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11.
Taghi M. Khoshgoftaar Kehan Gao Amri Napolitano Randall Wald 《Information Systems Frontiers》2014,16(5):801-822
Two important problems which can affect the performance of classification models are high-dimensionality (an overabundance of independent features in the dataset) and imbalanced data (a skewed class distribution which creates at least one class with many fewer instances than other classes). To resolve these problems concurrently, we propose an iterative feature selection approach, which repeated applies data sampling (in order to address class imbalance) followed by feature selection (in order to address high-dimensionality), and finally we perform an aggregation step which combines the ranked feature lists from the separate iterations of sampling. This approach is designed to find a ranked feature list which is particularly effective on the more balanced dataset resulting from sampling while minimizing the risk of losing data through the sampling step and missing important features. To demonstrate this technique, we employ 18 different feature selection algorithms and Random Undersampling with two post-sampling class distributions. We also investigate the use of sampling and feature selection without the iterative step (e.g., using the ranked list from a single iteration, rather than combining the lists from multiple iterations), and compare these results from the version which uses iteration. Our study is carried out using three groups of datasets with different levels of class balance, all of which were collected from a real-world software system. All of our experiments use four different learners and one feature subset size. We find that our proposed iterative feature selection approach outperforms the non-iterative approach. 相似文献
12.
The content and positional distribution of CLA in TAG fractions of lamb tissues was examined with either preformed CLA or
the linoleic acid precursor of CLA in the diet as experimental treatments. The CLA content of phospholipid (PL) from these
tissues was also examined. Thirteen lambs were randomized to the following dietary treatments: (i) control diet (no supplement);
(ii) CLA supplementation (0.33 g d−1 for 21 d prior to weaning) to milk-replacer of pre-ruminating lambs, or (iii) feeding linoleic acid-rich oil (6% safflower
oil on a dry matter basis) to weaned ruminating lambs. At slaughter, tissue samples were procured from diaphragm, rib muscle,
and subcutaneous (SC) adipose tissue. Safflower oil supplementation in the diet resulted in an increase in CLA content of
the TAG from diaphragm, rib muscle, and SC adipose tissue by about threefold (P<0.05) on a mol% basis. CLA was localized to the sn-1/3 positions of TAG. Animals that received pre-formed CLA, however, had increased proportions of CLA at the sn-2 position of TAG from SC adipose tissue, suggesting that there were tissue-specific dietary effects and possible age-related
effects on the mode of FA incorporation into TAG. Safflower oil supplementation in the diet had no effect on the CLA content
of PL from diaphragm, rib muscle, and SC adipose tissue, suggesting that CLA was preferentially incorporated into the TAG
of these tissues. 相似文献
13.
A multiple sequence alignment algorithm is described that usesa dynamic programming-based pattern construction method to aligna set of homologous sequences based on their common patternof conserved sequence elements. This pattern-induced multi-sequencealignment (PUMA) algorithm can employ secondary-structure dependentgap penalties for use in comparative modelling of new sequenceswhen the three-dimensional structure of one or more membersof the same family is known. We show that the use of secondarystructure information can significantly improve the accuracyof aligning structure boundaries in a set of homologous sequenceseven when the structure of only one member of the family isknown 相似文献
14.
Xinyi Xu Randall E. Youngman Saurabh Kapoor Ashutosh Goel 《Journal of the American Ceramic Society》2021,104(10):5030-5049
If the direct feed approach to vitrify the Hanford's tank waste is implemented, the low activity waste (LAW) will comprise higher concentrations of alkali/alkaline-earth sulfates than expected under the previously proposed vitrification scheme. To ensure a minimal impact of higher sulfate concentrations on the downstream operations and overall cost of vitrification, advanced glass formulations with enhanced sulfate loadings (solubility) are needed. While, the current sulfate solubility predictive models have been successful in designing LAW glasses with sulfate loadings <2 wt.%, it will be difficult for them to design glass compositions with enhanced loadings due to our limited understanding of the fundamental science governing these processes. In this pursuit, this article unearths the underlying compositional and structural drivers controlling the sulfate solubility in model LAW glasses. It has been shown that the preferentially removes non-framework cations from the modifier sites in the silicate network, thus, leading to the polymerization in the glass network via the formation of ring-structured borosilicate units. Furthermore, though the sulfate solubility slightly decreases with increasing Li+/Na+ in the glasses, the prefers to be charge compensated by Na+, as it is easier for to break Na–O bonds instead of Li–O bonds. 相似文献
15.
Amanda Baker Michael Lanagan Clive Randall Elena Semouchkina George Semouchkin Khalid Z. Rajab Richard Eitel Khalid Z. Rajab Raj Mittra Sorah Rhee Peter Geggier Claus Duschl Günter Fuhr 《International Journal of Applied Ceramic Technology》2005,2(6):514-520
At the Keck Smart Materials Integration Laboratory at Penn State University, low-temperature co-fired ceramic (LTCC) material systems have been used to fabricate a number of devices for a variety of applications. This article presents an overview of the integration of the concepts and materials that we have used to achieve miniaturization and unique device function. Examples of microwave filters, metamaterial antennas, and a dielectrophoretic cell sorter will be presented, with emphasis on device modeling and design, prototype construction methods, and test results. 相似文献
16.
Katy S. Gerace John C. Mauro Clive A. Randall 《Journal of the American Ceramic Society》2021,104(5):1915-1944
Piezoelectric materials have coupled mechanical and electrical energies and have long been used in devices for actuators, sensors, energy harvesters, frequency filters, and various additional applications. Piezoelectricity requires a non-centrosymmetric crystal structure and is therefore confined to materials that possess a periodic crystalline structure. Due to the non-crystalline nature of glass, piezoelectricity is fundamentally forbidden. However, one way to exploit piezoelectric properties in a glassy matrix is by developing glass-ceramics that possess controlled growth of a crystalline phase. Growth and orientation of piezoelectric crystals in a glassy matrix is a non-trivial process that has long been explored to combine the formability of glass with the thermal and mechanical resilience of glass-ceramics. While extensive work has been done in the field of functional glass-ceramics, the results are presented in isolated articles and a comprehensive review pertaining to symmetry breaking methods to exploit anisotropic properties in glass-ceramics has been absent from the literature. Here, we present a global review of the fundamental symmetry requirements for piezoelectricity, the development of polar, piezoelectric glass-ceramic compositions (specifically those with LiNbO3 and fresnoite-based crystal phases), and various crystal growth and orientation mechanisms, including relevant kinetic and thermodynamic driving forces. Lastly, we discuss the challenges associated with implementing gradients to drive oriented crystal growth to develop non-centrosymmetry, and the need for future modeling work to produce adequate time-temperature-transformation (TTT) diagrams that take into account kinetic and thermodynamic driving forces for oriented crystal growth. Going beyond technical challenges, we conclude with an examination of current and potential applications for piezoelectric glass-ceramics that combine the formability of glass with the symmetry-dependent properties of ceramics. 相似文献
17.
Hyunjun Kim Brahim Akdim James Park Woo-Yong Jang Randall S. Hay Augustine M. Urbas Christopher Woodward 《Journal of the American Ceramic Society》2021,104(11):5659-5670
High-throughput computation, based on density functional theory (HT-DFT), is used to predict the bounds for optical transparency, from the ultraviolet to the infrared, for materials in the pyrochlore family. The HT-DFT approach adopted here uses an initial screening from Materials-Project database, with millions of calculated properties. Band gaps and phonon spectra were calculated from selected pyrochlore crystal structures taken from the Materials Project database. Short and long wavelength bounds for optical transparency were calculated for chemistries with stable, cubic structures. The calculations predict that La2Ce2O7 has one of the broadest range of transparency for the pyrochlore family. Based on these calculations, dense polycrystalline samples of La2Ce2O7 were produced by sintering and hot-isostatic pressing. Transparency was characterized by methods that did not require large samples with high optical quality, obtaining 7.15 and 7.5 µm at 95% and 90% normalized transmittance, respectively. Bandgap calculations suggest a lower bound of UV transparency cut-off of 0.3 µm. The infrared wavelength cut-off is higher than that reported for other pyrochlores, and higher than for yttria, zirconia, or other common infrared transparent ceramics. We discuss our prediction and characterization methods as well as the suitability of pyrochlores for mid- and far-infrared optical applications. 相似文献
18.
Johnny Jiung-Yee Lee Taylor Randall Paul Jen-Hwa Hu Anne Wu 《Information Systems Management》2013,30(4):340-352
Prior research has documented that IT investment increases market returns. Economic theories predict such returns to be recognized in accounting profitability; this relationship remains ambiguous in prior literature. We reexamine the relationship between IT investment and firm profitability. Our approach is unique in that we examine complementarities between distinct IT components. We document that a firm’s investments in IT components exhibit different impacts on its profitability conditional on the level of investments in complementary components. 相似文献
19.
Given a graph with edges colored Red and Blue, we study the problem of sampling and approximately counting the number of matchings with exactly k
Red edges. We solve the problem of estimating the number of perfect matchings with exactly k
Red edges for dense graphs. We study a Markov chain on the space of all matchings of a graph that favors matchings with k
Red edges. We show that it is rapidly mixing using non-traditional canonical paths that can backtrack. We show that this chain
can be used to sample matchings in the 2-dimensional toroidal lattice of any fixed size ℓ with k
Red edges, where the horizontal edges are Red and the vertical edges are Blue.
An extended abstract appeared in J.R. Correa, A. Hevia and M.A. Kiwi (eds.) Proceedings of the 7th Latin American Theoretical Informatics Symposium, LNCS 3887, pp. 190–201, Springer, 2006.
N. Bhatnagar’s and D. Randall’s research was supported in part by NSF grants CCR-0515105 and DMS-0505505.
V.V. Vazirani’s research was supported in part by NSF grants 0311541, 0220343 and CCR-0515186.
N. Bhatnagar’s and E. Vigoda’s research was supported in part by NSF grant CCR-0455666. 相似文献
20.
Abstract. We present the first optimal randomized online algorithms for the TCP acknowledgment problem [3] and the Bahncard problem
[5]. These problems are well known to be generalizations of the classical online ski-rental problem, however, they appeared
to be harder. In this paper we demonstrate that a number of online algorithms which have optimal competitive ratios of e/(e-1) , including these, are fundamentally no more complex than ski rental. Our results also suggest a clear paradigm for solving
ski-rental-like problems. 相似文献