Radar imaging

The article of record as published may be found at http://dx.doi.org/1088/0266-5611/29/5/050301Because of their ability to operate without regard to day, night or weather conditions, radar systems are ubiquitous in remote sensing operations and are used in a wide variety of commercial and military applications. High resolution radar imaging, however, is a remote sensing subcategory that requires raw radar data to be collected over an artificially extended aperture that is much larger than the radar receiving antenna and processed to create a reflectivity image of a scene (typically by backprojection methods). These synthetic aperture radar imaging (SAR) methods have been in use for over 50 years and, while the methodology for simple radar imaging is quite mature, there are still many active research programs seeking to extend the quality of—and information obtained from—SAR images

Microlocal ISAR for Low Signal-to-Noise Environments

The problem of extracting radar target information from multi-aspect high-range-resolution data is examined. We suggest a new non-imaging approach that is based on microlocal analysis, which is a mathematical theory developed to handle highfrequency asymptotics. In essence, we relate features of the target to high-frequency components of the data. To deal with realistic band-limited data, we propose an iterative algorithm (based on the generalized Radon-Hough transform) in which we estimate the high-frequency features of the data, one after another, and subtract out the corresponding band-limited components. The algorithm has been successfully tested on noisy data, and may have a number of advantages over conventional imaging methods.This work was supported by the Office of Naval Research. M.C. also thanks Gary Hewer and the ASEE Summer Faculty Research Program for supporting her stay at China Lake

Beauty and the Bridge

Over 65,000 vehicles per day use the US 20/US 31 interchange in South Bend. The bridge has suffered multiple truck hits due to low vertical clearance over US 31. Ciorba was tasked with designing options to improve the vertical clearance by over 1’. In conjunction with this objective, the city sought beautification enhancements to the structure. We will review the several renditions that were produced during the city’s search to fund the beautification

Contribution and Distribution Flexibility and Tax Pass-Through Entities

The way jurisdictions design their tax systems for business operations can be a contentious issue, as they try to balance the competing goals of raising sufficient tax revenue without unduly inhibiting commercial investment and activities. Such tax design can be of particular importance for small and medium enterprises, which due to their size, inherent characteristics, and resources can struggle with tax compliance. Those attributes can also make business tax regressive. A number of countries around the world have adopted business entities that utilise corporate characteristics, such as liability protection for members and separate legal entity status, but have the characteristic of tax pass-through, with members assessed directly on the income and losses of the entity. Examples include limited liability partnerships (LLPs) in the United Kingdom, look-through companies in New Zealand, and limited liability companies (LLCs) in the United States. In some jurisdictions, these tax pass-through entities have been extremely popular, which in part has been attributed to flexibility for the members in terms of governance and the facilitation of contributions and subsequent distributions. This flexibility is arguably a desired commercial feature of business entities. However, such flexibility with contributions and distributions is seen as a potential risk to tax revenue as there is concern with artificial engineering in order to lower the overall tax burden. This has led to tax integrity measures, which by their very nature can potentially restrict flexibility. For example, LLCs and their members are subject to greater (and potentially more complex rules) when it comes to measuring the cost basis of their membership interests; this then influences members’ ability to utilise allocated losses and the tax treatment of distributions. The flexibility of contributions and distributions for LLPs in the United Kingdom has also raised concerns with the introduction of tax integrity measures. By comparison, the United States’ older tax pass-through entity, the S Corporation, with only one class of membership interest, has fewer integrity rules governing allocations. This Article will critically assess how the flexibility of contributions and distributions by these tax pass-through entities affects the tax rules that apply to their members. We argue that the flexibility of contributions and distributions appears to be a key characteristic demanded by business entities both for commercial and tax reasons. However, investors need to be cognitive of the inherent complexity and costs that this flexibility may entail. Additionally, it is important for governments and revenue authorities not to unduly restrict flexibility with complex tax integrity rules as it is a fine balance between commercial and revenue needs

Executive summary: heart disease and stroke statistics--2013 update: a report from the American Heart Association.

Each year, the American Heart Association (AHA), in conjunction with the Centers for Disease Control and Prevention, the National Institutes of Health, and other government agencies, brings together the most up-to-date statistics on heart disease, stroke, other vascular diseases, and their risk factors and presents them in its Heart Disease and Stroke Statistical Update*The Statistical Update is a valuable resource for researchers, clinicians, healthcare policy makers, media professionals, the lay public, and many others who seek the best national data available on heart disease, stroke, and other cardiovascular disease-related morbidity and mortality and the risks, quality of care, medical procedures and operations, and costs associated with the management of these diseases in a single document*Indeed, since 1999, the Statistical Update has been cited \u3e10 500 times in the literature, based on citations of all annual versions*In 2011 alone, the various Statistical Updates were cited ≈1500 times (data from ISI Web of Science)*In recent years, the Statistical Update has undergone some major changes with the addition of new chapters and major updates across multiple areas, as well as increasing the number of ways to access and use the information assembled*For this year\u27s edition, the Statistics Committee, which produces the document for the AHA, updated all of the current chapters with the most recent nationally representative data and inclusion of relevant articles from the literature over the past year*This year\u27s edition also implements a new chapter organization to reflect the spectrum of cardiovascular health behaviors and health factors and risks, as well as subsequent complicating conditions, disease states, and outcomes*Also, the 2013 Statistical Update contains new data on the monitoring and benefits of cardiovascular health in the population, with additional new focus on evidence-based approaches to changing behaviors, implementation strategies, and implications of the AHA\u27s 2020 Impact Goals*Below are a few highlights from this year\u27s Update . © 2013 American Heart Association, Inc

On the Fractional Wideband and Narrowband Ambiguity Function in Radar and Sonar

The article of record as published may be found at http://dx.doi.org/10.1109/LSP.2006.874436We construct the wideband ambiguity function for signals represented by their fractional Fourier transforms. Because the reflected signal must be represented as a Doppler scaled version of the transmitted signal, this wideband form of ambiguity does not enjoy many of the same properties as the narrowband form (which is formed from a Doppler shifted version of the signal). We present the general result and also examine an approximation appropriate to wideband signals reflected from slowly moving targets.This work was sponsored by the Office of Naval Research

Microlocal Analysis of GTD-based SAR models

We show how to apply the techniques of microlocal analysis to the Potter-Moses attributed scattering center model, which is based on the Geometrical Theory of Diffraction (GTD). The microlocal methods enable us to determine how scattering centers will appear in the radar data. We show also how to extend the model to some multiple-scattering events, and we apply the microlocal techniques to the extended model.This work was supported by the Office of Naval Research and by the Air Force Office of Scientific Research∗ under agreement number F49620-03-1-0051. It was also partially supported by SAIC under a contract from the Air Force Research Laboratory

Synthetic-aperture imaging from high-Doppler-resolution measurements

The article of record as published may be found at http://dx.doi.org/10.1088/0266-5611/21/1/001We develop the theory of radar imaging from data measured by a moving antenna emitting a single-frequency waveform. We show that, under a linearized (Born) scattering model, the signal at a given Doppler shift is due to a superposition of returns from stationary scatterers on a cone whose axis is the flight velocity vector. This cone reduces to a hyperbola when the scatterers are known to lie on a planar surface. In this case, reconstruction of the scatterer locations can be accomplished by a tomographic inversion in which the scattering density function is reconstructed from its integrals over hyperbolas. We give an approximate reconstruction formula and analyse the resolution of the resulting image. We provide a numerical shortcut and show results of numerical tests in a simple case.This work was supported by the Office of Naval Research, the Air Force Office of Scientific Research under agreement F49620-03-1-0051, and by the Air Force Research Laboratory appunder agreement FA87500308276. This work was also supported in part by Rensselaer Polytechnic Institute, by the NSF-supported UCLA Institute for Pure and Applied Mathematics and by the NSF Focused Research Groups in the Mathematical Sciences program