2,733 research outputs found
Satellite retrieved aerosol properties for battlespace characterization and sensor performance
No full textSea basing operations in coastal environments require a rapid and accurate description of the physical conditions in the region. Battlespace characterization and sensor performance assist in optimizing the efficiency and safety of operations, of which the detection of targets at low level above the sea surface is all-important. The environmental conditions of the marine boundary layer (MBL) – due to weather and atmospheric effects – change continuously in space and time, which certainly holds for the aerosol make-up. Models have been developed to describe the electrooptical propagation in the boundary layer as a function of meteorological parameters. EOSTAR is such an end-toend model suite for EO sensor performance in which the Advanced Navy Aerosol Model (ANAM) is embedded for computing the aerosol extinction. While ANAM provides favourable results in open ocean conditions, in coastal zones the model lacks accuracy due to the presence of aerosols from a variety of sources that need to be assessed. In offshore wind conditions continental aerosols of anthropogenic and natural origin mix with marine aerosols produced in the surf zone and by wave breaking further offshore. Radiometers on satellites can be used to retrieve the spatial variation over an extended area determined by the swath width, with a resolution determined by the radiometer pixel size. In this contribution we explore the potential of satellite measurements to provide information on the aerosol properties over the range of interest in order to correctly handle their influence on transmission characteristics in the coastal zone. Results from measurements of the multidisciplinary Maritime REA/Battlespace Preparation 2007 trial, held during 20 April and 5 May 2007 near the vicinity of the island Elba along the west coast of Italy, are presented in this analysis. For one particular day, the satellite retrieved aerosol optical thickness (AOT) is to be compared with hand-held sun photometer measurements for quality assessment. The AOT values are converted into aerosol extinction coefficients for a pre-defined path. For one visible wavelength channel the transmission loss is computed with these coefficients and is compared with the computed transmission loss for the path in case of a) a single extinction coefficient obtained from measurements and b) a modeled extinction coefficient obtained from ANAM
Evaluation tools for the effectiveness of Infrared Countermeasures and Signature reduction for Ships
No full textThe protection of ships against infrared guided missiles is a concern for modern naval forces. The vulnerability of ships can be reduced by applying countermeasures such as infrared decoys and infrared signature reduction. This paper will present a set of simulation tools which can be used for assessing the effectiveness of these measures. The toolset consists of a chain of models which calculate the infrared signature of a ship (EOSM), generate an infrared image of the ship in a realistic sea and sky background (EOSTAR) and determine the behaviour of an infrared missile seeker against these images and simulate the complete missile fly-out including countermeasure deployment (EWM). All model components will be briefly discussed. Typical simulation runs will be shown. © 2010 Copyright SPIE - The International Society for Optical Engineering
Intelligent route surveillance
No full textIntelligence on abnormal and suspicious behaviour along roads in operational domains is extremely valuable for countering the IED (Improvised Explosive Device) threat. Local sensor networks at strategic spots can gather data for continuous monitoring of daily vehicle activity. Unattended intelligent ground sensor networks use simple sensing nodes, e.g. seismic, magnetic, radar, or acoustic, or combinations of these in one housing. The nodes deliver rudimentary data at any time to be processed with software that filters out the required information. At TNO (Netherlands Organisation for Applied Scientific Research) research has started on how to equip a sensor network with data analysis software to determine whether behaviour is suspicious or not. Furthermore, the nodes should be expendable, if necessary, and be small in size such that they are hard to detect by adversaries. The network should be self-configuring and self-sustaining and should be reliable, efficient, and effective during operational tasks - especially route surveillance - as well as robust in time and space. If data from these networks are combined with data from other remote sensing devices (e.g. UAVs (Unmanned Aerial Vehicles)/aerostats), an even more accurate assessment of the tactical situation is possible. This paper shall focus on the concepts of operation towards a working intelligent route surveillance (IRS) research demonstrator network for monitoring suspicious behaviour in IED sensitive domains
R.M. Simmons presentation, Rena Smart book review
No full textR.M. Simmons of the Gospel Music Workshop of America gives a presentation on the African influence in the African American religious experience. He explains how African slaves brought to America their concept of music (utilitarian concept of music). Simmons further discusses the fusion between the utilitarian concept and the Western concept of religion resulting in spirituals. He also describes hymn categories in early forms of formal African American worship experiences. Simmons takes questions from the audience among which is Dr. Riggins Earl Jr. Video concludes with a book review on Christian Theology and Ethics by Rena Smart.The Atlanta University Center Robert W. Woodruff Library acknowledges the generous support of the National Endowment for Humanities - Humanities Collections and Reference Resources Implementation Project Grant in supporting the processing and digitization of a number of its major archival collections as part of the project: Spreading the Word: Expanding Access to African American Religious Archival Collections at the Atlanta University Center Robert W. Woodruff Library.</em
Towards a zero-emission naphtha cracking industry in the Netherlands: A model-based exploration of policy options to accelerate electrification
No full textFollowing the Paris Agreement, the national government of the Netherlands reached the Climate Agreement together with more than 100 organizations. As part of this agreement, the industry sector is faced with the ambitious goal of 59% CO2 reduction in 2030 with respect to 1990 levels. Since the naphtha cracking industry is one of the most emission-intensive industries worldwide, decarbonization of this industry can deliver a significant contribution to reaching the climate goals. Among other transformations, electrification is regarded as an important decarbonization strategy. However, electrification in the naphtha cracking industry currently faces several barriers. For an important part, these stem from fundamental uncertainties concerning the future markets, the availability of renewable electricity and the capacity of the electricity grid. Moreover, high investment costs combined with a lack of financial and fiscal incentives and low carbon prices make the business case for electrification currently unattractive. In addition, the high degree of systems integration onsite and the baseload nature of the cracking process make the implementation of electrification challenging. Government policy could play a pivotal role in resolving these barriers. The purpose of this research is therefore to explore policy options at a national level that enable an acceleration in the chemical industry’s electrification while being robust against uncertainty. For this purpose, the Robust Decision-Making (RDM) framework was applied. As part of this framework, a system dynamics (SD) model was built to describe the behavior of the socio-technical system of the naphtha cracking industry. This model was then subjected Exploratory Modelling & Analysis (EMA) to simulate the impact of various policy options on the electrification rate against a large number of plausible future scenarios. Moreover, a robust policy search was conducted using a multi-objective robust optimization algorithm.The analyses of the simulation results suggest that profound changes in current policy instruments are required to achieve a significant degree of electrification in the naphtha cracking industry with sufficient certainty. It is advised to increase government funding for electrification, implement a fiscal shift away from gas towards electricity and to increase the effective carbon levy imposed on the industry. However, though the analyses show that government policy has a significant impact on the development of electrification, its success appears conditional on external factors, most importantly, developments in the energy and carbon markets. In fact, the electricity price and the ETS carbon price turn out to be more influential on emission reduction than most policy interventions. The availability of renewable electricity is the single most influential factor affecting CO2 emissions and hence, is considered paramount in achieving emission reduction. Therefore, policy aimed at accelerating electrification should be accompanied by decisive government action regarding the development of renewable electricity sources.Engineering and Policy Analysi
Velocity-Gradient Probability Distribution Functions in a Lagrangian Model of Turbulence
No full textThe Recent Fluid Deformation Closure (RFDC) model of lagrangian turbulence is recast in path-integral language within the framework of the Martin-Siggia-Rose functional formalism. In order to derive analytical expressions for the velocity-gradient probability distribution functions (vgPDFs), we carry out noise renormalization in the low-frequency regime and find approximate extrema for the Martin-Siggia-Rose effective action. We verify, with the help of Monte Carlo simulations, that the vgPDFs so obtained yield a close description of the single-point statistical features implied by the original RFDC stochastic differential equations
Author Correction: Global geochemical fingerprinting of plume intensity suggests coupling with the supercontinent cycle
No full textThe original version of this Article omitted from the author list the 4th and 5th authors, Grant Cox and Ross Mitchell, who were both at Curtin University. Consequently, the corrected version of the Acknowledgements removes the following from the original version: ‘and Ross Mitchell’. In addition, the following was added to the Author Contributions: ‘G.M.C. and R.M. were involved in an early attempt of this study.’. This has been corrected in both the PDF and HTML versions of the Article
Colonising "The Coral Island": A Postcolonial Reading of R.M. Ballantyne's Children's "Classic"
No full textstudent essayBeing written during the rise of the British Empire in the 1850sm R.M. Ballantyne's boys' adventure story "The Coral Island" is in many ways a product of its time, conveying imperial ideas and Victorian values to the young reader. Through his portrayal of the native inhabitants in relation to his descriptions of the three British protagonists, the author creates a stereotyped image of the natives as primitive savages. Due to the further use of a first person narrator and realist pretensions, the dated racist ideas become influential upon the reader. In spite of the fact that the novel has been considered as an entertaining children's classic by generations since its first publication, "The Coral Island" should not be classified as good children's literature today but should rather be historicised as a result of its controversial contents. By adopting a postcolonial approach and applying postcolonial theory in my analysis of R.M. Ballantyne's "The Coral Island", I have in this essay endeavoured to demonstrate in what ways the novel would prove problematic as a children's book today. In my first chapter I present the imperial ideas and Victorian values that are conveyed, whereas in my second chapter I discuss Ballantyne's stereotyping of the natives. As a result of my study of this novel, I have exemplified how the author portrays the three British boys as representative of the Victorian ideals of the time. I have also illustrated their assumed superiority over nature and their roles as colonisers. Furthermore, my analysis of "The Coral Island" has revealed how Ballantyne communicates both white superiority as well as the Western "oblibation" to civilise primitive people throug Christian conversion. Consequently, the novel promotes the ideology of its time. As a result of my findings, I would like to argue that "The Coral Island" should today be viewed as a text conveying historical ideas and values rather than as an exciting children's classic
Accelerating MRO procedures for composite materials using innovative detection techniques
No full textThe development of large commercial aircraft such as the Airbus A350 and the Boeing 787, together with military aircraft such as the Lockheed Martin F35, with a large share of composite components of up to 50%, make it necessary for attention to be focussed on the development of new and effective maintenance strategies. In this paper, we address the development of ultrasonic measurement techniques, with a focus on structural health monitoring (SHM) techniques that are able to quickly inspect large structural parts of the aircraft. The combination of real-time SHM techniques, together with the parallel development of automated repair techniques for bonded structures, will make it possible to operate the aircraft at lower costs and for longer periods of time, thereby increasing the economic life of these aircraft structures.Aerospace Structures and MaterialsAerospace Engineerin
Aerosol optical depth over Europe -Retrieval from ATSR-2 data for the year 2000
No full textAerosol properties are retrieved from ATSR-2 data (ERS-2 satellite) by utilizing the dual view for application over land and the single view for application over water. These two algorithms have been merged into a fast and efficient algorithm that allows for near real-time processing and which is suitable for operational use. It includes corrections for surface and atmospheric effects including fully automated cloud screening procedures. The algorithm can be applied to retrieve aerosol optical depth (AOD), Ångström parameter and aerosol types. The application to data for the year 2000 over Europe is presented. The retrieved AOD over land compares favorably with collocated sun-photometer data from the Aerosol Robotic Network (AERONET)
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