrate the effectiveness of gas barbotage in facilitating atomization and the importance of secondary atomization when kerosene sprays interacting with a supersonic crossflow. OH-PLIF images further substantiate our previous finding that there exists a local high temperature radical pool within the cavity flameholder and this radical pool plays a crucial role in promoting kerosene combustion in a supersonic combustor. The present results also demonstrate that the cavity characteristics can be different in non-reacting and reacting supersonic flows. As such, the conventional definition of cavity characteristics based on non-reacting flows needs to be revised.

Performance of a small high-speed liquid jet apparatus

The performance of a small high-speed liquid jet apparatus is described. Water jets of 200m/s to 700m/s have been obtained by firing a deformable lead slug from an air rifle into a stainless steel nozzle containing water sealed with a rubber diaphragm. Nozzle devices of using the impact extrusion (IE) method and cumulation (CU) method are designed to generate jets. The injection sequences are visualized using schlieren photography. The difference between the IE and CU methods in the jet generation is found.

Coral Remote Sensing Workshop: Proceedings and Recommendations, 17-18 September, Sheraton, Brickell Ave, Miami FL

Coral reefs exist in warm, clear, and relatively shallow marine waters worldwide. These complex assemblages of marine organisms are unique, in that they support highly diverse, luxuriant, and essentially self-sustaining ecosystems in otherwise nutrient-poor and unproductive waters. Coral reefs are highly valued for their great beauty and for their contribution to marine productivity. Coral reefs are favorite destinations for recreational diving and snorkeling, as well as commercial and recreational fishing activities. The Florida Keys reef tract draws an estimated 2 million tourists each year, contributing nearly $800 million to the economy. However, these reef systems represent a very delicate ecological balance, and can be easily damaged and degraded by direct or indirect human contact. Indirect impacts from human activity occurs in a number of different forms, including runoff of sediments, nutrients, and other pollutants associated with forest harvesting, agricultural practices, urbanization, coastal construction, and industrial activities. Direct impacts occur through overfishing and other destructive fishing practices, mining of corals, and overuse of many reef areas, including damage from souvenir collection, boat anchoring, and diver contact. In order to protect and manage coral reefs within U.S. territorial waters, the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce has been directed to establish and maintain a system of national marine sanctuaries and reserves, and to monitor the condition of corals and other marine organisms within these areas. To help carry out this mandate the NOAA Coastal Services Center convened a workshop in September, 1996, to identify current and emerging sensor technologies, including satellite, airborne, and underwater systems with potential application for detecting and monitoring corals. For reef systems occurring within depths of 10 meters or less (Figure 1), mapping location and monitoring the condition of corals can be accomplished through use of aerial photography combined with diver surveys. However, corals can exist in depths greater than 90 meters (Figure 2), well below the limits of traditional optical imaging systems such as aerial or surface photography or videography. Although specialized scuba systems can allow diving to these depths, the thousands of square kilometers included within these management areas make diver surveys for deeper coral monitoring impractical. For these reasons, NOAA is investigating satellite and airborne sensor systems, as well as technologies which can facilitate the location, mapping, and monitoring of corals in deeper waters. The following systems were discussed as having potential application for detecting, mapping, and assessing the condition of corals. However, no single system is capable of accomplishing all three of these objectives under all depths and conditions within which corals exist. Systems were evaluated for their capabilities, including advantages and disadvantages, relative to their ability to detect and discriminate corals under a variety of conditions. (PDF contains 55 pages)

DADAISM Project Plan

The DADAISM project brings together researchers from the diverse fields of archaeology, human computer interaction, image processing, image search and retrieval, and text mining to create a rich interactive system to address the problems of researchers finding images relevant to their research. In the age of digital photography, thousands of images are taken of archaeological artefacts. These images could help archaeologists enormously in their tasks of classification and identification if they could be related to one another effectively. They would yield many new insights on a range of archaeological problems. However, these images are currently greatly underutilized for two key reasons. Firstly, the current paradigm for interaction with image collections is basic keyword search or, at best, simple faceted search. Secondly, even if these interactions are possible, the metadata related to the majority of images of archaeological artefacts is scarce in information relating to the content of the image and the nature of the artefact, and is time intensive to enter manually. DADAISM will transform the way in which archaeologists interact with online image collections. It will deploy user-centred design methodologies to create an interactive system that goes well beyond current systems for working with images, and will support archaeologists’ tasks of finding, organising, relating and labelling images as well as other relevant sources of information such as grey literature documents.

NOAA Coastal Change Analysis Program (C-CAP): Guidance for Regional Implementation

EXECUTIVE SUMMARY: The Coastal Change Analysis Programl (C-CAP) is developing a nationally standardized database on landcover and habitat change in the coastal regions of the United States. C-CAP is part of the Estuarine Habitat Program (EHP) of NOAA's Coastal Ocean Program (COP). C-CAP inventories coastal submersed habitats, wetland habitats, and adjacent uplands and monitors changes in these habitats on a one- to five-year cycle. This type of information and frequency of detection are required to improve scientific understanding of the linkages of coastal and submersed wetland habitats with adjacent uplands and with the distribution, abundance, and health of living marine resources. The monitoring cycle will vary according to the rate and magnitude of change in each geographic region. Satellite imagery (primarily Landsat Thematic Mapper), aerial photography, and field data are interpreted, classified, analyzed, and integrated with other digital data in a geographic information system (GIS). The resulting landcover change databases are disseminated in digital form for use by anyone wishing to conduct geographic analysis in the completed regions. C-CAP spatial information on coastal change will be input to EHP conceptual and predictive models to support coastal resource policy planning and analysis. CCAP products will include 1) spatially registered digital databases and images, 2) tabular summaries by state, county, and hydrologic unit, and 3) documentation. Aggregations to larger areas (representing habitats, wildlife refuges, or management districts) will be provided on a case-by-case basis. Ongoing C-CAP research will continue to explore techniques for remote determination of biomass, productivity, and functional status of wetlands and will evaluate new technologies (e.g. remote sensor systems, global positioning systems, image processing algorithms) as they become available. Selected hardcopy land-cover change maps will be produced at local (1:24,000) to regional scales (1:500,000) for distribution. Digital land-cover change data will be provided to users for the cost of reproduction. Much of the guidance contained in this document was developed through a series of professional workshops and interagency meetings that focused on a) coastal wetlands and uplands; b) coastal submersed habitat including aquatic beds; c) user needs; d) regional issues; e) classification schemes; f) change detection techniques; and g) data quality. Invited participants included technical and regional experts and representatives of key State and Federal organizations. Coastal habitat managers and researchers were given an opportunity for review and comment. This document summarizes C-CAP protocols and procedures that are to be used by scientists throughout the United States to develop consistent and reliable coastal change information for input to the C-CAP nationwide database. It also provides useful guidelines for contributors working on related projects. It is considered a working document subject to periodic review and revision.(PDF file contains 104 pages.)

Marine Debris Survey Manual

Over the last several years, concern has increased about the amount of man-made materials lost or discarded at sea and the potential impacts to the environment. The scope of the problem depends on the amounts and types of debris. One problem in making a regional comparison of debris is the lack of a standard methodology. The objective of this manual is to discuss designs and methodologies for assessment studies of marine debris. This manual has been written for managers, researchers, and others who are just entering this area of study and who seek guidance in designing marine debris surveys. Active researchers will be able to use this manual along with applicable references herein as a source for design improvement. To this end, the authors have synthesized their work and reviewed survey techniques that have been used in the past for assessing marine debris, such as sighting surveys, beach surveys, and trawl surveys, and have considered new methods (e.g., aerial photography). All techniques have been put into a general survey planning framework to assist in developing different marine debris surveys. (PDF file contains 100 pages.)