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Articoli di riviste sul tema "Distance spectra"

Autore: Grafiati

Pubblicato: 12 ottobre 2024

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1

Navarro, Silvana G., Romano L. M. Corradi e Antonio Mampaso. "Distance determination to PNe using the extinction-distance method". Proceedings of the International Astronomical Union 7, S283 (luglio 2011): 460–61. http://dx.doi.org/10.1017/s1743921312011921.

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AbstractWe present individual distances to three PNe: NGC 6537, NGC 6781 and NGC 7027, determined by the extinction-distance method. These objects are part of a larger sample (35) of PNe that we observed at ORM. In order to apply this method, and to obtain accurate distances, we determined the spectral type of 40 to 60 stars in the line of sight of each PNe. This implied the necessity of classifying few thousands of stellar spectra with S/N ratio between 10 and 60. To solve such need we developed an ANN system to perform automatic spectral classification which could classify spectra with S/N ratio as low as 20 with an accuracy better than 2 spectral subtypes. In this poster we compare the accuracy of such distances with previous distance determinations using other methods. We conclude that it is possible to use this method to obtain the distance of a large number of PNe with better precision.

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2

Houston, Heidi, e Hiroo Kanamori. "Comparison of strong-motion spectra with teleseismic spectra for three magnitude 8 subduction-zone earthquakes". Bulletin of the Seismological Society of America 80, n. 4 (1 agosto 1990): 913–34. http://dx.doi.org/10.1785/bssa0800040913.

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Abstract We studied strong-motion spectra observed for three Mw 7.8 to 8.0 earthquakes (the 1985 Michoacán, Mexico; 1985 Valparaíso, Chile; and 1983 Akita-Oki, Japan earthquakes). We determined the decay of spectral amplitude with distance from the station, considering different measures of distance from a finite fault. We compared strong-motion spectra (Fourier acceleration spectra) observed for these three earthquakes with those estimated from the source spectrum determined from teleseismic P waves. We scaled the teleseismic source spectra to produce reference strong-motion spectra at periods from 1 to 10 sec using a simple physical model of far-field S body waves from a point source recorded at the surface of a homogeneous half-space. For all three earthquakes the reference spectral amplitudes at periods of 1 to 5 sec are about half the observed ones at distances of about 50 km. The difference increases as the distance increases. At distances of 200 to 300 km, the reference spectrum is about 1/10 of the observed one. The difference between the reference and the observed spectrum is attributed to the contribution of phases other than direct S waves and to site response. We applied corrections for the finiteness (spatial extent) of the source using a simple model of rupture propagation on a dipping two-dimensional fault. Including the source finiteness did not improve the estimate substantially at periods from 1 to 20 sec, but it modeled significant changes in the signal duration as a function of azimuth for the 1985 Michoacán earthquake. Our results can be used to establish empirical relations between the observed spectra and the half-space responses, depending on the distance and the site condition. If such empirical relations can be established, source spectra determined from teleseismic records may be used to estimate strong motions.

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Lin, Huiqiu, Dan Li e Kinkar Ch Das. "Distance between distance spectra of graphs". Linear and Multilinear Algebra 65, n. 12 (16 gennaio 2017): 2538–50. http://dx.doi.org/10.1080/03081087.2017.1278737.

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4

Cvetkovic, Dragos. "Spectral recognition of graphs". Yugoslav Journal of Operations Research 22, n. 2 (2012): 145–61. http://dx.doi.org/10.2298/yjor120925025c.

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At some time, in the childhood of spectral graph theory, it was conjectured that non-isomorphic graphs have different spectra, i.e. that graphs are characterized by their spectra. Very quickly this conjecture was refuted and numerous examples and families of non-isomorphic graphs with the same spectrum (cospectral graphs) were found. Still some graphs are characterized by their spectra and several mathematical papers are devoted to this topic. In applications to computer sciences, spectral graph theory is considered as very strong. The benefit of using graph spectra in treating graphs is that eigenvalues and eigenvectors of several graph matrices can be quickly computed. Spectral graph parameters contain a lot of information on the graph structure (both global and local) including some information on graph parameters that, in general, are computed by exponential algorithms. Moreover, in some applications in data mining, graph spectra are used to encode graphs themselves. The Euclidean distance between the eigenvalue sequences of two graphs on the same number of vertices is called the spectral distance of graphs. Some other spectral distances (also based on various graph matrices) have been considered as well. Two graphs are considered as similar if their spectral distance is small. If two graphs are at zero distance, they are cospectral. In this sense, cospectral graphs are similar. Other spectrally based measures of similarity between networks (not necessarily having the same number of vertices) have been used in Internet topology analysis, and in other areas. The notion of spectral distance enables the design of various meta-heuristic (e.g., tabu search, variable neighbourhood search) algorithms for constructing graphs with a given spectrum (spectral graph reconstruction). Several spectrally based pattern recognition problems appear in many areas (e.g., image segmentation in computer vision, alignment of protein-protein interaction networks in bio-informatics, recognizing hard instances for combinatorial optimization problems such as the travelling salesman problem). We give a survey of such and other graph spectral recognition techniques used in computer sciences.

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5

Garratt, R. C., R. W. Evans, S. S. Hasnain e P. F. Lindley. "An extended-X-ray-absorption-fine-structure investigation of diferric transferrins and their iron-binding fragments". Biochemical Journal 233, n. 2 (15 gennaio 1986): 479–84. http://dx.doi.org/10.1042/bj2330479.

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Iron K-edge extended-X-ray-absorption-fine-structure (e.x.a.f.s.) spectra were recorded for diferric human and rabbit serum transferrins and for diferric chicken ovotransferrin in aqueous solution; for ovotransferrin e.x.a.f.s. spectra from the N-terminal and C-terminal domain fragments were also measured. The overall spectral profiles closely resemble one another, indicating similar iron-binding sites. The simulation of the diferric ovotransferrin spectrum suggests a first co-ordination shell consisting of six low-Z ligands (nitrogen/oxygen), two ligands at a distance of approx. 0.185 nm (1.85 A) and four ligands at approx. 0.204 nm (2.04 A). The two shorter distances may correspond to Fe-O (tyrosine), whereas the longer distance is consistent with Fe-N (histidine) and Fe-O (water). Detailed analysis of the spectra of the N-terminal and C-terminal fragments indicates a difference in the short ligand distance.

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6

Balasubramanian, K. "Distance Spectra and Distance Polynomials of Fullerenes". Journal of Physical Chemistry 99, n. 27 (luglio 1995): 10785–96. http://dx.doi.org/10.1021/j100027a018.

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7

Paul, Somnath. "On distance and distance Laplacian spectra of corona of two graphs". Discrete Mathematics, Algorithms and Applications 08, n. 01 (26 febbraio 2016): 1650007. http://dx.doi.org/10.1142/s1793830916500075.

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Corona of two graphs has been defined in [F. Harary, Graph Theory (Addison-Wesley, 1969)]. In this paper, we study the distance and the distance Laplacian spectra of corona of two graphs and describe the complete distance (distance Laplacian) spectrum for some particular cases. As an application, we show that the corona operation can be used to create distance singular graphs. We also show that these results enable us to construct infinitely many pairs of distance (respectively, distance Laplacian) cospectral graphs. Last, we give a graph transformation and discuss its effect on the distance Laplacian spectral radius.

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8

Margolis, J. S. "Spectra at a Distance". Science 259, n. 5098 (19 febbraio 1993): 1209–10. http://dx.doi.org/10.1126/science.259.5098.1209.

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9

Wang, Chun, Yang Huang, Haibo Yuan, Huawei Zhang, Maosheng Xiang e Xiaowei Liu. "The Value-added Catalog for LAMOST DR8 Low-resolution Spectra". Astrophysical Journal Supplement Series 259, n. 2 (28 marzo 2022): 51. http://dx.doi.org/10.3847/1538-4365/ac4df7.

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Abstract We present a value-added catalog containing stellar parameters estimated from 7.10 million low-resolution spectra for 5.16 million unique stars with spectral signal-to-noise ratios (S/N) higher than 10 obtained by the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Galactic spectroscopic surveys. The catalog presents values of stellar atmospheric parameters (effective temperature T eff, surface gravity log g, metallicity [Fe/H]/[M/H]), α-element to metal abundance ratio [α/M], carbon and nitrogen to iron abundance ratios [C/Fe] and [N/Fe], and 14 bands’ absolute magnitudes deduced from LAMOST spectra using the neural network method. The spectrophotometric distances of those stars are also provided based on the distance modulus. For stars with a spectral S/N larger than 50, precisions of T eff, log g, [Fe/H], [M/H], [C/Fe], [N/Fe], and [α/M] are 85 K, 0.098 dex, 0.05 dex, 0.05 dex, 0.052 dex, 0.082 dex, and 0.027 dex, respectively. The errors of 14 band’s absolute magnitudes are 0.16–0.22 mag for stars with a spectral S/N larger than 50. The spectrophotometric distance is accurate to 8.5% for stars with a spectral S/N larger than 50 and is more accurate than the geometrical distance for stars with a distance larger than 2.0 kpc. Our estimates of [Fe/H] are reliable down to [Fe/H] ∼−3.5 dex, significantly better than previous results. The catalog provides 26,868 unique very metal-poor star candidates ([Fe/H] ≤−2.0). The catalog would be a valuable dataset to study the structure and evolution of the galaxy, especially the solar neighborhood and the outer disk.

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Abdollahi, Alireza, Shahrooz Janbaz e Mohammad Reza Oboudi. "Distance between spectra of graphs". Linear Algebra and its Applications 466 (febbraio 2015): 401–8. http://dx.doi.org/10.1016/j.laa.2014.10.020.

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11

Weathers, A. D., S. A. Altekar e J. K. Wolf. "Distance spectra for PRML channels". IEEE Transactions on Magnetics 33, n. 5 (1997): 2809–11. http://dx.doi.org/10.1109/20.617738.

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12

Nokrane, Abdelkrim. "Estimating matching distance between spectra". Operators and Matrices, n. 4 (2009): 503–8. http://dx.doi.org/10.7153/oam-03-27.

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13

Bozorgnia, Yousef, Mahmoud M. Hachem e Kenneth W. Campbell. "Ground Motion Prediction Equation (“Attenuation Relationship”) for Inelastic Response Spectra". Earthquake Spectra 26, n. 1 (febbraio 2010): 1–23. http://dx.doi.org/10.1193/1.3281182.

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This paper presents the process and fundamental results of a comprehensive ground motion prediction equation (GMPE, or “attenuation” relationship) developed for inelastic response spectra. We used over 3,100 horizontal ground motions recorded in 64 earthquakes with moment magnitudes ranging from 4.3–7.9 and rupture distances ranging from 0.1–199 km. For each record, we computed inelastic spectra for ductility ranging from one (elastic response) to eight. Our GMPE correlates inelastic spectral ordinates to earthquake magnitude, site-to-source distance, fault mechanism, local soil properties, and basin effects. The developed GMPE is used in both deterministic and probabilistic hazard analyses to directly generate inelastic spectra. This is in contrast to developing “attenuation” relationships for elastic response spectra, carrying out a hazard analysis, and subsequently adopting approximate rules to derive inelastic response from elastic spectra.

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14

Siebert, M. R., R. J. Foley, D. O. Jones e K. W. Davis. "A possible distance bias for type Ia supernovae with different ejecta velocities". Monthly Notices of the Royal Astronomical Society 493, n. 4 (3 marzo 2020): 5713–25. http://dx.doi.org/10.1093/mnras/staa577.

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ABSTRACT After correcting for their light-curve shape and colour, Type Ia supernovae (SNe Ia) are precise cosmological distance indicators. However, there remains a non-zero intrinsic scatter in the differences between measured distance and that inferred from a cosmological model (i.e. Hubble residuals or HRs), indicating that SN Ia distances can potentially be further improved. We use the open-source relational data base kaepora to generate composite spectra with desired average properties of phase, light-curve shape, and HR. At many phases, the composite spectra from two subsamples with positive and negative average HRs are significantly different. In particular, in all spectra from 9 d before to 15 d after peak brightness, we find that SNe with negative HRs have, on average, higher ejecta velocities (as seen in nearly every optical spectral feature) than SNe with positive HRs. At +4 d relative to B-band maximum, using a sample of 62 SNe Ia, we measure a 0.091 ± 0.035 mag (2.7σ) HR step between SNe with Si ii λ6355 line velocities ($v_{Si\, rm{\small II}}$) higher/lower than −11 000 km s−1 (the median velocity). After light-curve shape and colour correction, SNe with higher velocities tend to have underestimated distance moduli relative to a cosmological model. The intrinsic scatter in our sample reduces from 0.094 to 0.082 mag after making this correction. Using the Si ii λ6355 velocity evolution of 115 SNe Ia, we estimate that a velocity difference >500 km s−1 exists at each epoch between the positive-HR and negative-HR samples with 99.4 per cent confidence. Finally at epochs later than +37 d, we observe that negative-HR composite spectra tend to have weaker spectral features in comparison to positive-HR composite spectra.

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Chen, Jianbo, Qun Zhou, Isao Noda e Suqin Sun. "Quantitative Classification of Two-Dimensional Correlation Spectra". Applied Spectroscopy 63, n. 8 (agosto 2009): 920–25. http://dx.doi.org/10.1366/000370209788964520.

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Two-dimensional (2D) correlation spectroscopy, which takes advantage of the apparent enhancement of spectral resolution, is known to be useful in qualitative discrimination of seemingly similar samples. The possibility of quantitative classification of 2D correlation spectra is even more desirable. Two useful parameters, namely Euclidian distance and correlation coefficient between 2D correlation spectra, are introduced for this purpose. Dry and sweet red wine samples are used to demonstrate the utility of these parameters. The distances between the 2D infrared (IR) spectra of sweet and dry red wines are roughly proportional to the differences of sugar contents in them. The result shows that the two parameters are useful measures for the quantitative evaluation of the similarity among the samples and their corresponding 2D correlation spectra.

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Ilić, Aleksandar. "Distance spectra and distance energy of integral circulant graphs". Linear Algebra and its Applications 433, n. 5 (ottobre 2010): 1005–14. http://dx.doi.org/10.1016/j.laa.2010.04.034.

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17

da Cunha Lima, A. T., I. C. da Cunha Lima e M. P. de Almeida. "Analysis of turbulence power spectra and velocity correlations in a pipeline with obstructions". International Journal of Modern Physics C 28, n. 02 (febbraio 2017): 1750019. http://dx.doi.org/10.1142/s012918311750019x.

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We calculate the power spectral density and velocity correlations for a turbulent flow of a fluid inside a duct. Turbulence is induced by obstructions placed near the entrance of the flow. The power spectral density is obtained for several points at cross-sections along the duct axis, and an analysis is made on the way the spectra changes according to the distance to the obstruction. We show that the differences on the power spectral density are important in the lower frequency range, while in the higher frequency range, the spectra are very similar to each other. Our results suggest the use of the changes on the low frequency power spectral density to identify the occurrence of obstructions in pipelines. Our results show some frequency regions where the power spectral density behaves according to the Kolmogorov hypothesis. At the same time, the calculation of the power spectral densities at increasing distances from the obstructions indicates an energy cascade where the spectra evolves in frequency space by spreading the frequency amplitude.

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18

Zhang, Zhiyong, Shuo Wang e Yanqing Zhang. "Non-Destructive Detection of Water Content in Pork Based on NIR Spatially Resolved Spectroscopy". Agriculture 13, n. 11 (8 novembre 2023): 2114. http://dx.doi.org/10.3390/agriculture13112114.

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Water is one of the important factors affecting pork quality. In this study, near-infrared (NIR) spatially resolved (SR) spectroscopy was used to detect the water content of pork. The SR spectra of 150 pork samples were collected within the light source–detector (LS-D) distance range of 4–20 mm (distance interval 1 mm). Models were established based on single-point SR spectra of 17 different LS-D distances and combination SR spectra. The results indicated that combination SR spectra achieved better model performance than the single-point SR spectra, and the LS-D distance significantly affected the model accuracy. The optimal LS-D distance combination of 5, 7, 10, and 12 mm provided the best detection model with the calibration determination coefficient (R2C) of 0.915 and prediction determination coefficient (R2P) of 0.878. Using the competitive adaptive reweighted sampling (CARS) algorithm, 24 characteristic wavelengths were selected. The model built with the characteristic wavelengths also exhibited good detection accuracy, with a R2C of 0.909 and a R2P of 0.867, and the number of wavelengths was greatly reduced compared to the full-wavelength model. This study demonstrated that SR spectroscopy combined with the optimized LS-D distances and screened characteristic wavelengths can be a powerful tool for detecting the water content of pork.

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Hayat, Sakander, Asad Khan e Mohammed J. F. Alenazi. "On Some Distance Spectral Characteristics of Trees". Axioms 13, n. 8 (23 luglio 2024): 494. http://dx.doi.org/10.3390/axioms13080494.

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Graham and Pollack in 1971 presented applications of eigenvalues of the distance matrix in addressing problems in data communication systems. Spectral graph theory employs tools from linear algebra to retrieve the properties of a graph from the spectrum of graph-theoretic matrices. The study of graphs with “few eigenvalues” is a contemporary problem in spectral graph theory. This paper studies graphs with few distinct distance eigenvalues. After mentioning the classification of graphs with one and two distinct distance eigenvalues, we mainly focus on graphs with three distinct distance eigenvalues. Characterizing graphs with three distinct distance eigenvalues is “highly” non-trivial. In this paper, we classify all trees whose distance matrix has precisely three distinct eigenvalues. Our proof is different from earlier existing proof of the result as our proof is extendable to other similar families such as unicyclic and bicyclic graphs. The main tools which we employ include interlacing and equitable partitions. We also list all the connected graphs on ν ≤ 6 vertices and compute their distance spectra. Importantly, all these graphs on ν ≤ 6 vertices are determined from their distance spectra. We deliver a distance cospectral pair of order 7, thus making it a distance cospectral pair of the smallest order. This paper is concluded with some future directions.

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20

B S, Durgi, Umesh Poojari, Revankar D S e Hampiholi P R. "Distance Polynomial, Distance Spectra And Distance Energy Of Some Edge Deleted Graphs". International Journal of Mathematics Trends and Technology 67, n. 7 (25 luglio 2021): 94–103. http://dx.doi.org/10.14445/22315373/ijmtt-v67i7p512.

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Gopalapillai, I., e D. C. Scaria. "THE DISTANCE RELATED SPECTRA OF SOME SUBDIVISION RELATED GRAPHS". Journal of Computer Science and Applied Mathematics 3, n. 1 (29 giugno 2021): 22–36. http://dx.doi.org/10.37418/jcsam.3.1.4.

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Let $G$ be a connected graph with a distance matrix $D$. The distance eigenvalues of $G$ are the eigenvalues of $D$, and the distance energy $E_D(G)$ is the sum of its absolute values. The transmission $Tr(v)$ of a vertex $v$ is the sum of the distances from $v$ to all other vertices in $G$. The transmission matrix $Tr(G)$ of $G$ is a diagonal matrix with diagonal entries equal to the transmissions of vertices. The matrices $D^L(G)= Tr(G)-D(G)$ and $D^Q(G)=Tr(G)+D(G)$ are, respectively, the Distance Laplacian and the Distance Signless Laplacian matrices of $G$. The eigenvalues of $D^L(G)$ ( $D^Q(G)$) constitute the Distance Laplacian spectrum ( Distance Signless Laplacian spectrum ). The subdivision graph $S(G)$ of $G$ is obtained by inserting a new vertex into every edge of $G$. We describe here the Distance Spectrum, Distance Laplacian spectrum and Distance Signless Laplacian spectrum of some types of subdivision related graphs of a regular graph in the terms of its adjacency spectrum. We also derive analytic expressions for the distance energy of $\bar{S}(C_p)$, partial complement of the subdivision of a cycle $C_p$ and that of $\overline {S\left( {C_p }\right)}$, complement of the even cycle $C_{2p}$.

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Gawinkowski, Sylwester, Agnieszka Kamińska, Tomasz Roliński e Jacek Waluk. "A new algorithm for identification of components in a mixture: application to Raman spectra of solid amino acids". Analyst 139, n. 22 (2014): 5755–64. http://dx.doi.org/10.1039/c4an01159g.

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Bozorgnia, Youself, Mansour Niazi e Kenneth W. Campbell. "Characteristics of Free-Field Vertical Ground Motion during the Northridge Earthquake". Earthquake Spectra 11, n. 4 (novembre 1995): 515–25. http://dx.doi.org/10.1193/1.1585825.

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Characteristics of response spectra of free-field vertical ground motion recorded during the 1994 Northridge earthquake are examined. Dependence of vertical and horizontal response spectra, and their ratio, on the site-to-source distance is investigated through development of attenuation relationships for vertical and horizontal spectral ordinates. The database includes 123 response spectra of the motions recorded at 41 alluvial sites. Vertical-to-horizontal (V/H) response spectral ratio is found to be strongly dependent on period and distance of site to the seismic source. V/H spectral ratio largely exceeds the commonly assumed value of 2/3, at short periods in the near-field region. The main characteristics of V/H spectral ratio for the Northridge earthquake are found to be qualitatively similar to those observed in the 1989 Loma Prieta, California, and in several other earthquakes recorded over the SMART-1 array in Taiwan. These characteristics are very likely to be universal.

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Boatwright, John. "Regional propagation characteristics and source parameters of earthquakes in northeastern North America". Bulletin of the Seismological Society of America 84, n. 1 (1 febbraio 1994): 1–15. http://dx.doi.org/10.1785/bssa0840010001.

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Abstract The vertical components of the S wave trains recorded on the Eastern Canadian Telemetered Network (ECTN) from 1980 through 1990 have been spectrally analyzed for source, site, and propagation characteristics. The data set comprises some 1033 recordings of 97 earthquakes whose magnitudes range from M ≈ 3 to 6. The epicentral distances range from 15 to 1000 km, with most of the data set recorded at distances from 200 to 800 km. The recorded S wave trains contain the phases S, SmS, Sn, and Lg and are sampled using windows that increase with distance; the acceleration spectra were analyzed from 1.0 to 10 Hz. To separate the source, site, and propagation characteristics, an inversion for the earthquake corner frequencies, low-frequency levels, and average attenuation parameters is alternated with a regression of residuals onto the set of stations and a grid of 14 distances ranging from 25 to 1000 km. The iteration between these two parts of the inversion converges in about 60 steps. The average attenuation parameters obtained from the inversion were Q = 1997 ± 10 and γ = 0.998 ± 0.003. The most pronounced variation from this average attenuation is a marked deamplification of more than a factor of 2 at 63 km and 2 Hz, which shallows with increasing frequency and increasing distance out to 200 km. The site-response spectra obtained for the ECTN stations are generally flat. The source spectral shape assumed in this inversion provides an adequate spectral model for the smaller events (Mo < 3 × 1021 dyne-cm) in the data set, whose Brune stress drops range from 5 to 150 bars. For the five events in the data set with Mo ≧ 1023 dyne-cm, however, the source spectra obtained by regressing the residuals suggest that an ω2 spectrum is an inadequate model for the spectral shape. In particular, the corner frequencies for most of these large events appear to be split, so that the spectra exhibit an intermediate behavior (where |ü(ω)| is roughly proportional to ω).

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Manjunatha, B. J., B. R. Rakshith, K. N. Prakasha e N. V. Sayinath Udupa. "Distance Spectra of Some Double Join Operations of Graphs". International Journal of Mathematics and Mathematical Sciences 2024 (27 maggio 2024): 1–8. http://dx.doi.org/10.1155/2024/2017748.

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In literature, several types of join operations of two graphs based on subdivision graph, Q-graph, R-graph, and total graph have been introduced, and their spectral properties have been studied. In this paper, we introduce a new double join operation based on H1,H2-merged subdivision graph. We compute the spectrum of a special block matrix and then use it to describe the distance spectra of some double join operations of graphs. At last, we give several families of distance equienergetic graphs of diameter 3.

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Kalkan, Erol, e Polat Gülkan. "Site-Dependent Spectra Derived from Ground Motion Records in Turkey". Earthquake Spectra 20, n. 4 (novembre 2004): 1111–38. http://dx.doi.org/10.1193/1.1812555.

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The current spectral shapes in the Turkish Seismic Code ( TSC) are based on broadly described geological conditions, ignoring fault distance or magnitude dependencies on spectral ordinates. To address this deficiency, a data set created from a suite of 112 strong ground motion records from 57 earthquakes that occurred between 1976 and 2003 has been used to develop horizontal attenuation relationships for Turkey. This way it is possible to construct hazard-consistent design spectra for any national seismic region. The results are compared with the site-dependent spectral shapes of the Uniform Building Code ( UBC) and the current TSC. It is shown that corner periods are consistent with those of UBC. TSC yields wider constant spectral acceleration plateau. Design spectra in both of these documents are conservative if the ground motion library that we used in deriving the spectral shapes is taken as representative. The results of this study enable site-distance–magnitude-specific design spectra suitable as a tool both for deterministic (scenario earthquakes) and probabilistic seismic hazard assessments.

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Podemski, Robert, Witold Holubowicz, Claude Berrou e Gerard Battail. "Hamming distance spectra of turbo-codes". Annales Des Télécommunications 50, n. 9-10 (settembre 1995): 790–97. http://dx.doi.org/10.1007/bf02997783.

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Drabløs, Finn. "Symmetric distance measures for mass spectra". Analytica Chimica Acta 201 (1987): 225–39. http://dx.doi.org/10.1016/s0003-2670(00)85340-4.

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Aouchiche, Mustapha, e Pierre Hansen. "Distance spectra of graphs: A survey". Linear Algebra and its Applications 458 (ottobre 2014): 301–86. http://dx.doi.org/10.1016/j.laa.2014.06.010.

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Aalipour, Ghodratollah, Aida Abiad, Zhanar Berikkyzy, Jay Cummings, Jessica De Silva, Wei Gao, Kristin Heysse et al. "On the distance spectra of graphs". Linear Algebra and its Applications 497 (maggio 2016): 66–87. http://dx.doi.org/10.1016/j.laa.2016.02.018.

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Barik, Sasmita, e Gopinath Sahoo. "On the distance spectra of coronas". Linear and Multilinear Algebra 65, n. 8 (27 ottobre 2016): 1617–28. http://dx.doi.org/10.1080/03081087.2016.1249448.

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Pokorný, M., e P. Híc. "DISTANCE SPECTRA OF H-JOIN GRAPHS". Advances and Applications in Discrete Mathematics 17, n. 3 (21 settembre 2016): 305–21. http://dx.doi.org/10.17654/dm017030305.

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33

Taniguchi, M., e Y. Xue. "Hellinger Distance Estimation for Nonregular Spectra". Theory of Probability & Its Applications 69, n. 1 (maggio 2024): 150–60. http://dx.doi.org/10.1137/s0040585x97t991805.

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34

Taniguchi, Masanobu, e Yujie Xue. "Hellinger distance estimation for nonregular spectra". Teoriya Veroyatnostei i ee Primeneniya 69, n. 1 (2024): 188–200. http://dx.doi.org/10.4213/tvp5541.

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Abstract (sommario):

Для стационарного гауссовского процесса выводится расстояние Хеллингера $T(f,g)$ между спектральными плотностями $f$ и $g$. Оценивая $T(f_\theta,f_{\theta+h})$ как $O(h^\alpha)$, мы выводим $1/\alpha$-состоятельную асимптотику оценки максимального правдоподобия для $\theta$ в случае нерегулярных спектральных плотностей. В случае же регулярных спектральных плотностей мы вводим оценку, основанную на минимизации расстояния Хеллингера: $\widehat{\theta}=\operatorname{arg}\min_\theta T(f_\theta,\widehat{g}_n)$, где $\widehat{g}_n$ - непараметрическая оценка спектральной плотности. Мы показываем, что оценка $\widehat\theta$ является асимптотически эффективной и более робастной, чем оценка Уиттла. Представлены также некоторые численные исследования.

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35

Qi, Yingyong, e Bernd Weinberg. "Spectral Slope of Vowels Produced by Tracheoesophageal Speakers". Journal of Speech, Language, and Hearing Research 34, n. 2 (aprile 1991): 243–47. http://dx.doi.org/10.1044/jshr.3402.243.

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Spectra of vowels were analyzed to determine whether differences exist between the spectral slope of vowels produced by tracheoesophageal (TE) speakers and normal speakers and, if so, to quantify such differences. The linear predictive autocorrelation method was used to calculate smoothed spectra and the spectra were normalized with respect to a low frequency component. Comparisons between normalized spectral energy within a selected high frequency range revealed that energy within this frequency range for vowels produced by TE speakers was significantly higher than that produced by normal speakers. A least-square distance matching procedure was used to quantify speaker group differences in the spectral slope of vowels. Average spectra of vowels produced by the normal speakers could be matched to average spectra of vowels produced by the TE speakers by decreasing the spectral slope of their vowels by 2–3 dB/octave.

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36

Usenko, I. A., A. S. Miroshnichenko, S. Danford, D. G. Turner, D. J. Majaess e D. D. Balam. "SPECTROSCOPIC INVESTIGATIONS OF POLARIS FIELD STARS". Odessa Astronomical Publications 36 (4 dicembre 2023): 88–95. http://dx.doi.org/10.18524/1810-4215.2023.36.290534.

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We present the results of an analysis of 28 spectra of 18 Polaris field A–G V stars obtained in 2016–2023. Derived radial velocities and Teff along with distances and reddenings from the Gaia DR3 catalog allowed us to calculate radii of the stars and compare them with calibration relationships “Spectral type – Luminosity” for MS stars. As a result, radii and distances for 9 stars were found overestimated compared to those determined photometrically. Therefore, the DR3 distances are unreliable and should be revisited. According to our data for these stars and their photometric distances, 15 objects belong to a possible old open cluster that is currently dissolved in the Polaris field at a distance ∼70–110pc, while two objects belong to the thick disk, and one belongs to a possible another star group located at a distance of 130 pc.

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37

Zdziarski, Andrzej A. "Variable jet Lorentz factors can explain soft self-absorbed radio spectra of accreting black holes". Monthly Notices of the Royal Astronomical Society: Letters 489, n. 1 (14 agosto 2019): L58—L62. http://dx.doi.org/10.1093/mnrasl/slz127.

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Abstract We study the effect of variable jet bulk Lorentz factors, i.e. either jet acceleration or deceleration, on partially synchrotron self-absorbed radio spectra from cores of radio-loud active galactic nuclei and black hole binaries in the hard state. In about a half of quasars and radio galaxies, their core radio spectra are observed to be soft, i.e. have the spectral index of α < 0. If they are emitted by jets with constant Lorentz factors, that softness implies deposition of large amounts of energy at large distances from the centre. We show here that such soft spectra can be explained without that energetic requirement by emission of jets with the Doppler factor increasing with the distance. This can happen for either jet acceleration or deceleration, depending on the jet viewing angle. We find our model can explain the quiescent radio to X-ray spectra of the BL Lac objects Mrk 421 and Mrk 501.

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38

Huntley, Brian. "Dissimilarity Mapping Between Fossil and Contemporary Pollen Spectra in Europe for the Past 13,000 Years". Quaternary Research 33, n. 3 (maggio 1990): 360–76. http://dx.doi.org/10.1016/0033-5894(90)90062-p.

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AbstractThe degree of analogy between fossil and contemporary pollen spectra in Europe has been investigated using the chord-distance dissimilarity measure. No-analog pollen spectra represent vegetation without a modern analog and hence, by inference, represent macroclimatic conditions different from any occurring in the region today. Such spectra have minimum chord distances that exceed a threshold value assessed using contemporary samples from the same and different vegetation u units. Contoured maps of minimum chord distance portray the changing patterns of analogous and no-analog pollen spectra, and hence vegetation units, since 13,000 yr B.P. No-analog vegetation units have been extensive in some regions for much of the Holocene, persisting as recently as 1000 years ago in many areas. The chord-distance measure has also been used to explore the patterns, extent, and rates of change in European pollen spectra since 13,000 yr B.P. Pollen spectra changed rapidly during late-glacial and early Holocene times and during the last millennium. Paleoclimatic changes have brought about the major changes in the Holocene paleovegetation of Europe. Human impact upon European vegetation has obscured neither the contemporary relationship between pollen spectra and vegetation nor the climatically determined long-term changes of vegetation across the continent since 13,000 yr B.P.

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39

Kaliyaperumal, Sakthidevi, e Kalyani Desikan. "Universal Distance Spectra of Join of Graphs". European Journal of Pure and Applied Mathematics 17, n. 1 (31 gennaio 2024): 462–76. http://dx.doi.org/10.29020/nybg.ejpam.v17i1.5019.

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Consider G a simple connected graph. In this paper, we introduce the Universal distance matrix UD (G). For α, β, γ, δ ∈ R and β ̸= 0, the universal distance matrix UD (G) is defined asUD (G) = αTr (G) + βD(G) + γJ + δI,where Tr (G) is the diagonal matrix whose elements are the vertex transmissions, and D(G) is the distance matrix of G. Here J is the all-ones matrix, and I is the identity matrix. In this paper, we obtain the universal distance spectra of regular graph, join of two regular graphs, joined union of three regular graphs, generalized joined union of n disjoint graphs with one arbitrary graph H. As a consequence, we obtain the eigenvalues of distance matrix, distance Laplacian matrix, distance signless Laplacian matrix, generalized distance matrix, distance Seidal matrix and distance matrices of complementary graphs.

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40

Sabetta, Fabio, e Antonio Pugliese. "Estimation of response spectra and simulation of nonstationary earthquake ground motions". Bulletin of the Seismological Society of America 86, n. 2 (1 aprile 1996): 337–52. http://dx.doi.org/10.1785/bssa0860020337.

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Abstract Italian strong-motion data were used to study the attenuation of response spectra and to simulate artificial accelerograms as a function of magnitude, distance, and site geology. The database has already been utilized for the study of the attenuation of peak ground acceleration (PGA) and velocity and consists of 95 accelerograms from 17 earthquakes of magnitudes ranging from 4.6 to 6.8. Using multiple regressions, we developed empirical predictive equations for the vertical and horizontal components of response spectra corresponding to 14 frequencies ranging from 0.25 to 25 Hz. Predictive equations, aimed at the ground-motion simulation, were also estimated for time-dependent frequency parameters, strong ground motion duration, and Arias intensity. The shape of the predicted spectra is strongly dependent on magnitude and nearly independent of distance. Alluvium sites show an amplification effect, with respect to stiff sites, in different frequency ranges according to the thickness of the soil deposit. The vertical/horizontal spectral ratio in far field varies, with magnitude and frequency, from 0.35 to 0.85. The resulting response spectra are compared with the predictions of some recent attenuation relationships and with those proposed by the Eurocode EC8. The simulation of nonstationary strong ground motions is achieved through an empirical method where time and frequency features of the motion are represented through the physical spectrum, extending the spectral moments theory to the nonstationary case. The simulated time histories fit the recorded accelerograms in terms of several ground-motion amplitude measures, such as peak acceleration, peak velocity, Fourier spectra, and response spectra. The principal advantage of the proposed method consists in correlating the simulation parameters with earthquake magnitude, source distance, and soil conditions.

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41

Schmutz, Werner, e Ian D. Howarth. "The Distance to HD 50896 (EZ CMA)". Symposium - International Astronomical Union 143 (1991): 639. http://dx.doi.org/10.1017/s0074180900046015.

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The WN5 star HD 50896 lies in the same sightline as the open cluster Cr 121. In order to investigate the possibility of cluster membership, we observed the interstellar Na D lines in the spectra of HD 50896 (=EZ CMa, =WR6) and stars in its neighbourhood (on the plane of the sky) at high spectral resolution (R=80,000 and 105,000). The observations were obtained with the 1.4-m coudé auxiliary telescope and the coudé echelle spectrograph of the European Southern Observatory.From the strengths and velocity structure of the interstellar features it is immediately clear that HD 50896 is not a member of Cr 121; rather, it is a background object. A comparison with spectra of other background stars shows that the line of sight towards HD 50896 is very similar to those of HD 51854 (B1 V) and HD 50562 (B3 III). From intermediate-band and Hβ photometry the distances to these two B stars are 1.75 kpc and 1.95 kpc, respectively. The most red-shifted absorption component in the spectrum of HD 50896 is displaced only slightly more than that of HD 51854, and a little less than that of HD 50562. We conclude that the the most probable distance to HD 50896 is 1.8 kpc.

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42

Catral, Minerva, Lorenzo Ciardo, Leslie Hogben e Carolyn Reinhart. "Spectra of products of digraphs". Electronic Journal of Linear Algebra 36, n. 36 (1 dicembre 2020): 744–63. http://dx.doi.org/10.13001/ela.2020.5243.

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Abstract (sommario):

A unified approach to the determination of eigenvalues and eigenvectors of specific matrices associated with directed graphs is presented. Matrices studied include the new distance matrix, with natural extensions to the distance Laplacian and distance signless Laplacian, in addition to the new adjacency matrix, with natural extensions to the Laplacian and signless Laplacian. Various sums of Kronecker products of nonnegative matrices are introduced to model the Cartesian and lexicographic products of digraphs. The Jordan canonical form is applied extensively to the analysis of spectra and eigenvectors. The analysis shows that Cartesian products provide a method for building infinite families of transmission regular digraphs with few distinct distance eigenvalues.

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43

Good, S. W., O. K. Rantala, A. S. M. Jylhä, C. H. K. Chen, C. Möstl e E. K. J. Kilpua. "Turbulence Properties of Interplanetary Coronal Mass Ejections in the Inner Heliosphere: Dependence on Proton Beta and Flux Rope Structure". Astrophysical Journal Letters 956, n. 1 (1 ottobre 2023): L30. http://dx.doi.org/10.3847/2041-8213/acfd1c.

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Abstract Interplanetary coronal mass ejections (ICMEs) have low proton beta across a broad range of heliocentric distances and a magnetic flux rope structure at large scales, making them a unique environment for studying solar wind fluctuations. Power spectra of magnetic field fluctuations in 28 ICMEs observed between 0.25 and 0.95 au by Solar Orbiter and Parker Solar Probe have been examined. At large scales, the spectra were dominated by power contained in the flux ropes. Subtraction of the background flux rope fields increased the mean spectral index from −5/3 to −3/2 at kd i ≤ 10−3. Rope subtraction also revealed shorter correlation lengths in the magnetic field. The spectral index was typically near −5/3 in the inertial range at all radial distances regardless of rope subtraction and steepened to values consistently below −3 with transition to kinetic scales. The high-frequency break point terminating the inertial range evolved approximately linearly with radial distance and was closer in scale to the proton inertial length than the proton gyroscale, as expected for plasma at low proton beta. Magnetic compressibility at inertial scales did not show any significant correlation with radial distance, in contrast to the solar wind generally. In ICMEs, the distinctive spectral properties at injection scales appear mostly determined by the global flux rope structure while transition-kinetic properties are more influenced by the low proton beta; the intervening inertial range appears independent of both ICME features, indicative of a system-independent scaling of the turbulence.

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44

Varghese, Renny P., e D. Susha. "Vertex Distance Complement Spectra of Some Graphs". Annals of Pure and Applied Mathematics 16, n. 1 (1 gennaio 2018): 69–80. http://dx.doi.org/10.22457/apam.v16n1a9.

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45

Nath, Milan, e Somnath Paul. "On the distance Laplacian spectra of graphs". Linear Algebra and its Applications 460 (novembre 2014): 97–110. http://dx.doi.org/10.1016/j.laa.2014.07.025.

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46

Koolen, Jack H., Sakander Hayat e Quaid Iqbal. "Hypercubes are determined by their distance spectra". Linear Algebra and its Applications 505 (settembre 2016): 97–108. http://dx.doi.org/10.1016/j.laa.2016.04.036.

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47

Lu, Lu, Qiongxiang Huang e Zhenzhen Lou. "On the distance spectra of threshold graphs". Linear Algebra and its Applications 553 (settembre 2018): 223–37. http://dx.doi.org/10.1016/j.laa.2018.05.014.

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48

Lin, Huiqiu, e Yuke Zhang. "Extremal problems on distance spectra of graphs". Discrete Applied Mathematics 289 (gennaio 2021): 139–47. http://dx.doi.org/10.1016/j.dam.2020.09.023.

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49

Harmsen, Stephen C. "Estimating the diminution of shear-wave amplitude with distance: Application to the Los Angeles, California, urban area". Bulletin of the Seismological Society of America 87, n. 4 (1 agosto 1997): 888–903. http://dx.doi.org/10.1785/bssa0870040888.

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Abstract (sommario):

Abstract The rate of decay with distance of shear-wave amplitude, computed from 20-sec S-wave spectra, is determined from TERRAscope records of small earthquakes in the greater Los Angeles area. Piecewise log-linear interpolation functions and traditional diminution functions are used to fit spectral decay to a maximum distance of 150 km. Simultaneously, isotropic source and receiver terms are determined. Separate branches of the spectral decay function are found for two categories of source depth: greater than 10 km and less than 10 km. In the hypocentral distance range of 20 to 150 km and in the frequency range of 0.5 to 8.0 Hz, an important result of the investigation is that the horizontal-component decay rate associated with deeper-crustal sources is generally greater than that associated with shallower sources and is greater than that which is estimated using more traditional models of spectral decay with distance. The same behavior generally holds for vertical-component spectra. The variation in apparent attenuation rate with source depth should affect seismic-hazard estimates associated with the rupture of blind thrust faults in the Los Angeles basin and vicinity. The results of the inversions suggest that interpolation function representations of spectral decay are sensitive to perturbations of S-wave amplitude due to crustal reflectors, such as post-critical S-wave arrivals from mid-crustal to deep-crustal velocity interfaces.

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50

Frizzarin, Maria, Isobel Claire Gormley, Alessandro Casa e Sinéad McParland. "Selecting Milk Spectra to Develop Equations to Predict Milk Technological Traits". Foods 10, n. 12 (11 dicembre 2021): 3084. http://dx.doi.org/10.3390/foods10123084.

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Abstract (sommario):

Including all available data when developing equations to relate midinfrared spectra to a phenotype may be suboptimal for poorly represented spectra. Here, an alternative local changepoint approach was developed to predict six milk technological traits from midinfrared spectra. Neighbours were objectively identified for each predictand as those most similar to the predictand using the Mahalanobis distances between the spectral principal components, and subsequently used in partial least square regression (PLSR) analyses. The performance of the local changepoint approach was compared to that of PLSR using all spectra (global PLSR) and another LOCAL approach, whereby a fixed number of neighbours was used in the prediction according to the correlation between the predictand and the available spectra. Global PLSR had the lowest RMSEV for five traits. The local changepoint approach had the lowest RMSEV for one trait; however, it outperformed the LOCAL approach for four traits. When the 5% of the spectra with the greatest Mahalanobis distance from the centre of the global principal component space were analysed, the local changepoint approach outperformed the global PLSR and the LOCAL approach in two and five traits, respectively. The objective selection of neighbours improved the prediction performance compared to utilising a fixed number of neighbours; however, it generally did not outperform the global PLSR.

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