The quantitative analysis of iron ore by laser-induced breakdown spectroscopy (LIBS) is usually complicated due to nonlinear self-absorption and matrix effects. To overcome this challenge, a hybrid ...sparse partial least squares (SPLS) and least-squares support vector machine (LS-SVM) model was proposed to analyze the content of total iron (TFe) and oxides SiO
2
, Al
2
O
3
, CaO, and MgO in iron ore. In this study, 24 samples were used for calibration and 12 for prediction. Sparse partial least squares was used for variable selection and establishing the multilinear regression model between spectral data and concentrations; LS-SVM was used to fit the residual errors of the SPLS regression model to compensate for the nonlinear effects. The model parameters were determined by using the tenfold cross-validation (CV) method. With the hybrid model, the root-mean-square-error of prediction (RMSEP) values of TFe, SiO
2
, Al
2
O
3
, CaO, and MgO were 0.6242, 0.3569, 0.0456, 0.0962, and 0.2157 wt%, respectively. The results showed that the hybrid model yielded better performance than only the conventional SPLS or LS-SVM model. This study demonstrated that the hybrid model is a competitive data processing method for iron ore analysis using LIBS.
A hybrid sparse partial least squares and least-squares support vector machine model was proposed to improve the accuracy of iron ore analysis using LIBS.
The microstructure, texture and mechanical properties evolution of the extruded fine-grained Mg-(1, 5) Y (wt%) alloy sheets were investigated during annealing. The as-extruded sheets exhibited a ...fully dynamic recrystallized (DRXed) microstructure consisting of uniform and fine equiaxed grains (5.7–8.7 µm) and a small amount of YH2 second phase particles. Both sheets exhibited significant thermal stability at 300 °C annealing and remarkable grain growth at temperatures higher than 400 °C. The measured grain growth activation energy (Q) of Mg-1Y at all temperatures tested was 91 ± 3 kJ/mol, suggesting that the growth was controlled by grain boundary diffusion. Meanwhile, for Mg-5Y alloy at lower temperatures (300–400 °C), the Q value (59 kJ/mol) indicated that the grain growth was controlled by grain boundary diffusion while the Q value (175 kJ/mol) at higher temperatures (400–450 °C) implied that lattice self-diffusion controlled the process. A representative rare-earth texture was present for both sheets in the as-extruded condition, and remarkable basal texture weakening was observed with the grain growth during each isothermal annealing process. The texture weakening can be ascribed to the preferential growth of non-basal oriented grains based on the EBSD analysis, which was likely related to the segregation of Y atoms at grain boundaries. The microhardness and grain size relationship can be described well by the Hall-Petch relation for all the annealed sheets, while the yield stress was not the case indicating that the macroscopic strength was more sensitive to the texture than the localized microhardness.
The plastic anisotropy in terms of tensile mechanical property, Lankford coefficient (r), and microstructure evolution of as-extruded Mg-1Y (wt%) and Mg-5Y (wt%) sheets along the extrusion direction ...(ED), transverse direction (TD), and diagonal direction (DD) were investigated in detail at temperatures between 25℃ (RT) and 300℃. The sheets exhibited anisotropic deformation behavior at lower temperatures, and nearly isotropic for Mg-5Y at 300℃ in these three directions. For both sheets, the ultimate tensile strength anisotropy (UA) and elongation anisotropy (EA) was not sensitive to the temperature, while the yield strength anisotropy (YA) decreased significantly from 49.1% (Mg-1Y) and 40.2% (Mg-5Y) at RT to 7.2% and 2.7% at 300℃, respectively. The r values of Mg-1Y in all directions first increased from 0.66-1.4 (RT) to 0.81–1.98 (200℃) then decreased to 0.67–1.56 (300℃), while those of Mg-5Y decreased from 1.04-2.05 (RT) to 1.18–1.35 (300℃) with increasing temperature. Few twins were observed in Mg-5Y after tension at RT while large amounts of twins occurred in Mg-1Y. The huge reduction of twins and the weakened basal texture are believed to increase the r value from 0.66 (Mg-1Y) to 1.04 (Mg-5Y) at RT. At 300℃, dynamic recrystallized (DRX) grains appeared in Mg-1Y while only a few DRX grains showed up in the vicinity of grain boundaries in Mg-5Y, which may be closely related to grain boundary segregation of the yttrium atoms.
Correction for 'Accuracy improvement of iron ore analysis using laser-induced breakdown spectroscopy with a hybrid sparse partial least squares and least-squares support vector machine model' by Y. ...M. Guo
et al.
,
J. Anal. At. Spectrom.
, 2018,
33
, 1330-1335, DOI: 10.1039/C8JA00119G.
A new approach to polymer identification by laser-induced breakdown spectroscopy (LIBS) with adjusting spectral weightings (ASW) was developed in this work aiming at improving the identification ...accuracy. This approach has been achieved through increasing the intensities of specific characteristic spectral lines which are important to polymer identification but difficult to be excited. Using the ASW method, the identification accuracies of all 11 polymers were increased to nearly 100%, while the accuracies of PE, PU, PP and PC were only 98%, 74%, 90% and 98%, respectively, without using the ASW method.
A modified algorithm of background removal based on wavelet transform was developed for spectrum correction in laser-induced breakdown spectroscopy (LIBS). The optimal type of wavelet function, ...decomposition level and scaling factor γ were determined by the root-mean-square error of calibration (RMSEC) of the univariate regression model of the analysis element, which is considered as the optimization criteria. After background removal by this modified algorithm with RMSEC, the root-mean-square error of cross-validation (RMSECV) and the average relative error (ARE) criteria, the accuracy of quantitative analysis on chromium (Cr), vanadium (V), cuprum (Cu), and manganese (Mn) in the low alloy steel was all improved significantly. The results demonstrated that the algorithm developed is an effective pretreatment method in LIBS to significantly improve the accuracy in the quantitative analysis.
The bottom-up fabrication of molecular nanodevices will require precise (photo)-control over self-assembled interfacial structures. Here, the self-assembly and photopolymerization behaviors of six ...diacetylenic acid derivatives on highly oriented pyrolytic graphite (HOPG) surfaces are studied by using scanning tunneling microscope (STM). The van der Waals interaction among alkyl chains is the predominant driving force for determining the varied assembly structure. Diacetylenic acid derivatives with the diacetylene moiety directly connected to the carboxyl group (2,4-heptadecadiynoic acid (C
17
H
26
O
2
), 2,4-nonadecadiynoic acid (C
19
H
30
O
2
) and 2,4-heneicosadiynoic acid (C
21
H
34
O
2
)) assemble to form surface monolayers with lamella-like structures where the alkyl chains interdigitate. Moreover, diacetylenic acid derivatives with the diacetylene group located in the middle of the side chains and far from the carboxyl group (10,12-tricosadiynoic acid (C
23
H
38
O
2
), 10,12-pentacosadiynoic acid (C
25
H
42
O
2
) and 10,12-heptacosadiynoic acid (C
27
H
46
O
2
)) tend to assemble into paralleled structures with the alkyl chains adopting a tail-to-tail assembly mode. This work thus elucidates in detail the structure-function relationships for photo-modifiable self-assembled interfacial nanostructures based on diacetylenic acid.
The effect of UV illumination time on the polymerization efficiency and the structural change of DA-25.
In this paper, a solar hybrid one-rotor two-stage desiccant cooling and heating system has been numerically analyzed. The system was made up of a one-rotor two-stage desiccant cooling unit, with ...design cooling capacity for 5 kW, and a solar collector array of 15 m2. Performance model of the system was created in TRNSYS simulation studio. Firstly, base case performance models were programmed according to the configuration of the installed solar desiccant system and verified by the experimental data. Secondly, the year-round performance about the system was simulated. Finally, we optimized the parameters of the system, including the solar collector area, the ratio between fresh air and return air, and the heat exchanger efficiency. Numerical results agree with the experimental ones. The simulation results showed that about 60% of the humidity load can be totally handled by the one-rotor two-stage desiccant cooling unit, and about 40% of the heating load can be handled by solar energy.
•Performance model of a solar cooling/heating system was created in TRNSYS studio.•Performance analysis of annual data shows that the solar system can operate well.•Evacuated tube solar air collector was applied in a developed air-conditioning unit.
Stripe rust, caused by Puccinia striiformis f. tritici, is one of the most destructive diseases of wheat in the world. The Sichuan Basin is one of the most important regions of wheat production and ...stripe rust epidemics in China. Stripe rust resistance gene Yr26 (the same gene as Yr24) has been widely used in wheat breeding programs and in many cultivars grown in this region since the gene was discovered in the early 1990s. Virulence to Yr26 has increased in frequency since its first detection in 2008. The objective of this study was to assess the vulnerability of the wheat cultivars and breeding lines in the Sichuan Basin to Yr26-virulent races. In total, 85 wheat accessions were tested with Yr26-avirulent races CYR32, CYR33, and Su11-4 and two Yr26-virulent races, V26/CM42 and V26/Gui22. DNA markers for Yr26 were used to determine the presence and absence of Yr26 in the wheat accessions. Of the 85 wheat accessions, only 5 were resistant and 19 susceptible to all races tested, and the remaining 61 were resistant to at least one or more races tested in seedling stage. In all, 65 (76.5%) accessions were susceptible to the emerging Yr26-virulent race V26/Gui22. In field tests, susceptible accessions increased from 31.8% in a nursery inoculated with predominant and Yr26-avirulent races to 61.2% in the nursery inoculated with the predominant races mixed with V26/Gui22. Based on the results of the molecular marker and race tests, 33 (38.8%) accessions were determined to have Yr26, showing that the Yr26 virulence is a major threat to wheat production in the Sichuan Basin and potentially in other regions of China.
This study aimed to investigate to the effects of dietary CP levels and protease supplementation on growth performance, carcass traits, meat quality, nutrients utilization, and standardized ileal ...digestibility of amino acid in Pekin ducks fed a complex diet. A total of 960 14-day-old male ducks were weighed and randomly allotted to a 2 × 5 factorial arrangement of 10 treatments with 6 replicate pens per treatment and 16 ducks per pen fed to 49 D of age. Experimental factors included five dietary CP levels ranging from 13.5 to 17.5% and with or without protease (200 mg/kg) supplementation. Between day 28 to 34, the digestible and metabolizable trials were performed. Significant CP × protease interactions (P < 0.05) on breast meat yield, DM, energy and nitrogen utilization, as well as standardized ileal digestibility values of 7 amino acids were observed. Regardless of protease supplementation, ducks fed 13.5, 14.5, and 15.5% CP had a poorer (P < 0.05) growth performance and breast meat yield than ducks fed with 16.5 and 17.5% CP. Ducks fed 13.5% CP had a positive effect (P < 0.05) on meat quality, dietary DM, energy and nitrogen utilization as well as standardized ileal digestibility of amino acids. Protease supplementation increased (P < 0.05) DM and phosphorus retention and decreased (P < 0.05) shear force of breast meat, regardless of CP level; when CP = 14.5%, protease significantly increased (P < 0.05) breast muscle yield. The optimal CP requirement without or with protease supplementation for BWG and FI were 17.02 or 16.53% and 16.64 or 16.75%, respectively, based on linear broken-line regression.
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