Two approaches to the concurrent implementation of the prime factor algorithm on a hypercube

On sequential computers, the prime factor algorithm (PFA) allows the Computation of the discrete Fourier transform (DFT) with a higher efficiency than the traditional Cooley‐Tukey FFT algorithm (CTA). However, the PFA requires substantial data movement, which poses a challenging problem for distributed‐memory multi‐processor systems. In this paper, two approaches for a concurrent implementation of the PFA on these structures are presented. In the first approach, the concurrent PFA runs on all nodes of the multi‐processor system, which is inefficient on large configurations due to the large communication overhead. A second approach developed to reduce this bottleneck is also presented. These solutions have been benchmarked on Caltech hypercubes, and the performances achieved are reported. In both approaches, the crystal_router algorithm was exploited as a concurrent technique for communicating data among nodes

SABRINA the Italian Mission for Endowing COSMO-SkyMed with Bistatic and Interferometric Capabilities

This paper focuses main characteristics and expected performance of SABRINA (System for Advanced Bistatic and Radar INterferometric Applications) Mission which has been selected by the Italian Space Agency for complementing COSMO-SkyMed, the Italian constellation for high spatial and temporal resolution SAR imaging of the Earth. After a brief presentation of COSMO-SkyMed development status, the key aspects of the mission and expected applications and products are dealt in detail

Two approaches to the concurrent implementation of the prime factor algorithm on a hypercube

On sequential computers, the prime factor algorithm (PFA) allows the Computation of the discrete Fourier transform (DFT) with a higher efficiency than the traditional Cooley‐Tukey FFT algorithm (CTA). However, the PFA requires substantial data movement, which poses a challenging problem for distributed‐memory multi‐processor systems. In this paper, two approaches for a concurrent implementation of the PFA on these structures are presented. In the first approach, the concurrent PFA runs on all nodes of the multi‐processor system, which is inefficient on large configurations due to the large communication overhead. A second approach developed to reduce this bottleneck is also presented. These solutions have been benchmarked on Caltech hypercubes, and the performances achieved are reported. In both approaches, the crystal_router algorithm was exploited as a concurrent technique for communicating data among nodes

Two approaches to the concurrent implementation of the prime factor algorithm on a hypercube

On sequential computers, the prime factor algorithm (PFA) allows the computation of the discrete Fourier transform (DFT) with a higher efficiency than the traditional Cooley-Tukey FFT algorithm (CTA). However, the PFA requires substantial data movement, which poses a challenging problem for distributed-memory multi-processor systems. In this paper, two approaches for a concurrent implementation of the PFA on these structures are presented. In the first approach, the concurrent PFA runs on all nodes or the multi-processor system, which is inefficient on large configurations due to the large communication overhead. A second approach developed to reduce this bottleneck is also presented. These solutions have been benchmarked on Caltech hypercubes, and the performances achieved are reported. In both approaches, the crystal-router algorithm was exploited as a concurrent technique for communicating data among nodes.112sciescopu

Characterization of nebulization generated aerosol particles dispersion and deposition by total reflection X-ray fluorescence

To prevent air pollution and achieve air quality regulations, it is essential to develop analytical techniques that can determine the concentration of metals in aerosol particles, both in the gas phase and after collection onto filters. Total reflection X-ray fluorescence spectroscopy (TXRF) and laser-induced breakdown spectroscopy (LIBS) are emerging as complementary techniques for determining the elemental composition of aerosol particles. The accuracy of their results relies on calibration methods based on aerosol and multi-element filters representative of the on-line measurement conditions and particulate collection for off-line measurement, respectively. In this paper we propose a novel methodology for characterizing nebulization generated aerosol particles dispersion and deposition by means of TXRF to assess the use of an aerosol generator to produce calibration samples for LIBS and TXRF analysis. Particles concentration and size distribution of the aerosol produced by nebulizing a Cu salt aqueous solution are measured inside a glove box modifying the production parameters and collecting the corresponding particulate deposited on reflectors. The most stable conditions are observed at average flow rate and selected for studying the aerosol spatial distribution. The Cu mass collected on reflectors positioned at a fixed distance and radial geometry with respect to the nozzle exit is measured by TXRF and increases linearly with time. Results suggest that this experimental configuration could be used to realize calibration samples for TXRF analysis representative of particulate deposition. The use of these aerosols as LIBS calibration samples could lead to significant errors due to the observed flow asymmetry.Copyright (c) 2022 American Association for Aerosol Researc

The PRISMA imaging spectroscopy mission: overview and first performance analysis

The PRISMA satellite mission launched on March 22nd, 2019 is one of the latest spaceborne imaging spectroscopy mission for Earth Observation. The PRISMA satellite comprises a high-spectral resolution VNIR-SWIR imaging spectrometer and a panchromatic camera. In summer 2019, first operations during the commissioning phase were mainly devoted to acquisitions in specific areas for evaluating instrument functioning, in-flight performance, and mission data product accuracy. A field and airborne campaign was carried out over an agriculture area in Italy to collect in-situ multi-source spectroscopy measurements at different scales simultaneously with PRISMA. The spectral, radiometric and spatial performance of PRISMA Level 1 Top-Of-Atmosphere radiance (LTOA) product were analyzed. The in-situ surface reflectance measurements over different landcovers were propagated to LTOA using MODTRAN5 radiative transfer simulations and compared with satellite observations. Overall, this work offers a first quantitative evaluation about the PRISMA mission performance and imaging spectroscopy LTOA data product consistency. Our results show that the spectral smile is less than 5 nm, the average spectral resolution is 13 nm and 11 nm (VNIR and SWIR respectively) and it varies ±2 nm across track. The radiometric comparison between PRISMA and field/airborne spectroscopy shows a difference lower than 5% for NIR and SWIR, whereas it is included in the 2–7% range in the VIS. The estimated instrument signal to noise ratio (SNR) is ≈400–500 in the NIR and part of the SWIR (1600 nm). The VNIR-to-SWIR spatial co-registration error is below 8 m and the spatial resolution is 37.11 m and 38.38 m for VNIR and SWIR respectively. The results are in-line with the expectations and mission requirements and indicate that acquired images are suitable for further scientific applications. However, this first assessment is based on data from a rural area and this cannot be fully exhaustive. Further studies are needed to confirm the performance for other land cover types like snow, inland and coastal waters, deserts or urban areas