236 research outputs found
Contrasting effects of maize straw and its biochar on aggregation and soil organic matter stabilization
No full textBackground and aims: Crop straw and it derived biochar are both promising to improve soil fertility and structure. However, the contribution of these amendments to microbial biomass and aggregate formation, as well as carbon (C) and nitrogen (N) stabilization within aggregates is lacking. Methods: Maize straw that was labelled with 13C and 15N or its biochar (produced at 400 °C) were added to soil to quantify the incorporation of C and N into dissolved organic matter, microbial biomass, and aggregates throughout lab incubation. Results: After 20 days of incubation, 48% of microbial biomass C (MBC) and 18% of microbial biomass N (MBN) was derived from straw. In contrast, biochar contributed 4% to the MBC pool, with only a trace contribution to MBN. These contributions were reflected in the dissolved organic matter C and N pools. Soil aggregation (mean weight diameter) was 14% greater amended with straw than with biochar within the first 100 days, but without differences thereafter. Because the straw-derived binding agents for aggregation are short-lived, their effects on aggregate formation disappeared after 100 days resulting in a similar impact as that found in soil with biochar. Larger amounts of straw-derived C and N were occluded within aggregates compared to biochar. Conclusion: The amendments of soil with straw and biochar affected microbial processing, reflected in the uptake of C and N into microbial biomass, dissolved organic matter and aggregates. We conclude that straw has a short-term effect on aggregation, while biochar has limited impact on aggregation.Full Tex
Statistical Comparisons of Multiple Classifiers
No full textThis paper discusses the issue of comparing multiple classifiers, applied to the same test dataset of a classification problem. Assume that the output is 0 if a classifier correctly classifies a test feature point and the output is 1 otherwise.Then all the outputs from a given classifier constitute a sample of 0 and 1, and all the samples are correlated. From these dependent samples, we use Cochran's Q statistic, as an overall test statistic, to detect whether or not the error rates of the classifiersare significantly different. When the null hypothesis that the error rates are equal is rejected, a thorough analysis of the nature of the error rates, such as the ranking of the error rates, is undertaken. For this purpose, we employ the Scheffe and Bonferroni multiple comparison procedures, based on dependent samples. We also use examples to demonstrate how to make these statistical comparisons.Cheng, Xiuzhen; Chen, Dechang. (2001). Statistical Comparisons of Multiple Classifiers. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/215473
Recommended from our members
Electro-optic polymer-based monolithic waveguide devices with multi-functions of amplification switching and modulation
No full texttextElectro-optic (EO) polymer materials have become a promising option for
high-performance integrated optics due to their high nonlinearity, small velocity
mismatch for traveling wave devices, and flexible monolithic integrated capability on
any interested substrates. Based on waveguides fabricated with EO polymers, our
research objectives were (1) to design and fabricate amplifiers, switches, and
modulators and (2) to investigate the possibility of integrating these devices into a
monolithic module.
By co-doping rare-earth ions and EO chromophores into photolime gel, a
well-known backbone for holographic materials, we present here a dual-functional
planar waveguide demonstrating the capability of amplification and modulation.
Complete device-fabrication processes, including wafer preparing, polymer
coating and curing, adhesion enhancing of film interfaces, waveguide RIE etching,
electrode patterning and plating, wafer dicing, waveguide polishing, and wire
bonding, have been investigated in depth. All these techniques can be applied to make
not only electro-optic polymeric devices, but thermal-optical polymeric devices as
well. Straight channel array, Y-coupler array, and X-junction have been demonstrated
successfully, all made from polyimides.
With a thermal-setting EO polymer PU-FTC, both corona poling and contact
poling were investigated. A novel domain-inversion poling technique was developed.
We demonstrated an electro-optic modulator based on a 1x2 Y-branch directional
waveguide coupler. The symmetric geometry of this coupler provides the modulator
with the unique characteristics of an intrinsic 3dB operating point and two
complementary output ends. The design, fabrication, and testing of the modulator are
discussed in the dissertation.
A highly linearized Y-coupler modulator is presented lastly. The high linearity
is achieved by suppressing its IMD3 with the ∆β−inversion method. The operation
principle of the device is analyzed here. Substantial suppression was achieved for a
∆β−inverted modulator in a wide dynamic range up to 70% optical modulation depth.
An IMD3 suppression of 47.29dB was observed for this modulator, as opposed to a
conventional one.Electrical and Computer Engineerin
The 1126 Ma volcanic event in the Dechang Area, SW Yangtze Block, and its significance
No full textTraditionally, the strata of the Luonie Valley, Dechang County, SW Sichuan, China, are considered to contain a suite of felsic volcanic rocks (the Huili Group) that erupted after c. 1050 Ma. However, we report here new age constraints, elemental and Lu–Hf isotope geochemistry for a different suite of older basaltic agglomerate lava, basaltic tuff lava and basalt from the same area, which we name the Luonie Formation. New dating results show that the basaltic volcanic suite of the upper part of the Luonie Formation formed at 1126.1 ± 9.9 Ma, significantly earlier than deposition of the Huili Group, but comparable in age to the 1142 ± 16 Ma Laowushan Formation in central Yunnan Province. Granite intrusion into the Luonie Formation dated 1050.7 ± 12.7 Ma provides crucial supporting evidence for this earlier depositional age. We also report a maximum sedimentary age of c. 1158 Ma for the underlying arkose, implying stratigraphic conformity with the basaltic volcanic rock suite.
The ϵHf(t) values of the basaltic volcanic rocks are mainly positive, indicating that the rocks are mainly derived from the depleted mantle and slightly stained by crustal materials. The characteristics of P*, Nb* and Zr* anomalies also support this view. The distribution patterns of trace and rare earth elements indicate that the basaltic volcanic rocks formed in an extensional setting. The Zr/4–Y–2Nb and Th–Nb/16–Zr/117 discrimination diagrams also provide evidence for this understanding. Lithofacies analysis shows that basaltic volcanic wrocks with the characteristics of both continental and marine facies should be formed in a littoral–neritic environment. We propose here that the evidence is consistent with a phase of continental extension that preceded the convergence of the SW Yangtze Block to form part of Rodinia
Set analysis of coincident errors and its applications for combining classifiers
No full textAlthough addressed in many papers, classifier dependency is still not well defined. Continuously being described by variety of statistical models from conditional probability to diversity measures, dependency among classifier out-puts was recently shown to have a crucial impact on the performance of multi-ple classifier system. However, individual classifier performances still represent competitive and simple information clearly related to the performance of the combined system. In this work we show that all the measures related to classi-fier outputs can be reformulated to represent just different forms of the same in-formation of error coincidences. Applying set analysis for the representation and description of error coincidences we define collection of classifier sets de-composed into two complementary types of coincidence levels. Furthermore we illustrate a high flexibility of using the coincidence levels, which supported be a simple algebra cover many established dependency measures including combin-ing error in case of majority voting. Moreover we show that in the sets-collection representation of error coincidences a specific inclusion relation re-sults in a quicker and more effective handling of dependency information under different complexity conditions. In the experimental section we examine rela-tions of the introduced error coincidence levels with majority voting combiner using real datasets and classifiers and indicate further potential applications of the presented concepts
An angle-based bi-objective optimization algorithm for redundancy allocation in presence of interval uncertainty
No full textThe file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Uncertainty is a practical issue in system design optimization because some characteristics of components, such as reliability and cost, cannot be determined precisely in many situations. Considering the imprecise characteristics of components, few works have focused on the multi-objective optimization for the redundancy allocation due to the challenges of comparing multi intervals. To tackle the issue, a novel angle-based bi-objective redundancy allocation algorithm is proposed in this study, introducing three original contributions: 1) An angle-based interval crowding distance (ICA) is especially designed for effective performance and reduced computational time; 2) Two techniques are applied to tackle the problem: An elite selection for mutation is presented for generating better offsprings; A penalty-guided constraint handling technique is introduced for converting the problem into an unconstrained one. 3) Since a set of optimal solutions is obtained by the proposed method and no preference on uncertainties is provided, this paper proposes a novel knee interval method to help DMs make a decision. To be specific, the proposed ICA can describe the distribution of the whole population intuitively and effectively, considering not only the angle between two compared individuals but also the angle range of the interval values. The computational results from two typical experiments demonstrate that the proposed algorithm is more efficient than other state-of-the-art algorithms, generating Pareto sets with less repeating individuals, stronger convergence, wider distribution, less imprecision, and reduced computational time
Zircon Alteration as a Proxy for Rare Earth Element Mineralization Processes in Carbonatite-Nordmarkite Complexes of the Mianning-Dechang Rare Earth Element Belt, China
No full textZircon is a common accessory mineral in igneous rocks, including carbonatite-nordmarkite complexes. Zircons can record radiation damage and hydrothermal alteration through changes in oxygen isotope values, crystal structures, and geochemical and petrographic characteristics. The Mianning-Dechang rare earth element (REE) belt in China hosts 12 carbonatite-nordmarkite complexes and related Cenozoic REE deposits. We investigated zircons from these nordmarkites to understand the formation of the REE deposits. Three types of zircon from fresh and altered nordmarkite were identified. Type I zircons are unaltered, type II zircons experienced fenitization associated with hydrothermal alteration, and type III zircons were strongly affected by ore-forming fluids and REE mineralization. Type III zircons have higher Th, U, light REE, and REE contents (43,100, 52,000, 7,420, and 9,000 ppm, respectively) than type I zircons (1,450, 8,100, 265, and 1,130 ppm, respectively) and type II zircons (1,370, 19,520, 334, and 1,210 ppm, respectively). Petrographic observations, Raman spectra, and geochemical characteristics show that from type I to III zircons the crystals experienced increased radiation damage, hydrothermal alteration, and metasomatism by ore-forming fluids and show a transition to hydrothermal zircon. Type I, type II, and type III zircons have D-alpha(T) (alpha dose) values of 0.6 to 29.5, 7.1 to 207, and 64 to 687 alpha-decay events/mg, with averages of 12.7, 87.36, and 144 alpha-decay events/mg, respectively. In general, the radiation damage trend shows that the Raman frequency is similar to 995 cm(-1), even at high levels of radiation damage. However, the Raman frequency of type III zircon can reach 991 cm(-1) with a line width of 28 cm-1, indicating type III zircons have a lower degree of crystallinity than type I and II zircons as a result of the effects of additional alteration by ore-forming fluids rich in Th and U. The involvement of ore-forming fluids and influx of meteoric water into the magmatic water is evident from the delta O-18 values of type I, II, and III zircons of 5.15 to 8.65 parts per thousand, 1.50 to 6.24 parts per thousand, and 1.92 to 5.86 parts per thousand, respectively. U-Pb dating of type I zircons yields similar ages within a given deposit. Type II and III zircons could not be dated for the formation ages of REE deposits due to their high degree of alteration, abundant mineral inclusions, and variable common and radiogenic Pb contents. Given the chemical composition of the hydrothermal fluids and REE minerals, the geochemical characteristics of type III zircons suggest that highly evolved ore-forming fluids rich in Na, K, Ca, Cl, SO4, F, REEs, Th, U, Zr, Hf, and Pb facilitated zircon alteration. It is therefore concluded that the changes in zircon geochemistry and crystal characteristics could serve as a proxy for carbonatite-nordmarkite-related REE mineralization processes and as an indicator for REE exploration. A schematic model of the formation of type I, II, and III zircons and REE mineralization stages in the Mianning-Dechang REE deposits is presented
Exploiting bifunctional 3D-Printed geopolymers for efficient cesium removal and immobilization: An approach for hazardous waste management
No full text3D-printed geopolymer lattices (3DGPLs) have recently been considered as promising candidates for hazardous waste management due to their low cost, porous nature, and excellent environmental stability. However, the ion adsorption capacity influenced by usage conditions such as multi-ion systems and radiation remains largely unexplored. Furthermore, effective strategies to immobilize adsorbed ions for long-term disposal are still lacking. This work tackles these questions by studying the Cs+ adsorption and immobilization properties of 3DGPLs in the presence of competing ions and gamma-ray radiation. Our results reveal the inhibitory intensity of Cs+ adsorption capacity by five common metal cations in seawater, ranked in the following order: Na+ > K+ > Ca2+ > Mg2+ > Sr2+. After exposure to different doses of gamma-ray radiation, the Cs+ adsorption capacity of 3DGPLs shows no significant change, demonstrating their outstanding radiation resistance. By encapsulating the Cs-containing 3DGPL with a homologous GP coating, the Cs+ immobilization rate reaches 98.545% after leaching in NaCl solution at 60 degrees C for 5 days. The already-high Cs+ immobilization rate can be further increased to 99.228% by sintering treatment due to the densification effect. This study not only provides microscopic insights into the adsorption of hazardous ions by 3DGPLs under usage conditions, but also offers a feasible approach to prevent the leakage of loaded ions through GP coating technology
- …
