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排序方式: 共有2544条查询结果,搜索用时 15 毫秒
161.
Cristian Bucilă Johannes Gehrke Daniel Kifer Walker White 《Data mining and knowledge discovery》2003,7(3):241-272
Recently, constraint-based mining of itemsets for questions like find all frequent itemsets whose total price is at least $50 has attracted much attention. Two classes of constraints, monotone and antimonotone, have been very useful in this area. There exist algorithms that efficiently take advantage of either one of these two classes, but no previous algorithms can efficiently handle both types of constraints simultaneously. In this paper, we present DualMiner, the first algorithm that efficiently prunes its search space using both monotone and antimonotone constraints. We complement a theoretical analysis and proof of correctness of DualMiner with an experimental study that shows the efficacy of DualMiner compared to previous work. 相似文献
162.
Heverhagen JT Ishaque N Zielke A Bohrer T Sitter H Berthold LD Klose KJ 《Magma (New York, N.Y.)》2001,12(1):4-9
Purpose: The purpose of this study was to evaluate MRI as a diagnostic tool in patients with suspected acute sigmoid diverticulitis.
Furthermore, we sought to develop an optimal imaging protocol in these patients.Patients and methods: Eleven patients with suspected acute diverticulitis were included in the study. All patients were imaged in a 1.0 T clinical
scanner using a body-array coil. Imaging sequences were single-shot TSE, HASTE-, STIR- and TrueFisp-sequence. All were obtained
in the frontal plane. The diagnosis was verified by a single experienced investigator, using ultrasound, and overall clinicopathological
outcome.Results: MRI enabled visualization of signs of an acute diverticulitis in all patients. However, the diagnosis of acute diverticulitis
was obtained in 10 patients only. The mean imaging time was 17.5 ± 5.5 min. STIR- and TrueFisp-sequences alone displayed all
findings, e.g pericolonic exsudation, edema and segmental narrowing, whereas SSTSE and HASTE-sequences showed no additional
information. Therefore, it appeared that the imaging protocol could be restricted to STIR- and TrueFisp-sequences.Conclusion: MRI is feasible as a fast, accurate and investigator-independent diagnostic tool in patients with suspected acute diverticulitis.
To prove its value in comparison to computed tomography or ultrasound, further studies are needed. 相似文献
163.
Fair webs are energy-minimizing curve networks. Obtained via an extension of cubic splines or splines in tension to networks of curves, they are efficiently computable and possess a variety of interesting applications. We present properties of fair webs and their discrete counterparts, i.e., fair polygon networks. Applications of fair curve and polygon networks include fair surface design and approximation under constraints such as obstacle avoidance or guaranteed error bounds, aesthetic remeshing, parameterization and texture mapping, and surface restoration in geometric models. 相似文献
164.
Mario Drobics Johannes Himmelbauer 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2007,11(5):421-438
In this paper we will present a novel approach to data-driven fuzzy modeling which aims to create highly accurate but also
easily comprehensible models. This is achieved by a three-stage approach which separates the definition of the underlying
fuzzy sets, the learning of the initial fuzzy model, and finally a local or global optimization of the resulting model. The
benefit of this approach is that it allows to use a language comprising of comprehensible fuzzy predicates and to incorporate
expert knowledge by defining problem specific fuzzy predicates. Furthermore, we achieve highly accurate results by applying
a regularized optimization technique. 相似文献
165.
H. Rosner M.D. Johannes M. Schmitt W. Schnelle Y.-X. Huang 《Science and Technology of Advanced Materials》2007,8(5):352-356
Based on electronic structure calculations within the density functional theory, we report a systematic approach for the modelling of low-dimensional CuII materials. Combining concepts of crystal chemistry with ab initio-based magnetic models, we present a systematic study of recently discovered compounds. Our calculation results are in good agreement with thermodynamic and magnetic measurements, suggesting the presented approach as a well-directed route to explore the magnetic phase diagram of low-dimensional CuII systems. 相似文献
166.
167.
168.
Johannes Fürnkranz Christian Holzbaur Robert Temel 《Applied Artificial Intelligence》2013,27(4):243-281
Melvil is an ontology-based knowledge retrieval platform that provides a three-dimensional visualization of search results. The user can tailor the presentation of the search results to his or her preferences by changing the settings of various parameters on the screen. In this paper, we report on a prototype implementation of a user profiling device that learns to predict appropriate settings for these parameters for the current search results based on previous experiences. In a preliminary study, we evaluated several off-the-shelf machine learning algorithms on parts of the problem. The final implementation required the flexibility of handling both regression and classification problems, being able to deal with set-valued input and output attributes, as well as incorporating Melvil 's ontologies for the respective application domain. Thus, we selected a nearest-neighbor approach for the prototype implementation. An evaluation on off-line data collected from several users showed a satisfactory performance. 相似文献
169.
Johannes Griss Yasset Perez-Riverol Henning Hermjakob Juan Antonio Vizcaíno 《Proteomics. Clinical applications》2015,9(3-4):437-443
In this article we discuss the requirements to use data mining of published proteomics datasets to assist proteomics-based biomarker discovery, the use of external data integration to solve the issue of inadequate small sample sizes and finally, we try to estimate the probability that new biomarkers will be identified through data mining alone. 相似文献
170.
Henning Buddenbaum Oksana Stern Barbara Paschmionka Erik Hass Thomas Gattung Johannes Stoffels 《International journal of remote sensing》2013,34(18):4590-4605
Drought stress is expected to become a recurrent problem for central European forests due to regional climate change. In order to study the effects on one of the most common tree species in Germany, the European beech (Fagus sylvatica), young potted beech trees were exposed to drought stress in a controlled experiment and their reaction was observed using visible/near-infrared (VNIR) and shortwave infrared (SWIR) field imaging spectroscopy cameras mounted on a platform. Equivalent water thickness (EWT) and leaf chlorophyll content (LCC) were measured and partial least squares (PLS) regression models were trained using these reference measurements and reflectance spectra of the trees. The models were applied to create maps of these properties with a spatial resolution in the millimetre range. These maps can be used to study the spatial distribution of EWT and LCC for single leaves or even for intra-leaf variability. Both properties can be estimated using only the VNIR sensor, but EWT estimation improves considerably by also incorporating SWIR data. LCC estimations with SWIR data alone do not work satisfactorily. 相似文献