1,614 research outputs found

    Set projection algorithms for blind ptychographic phase retrieval

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    Set projection algorithms are a class of algorithms used in ptychography to help improve the quality of the reconstructed images. The set projection step is important because it helps to ensure that the reconstructed image satisfies the physical constraints, which can improve the quality of the final result. A new projection algorithm that combines the advantages of the existing algorithms is proposed and offers the possibility of a parallel algorithm for iterative algorithms.Comment: Presented in ISCS2

    Material Properties Measurements for Selected Materials

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    Hugoniot equation of state measurements were made on Coconino sandstone, Vacaville basalt, Kaibab limestone, Mono Crater, pumice and Zelux (a polycarbonate resin) for pressures to 2 Mb. A single data point was obtained for fused quartz at 1.6 Mb. In addition to the hugoniot studies, the uniaxial compressive stress behavior of Vacaville basalt and Zelux was investigated at strain rates from about 10(exp -5)/sec to 10(exp 3)/second. The data presented include the stress - strain relations as a function of strain rate for these two materials

    Multi-slice ptychographic tomography

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    Ptychography is a form of Coherent Diffractive Imaging, where diffraction patterns are processed by iterative algorithms to recover an image of a specimen. Although mostly applied in two dimensions, ptychography can be extended to produce three dimensional images in two ways: via multi-slice ptychography or ptychographic tomography. Ptychographic tomography relies on 2D ptychography to supply projections to conventional tomographic algorithms, whilst multi-slice ptychography uses the redundancy in ptychographic data to split the reconstruction into a series of axial slices. Whilst multi-slice ptychography can handle multiple-scattering thick specimens and has a much smaller data requirement than ptychographic tomography, its depth resolution is relatively poor. Here we propose an imaging modality that combines the benefits of the two approaches, enabling isotropic 3D resolution imaging of thick specimens with a small number of angular measurements. Optical experiments validate our proposed method

    REDEPEND-REACT: an architecture analysis tool

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    The i* approach includes the construction of strategic dependency models (SD) developed to model information systems that can be applied in a wide variety of contexts. We are interested in the formulation of metrics over i* models to be used in components system architectures analysis. These metrics are defined to analyse the models with respect to some properties that are interesting for the system being modelled, such as security, efficiency or accuracy. Metrics are defined in terms of the actors and dependencies of the models and the results of their evaluation are used to inform multiple component selection. As the definition and evaluation of the property metrics are cumbersome activities, the need of tool support arises. Thus, we have enlarged REDEPEND, a Microsoft Visio plug-in that graphically models system goals using the i* formalism, to support the definition and evaluation of architectural properties obtaining the REDEPEND-REACT prototype.Peer ReviewedPostprint (published version
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