One curve-fit method for the evaluation of the total distortion of sinusoidal signal

2010 ◽  
Author(s):  
Hui Wang ◽  
Yunjian Ge ◽  
Zhengshi Liu ◽  
Huanjin Liu ◽  
Liang Xu
Keyword(s):  
Sinusoidal Signal ◽  
Curve Fit ◽  
Total Distortion

Rapid prototyping of algorithmic A/D converters based on FPAA devices

2013 ◽  
Vol 61 (3) ◽  
pp. 691-696 ◽  
Author(s):  
R. Suszynski ◽  
K. Wawryn
Keyword(s):  
Rapid Prototyping ◽  
Sinusoidal Signal ◽  
Digital Converter ◽  
Mixed Signal ◽  
Analog Digital Converter ◽  
Signal Systems ◽  
Programmable Analog ◽  
Field Programmable ◽  
Field Programmable Analog Array

Abstract A rapid prototyping method for designing mixed signal systems has been presented in the paper. The method is based on implementation of the field programmable analog array (FPAA) to configure and reconfigure mixed signal systems. A serial algorithmic analog digital converter has been used as an example. Three converter architectures have been selected and implemented FPAA device. To verify and illustrate converters operation and prototyping capabilities, implemented converters have been excited by a sinusoidal signal. Analog sinusoidal excitations, digital responses and sinusoidal waveforms after reconstruction are presented.

scholarly journals Start of the Green Season and Normalized Difference Vegetation Index in Alaska’s Arctic National Parks

2021 ◽  
Vol 13 (13) ◽  
pp. 2554
Author(s):  
David K. Swanson
Keyword(s):  
National Parks ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Free Surfaces ◽  
Modis Ndvi ◽  
Curve Fit ◽  
Winter Snow ◽  
Systematic Sample ◽  
Low Levels ◽  
Northern Alaska

Daily Normalized Difference Vegetation Index (NDVI) values from the MODIS Aqua and Terra satellites were compared with on-the-ground camera observations at five locations in northern Alaska. Over half of the spring rise in NDVI was due to the transition from the snow-covered landscape to the snow-free surface prior to the deciduous leaf-out. In the fall after the green season, NDVI fluctuated between an intermediate level representing senesced vegetation and lower values representing clouds and intermittent snow, and then dropped to constant low levels after establishment of the permanent winter snow cover. The NDVI value of snow-free surfaces after fall leaf senescence was estimated from multi-year data using a 90th percentile smoothing spline curve fit to a plot of daily NDVI values vs. ordinal date. This curve typically showed a flat region of intermediate NDVI values in the fall that represent cloud- and snow-free days with senesced vegetation. This “fall plateau” was readily identified in a large systematic sample of MODIS NDVI values across the study area, in typical tundra, shrub, and boreal forest environments. The NDVI level of the fall plateau can be extrapolated to the spring rising leg of the annual NDVI curve to approximate the true start of green season.

Remarks on algorithm 91: Chebyshev curve fit

1964 ◽  
Vol 7 (5) ◽  
pp. 296
Author(s):  
Peter Naur
Keyword(s):  
Curve Fit

scholarly journals A Case Study on Soundscape Analysis for the Historical and Ethnic Village of Dong Nationality in Zhaoxing County

Acoustics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 221-234
Author(s):  
Zhiyong Deng ◽  
Kexin Dong ◽  
Danfeng Bai ◽  
Kaicheng Tong ◽  
Aili Liu
Keyword(s):  
Sound Pressure ◽  
Subjective Experience ◽  
Guizhou Province ◽  
Music Listening ◽  
Ethnic Music ◽  
Curve Fit ◽  
Sound Event ◽  
Sound Environment ◽  
Independent Variable

A soundscape is a sound environment of the awareness of auditory perception and social or cultural understandings. Based on a soundscape investigation in 2019 in the historical and ethnic village of Dong Nationality in Zhaoxing County, Guizhou Province of China, a case study on the soundscape analysis with the acoustical sound pressure level and an impressive sound event or soundmark is introduced in this paper. Furthermore, in order to determine the subjective soundscape experience and its influence by the length of background music listening, the independent variable “Length of Listening” and six adjective pairs, such as “Monotonous” to “Rich”, “Clamorous” to “Quiet”, “Stressing” to “Relaxing”, “Boring” to “Vivid”, “Noisy” to “Musical” and “Disliked” to “Preferable” are chosen to obtain a curve-fit, which shows that the length of the music listening background has a higher correlation to the subjective experience, and no sufficient attention has been paid to the context of the traditional soundscape preservation, ethnic music and quiet and soft ambient sounds.

Rheological studies of SBS/EVA blends modified with bio-based cashew nut shell liquid

2021 ◽  
pp. 009524432199040
Author(s):  
Isabela Pinto Ferreira ◽  
Alex da Silva Sirqueira ◽  
Taiane Andre dos Santos ◽  
Monica Feijo Naccache ◽  
Bluma Guenther Soares
Keyword(s):  
Ethylene Vinyl Acetate ◽  
Rheological Parameters ◽  
Creep Recovery ◽  
Cashew Nut Shell Liquid ◽  
Cashew Nut ◽  
Curve Fit ◽  
Significant Difference ◽  
Cashew Nut Shell ◽  
S Model ◽  
Styrene Butadiene

Research on bio-plasticizers is a topic of strategic interest in polymer blends. A bio-plasticizer, cashew nut shell liquid (CNSL), was studied in blends of ethylene-vinyl acetate copolymer (EVA) and styrene-butadiene-styrene copolymer (SBS). In the literature does not report the addition of plasticizers to SBS/EVA blend. Statistical analyses showed that there was a significant difference in mechanical properties (tension at break, hardness and elongation at break) vs. the unplasticized blend. The minimum CNSL concentration required for a statistical difference was 10 phr. The Carreau-Yasuda rheological model was used to obtain rheological parameters in these blends. The plasticizing influence of CNSL was confirmed by rheology. The effects of CNSL on creep and recovery were evaluated for the SBS/EBA blends. Burger´s model explained well SBS/EVA creep compliance. Moreover, its parameters (Newtonian dashpots and Hookean springs) were evaluated as a function of the CNSL concentrations. The bio-plasticizer concentration influenced significant correlations among the rheological creep-recovery tests, thus enabling a considerable increase in the elastic phase. Experimental creep-recovery data and curve fit were in good agreement.

scholarly journals Variability of the total ozone trend over Europe for the period 1950–2004 derived from reconstructed data

2008 ◽  
Vol 8 (11) ◽  
pp. 2847-2857 ◽  
Author(s):  
J. W. Krzyścin ◽  
J. L. Borkowski
Keyword(s):  
Total Ozone ◽  
A Priori ◽  
Smooth Curve ◽  
Ozone Level ◽  
Svalbard Archipelago ◽  
Small Areas ◽  
Ozone Data ◽  
Curve Fit ◽  
Long Term Changes

Abstract. The total ozone data over Europe are available for only few ground-based stations in the pre-satellite era disallowing examination of the spatial trend variability over the whole continent. A need of having gridded ozone data for a trend analysis and input to radiative transfer models stimulated a reconstruction of the daily ozone values since January 1950. Description of the reconstruction model and its validation were a subject of our previous paper. The data base used was built within the objectives of the COST action 726 "Long-term changes and climatology of UV radiation over Europe". Here we focus on trend analyses. The long-term variability of total ozone is discussed using results of a flexible trend model applied to the reconstructed total ozone data for the period 1950–2004. The trend pattern, which comprises both anthropogenic and "natural" component, is not a priori assumed but it comes from a smooth curve fit to the zonal monthly means and monthly grid values. The ozone long-term changes are calculated separately for cold (October–next year April) and warm (May–September) seasons. The confidence intervals for the estimated ozone changes are derived by the block bootstrapping. The statistically significant negative trends are found almost over the whole Europe only in the period 1985–1994. Negative trends up to −3% per decade appeared over small areas in earlier periods when the anthropogenic forcing on the ozone layer was weak . The statistically positive trends are found only during warm seasons 1995–2004 over Svalbard archipelago. The reduction of ozone level in 2004 relative to that before the satellite era is not dramatic, i.e., up to ~−5% and ~−3.5% in the cold and warm subperiod, respectively. Present ozone level is still depleted over many popular resorts in southern Europe and northern Africa. For high latitude regions the trend overturning could be inferred in last decade (1995–2004) as the ozone depleted areas are not found there in 2004 in spite of substantial ozone depletion in the period 1985–1994.

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