Text Categorization based on Clustering Feature Selection

AbstractIn this paper, we discuss a text categorization method based on k-means clustering feature selection. K-means is classical algorithm for data clustering in text mining, but it is seldom used for feature selection. For text data, the words that can express correct semantic in a class are usually good features. We use k-means method to capture several cluster centroids for each class, and then choose the high frequency words in centroids as the text features for categorization. The words extracted by k-means not only can represent each class clustering well, but also own high quality for semantic expression. On three normal text databases, classifiers based on our feature selection method exhibit better performances than original classifiers for text categorization

Uncertainty quantification tools for multiphase gas-solid flow simulations using MFIX

Computational fluid dynamics (CFD) has been widely studied and used in the scientific community and in the industry. Various models were proposed to solve problems in different areas. However, all models deviate from reality. Uncertainty quantification (UQ) process evaluates the overall uncertainties associated with the prediction of quantities of interest. In particular it studies the propagation of input uncertainties to the outputs of the models so that confidence intervals can be provided for the simulation results. In the present work, a non-intrusive quadrature-based uncertainty quantification (QBUQ) approach is proposed. The probability distribution function (PDF) of the system response can be then reconstructed using extended quadrature method of moments (EQMOM) and extended conditional quadrature method of moments (ECQMOM). The method is first illustrated considering two examples: a developing flow in a channel with uncertain viscosity, and an oblique shock problem with uncertain upstream Mach number. The error in the prediction of the moment response is studied as a function of the number of samples, and the accuracy of the moments required to reconstruct the PDF of the system response is discussed. The approach proposed in this work is then demonstrated by considering a bubbling fluidized bed as example application. The mean particle size is assumed to be the uncertain input parameter. The system is simulated with a standard two-fluid model with kinetic theory closures for the particulate phase implemented into MFIX. The effect of uncertainty on the disperse-phase volume fraction, on the phase velocities and on the pressure drop inside the fluidized bed are examined, and the reconstructed PDFs are provided for the three quantities studied. Then the approach is applied to a bubbling fluidized bed with two uncertain parameters. Contour plots of the mean and standard deviation of solid volume fraction, solid phase velocities and gas pressure are provided. The PDFs of the response are reconstructed using EQMOM with appropriate kernel density functions. The simulation results are compared to experimental data provided by the 2013 NETL small-scale challenge problem. Lastly, the proposed procedure is demonstrated by considering a riser of a circulating fluidized bed as an example application. The mean particle size is considered to be the uncertain input parameters. Contour plots of the mean and standard deviation of solid volume fraction, solid phase velocities, and granular temperature are provided. Mean values and confidence intervals of the quantities of interest are compared to the experiment results. The univariate and bivariate PDF reconstructions of the system response are performed using EQMOM and ECQMOM

Modelling progressive failure in multi-phase materials using a phase field method

In this paper, a new phase field method is proposed for modelling of progressive failure in multi-phase materials. Material properties of the interface between inclusion and matrix are regularized by an auxiliary interface phase field. In addition, crack initiation and propagation are simulated by using another crack phase field. Different failure mechanisms such as interface debonding, matrix cracking and the interaction between these two failure mechanisms are modelled in a unified framework. For general application of the framework, an image processing method is employed to identify the individual phases for a given multi-phase material. The proposed method is implemented into the commercial software ABAQUS through a user subroutine UEL (user defined element). The derived method is validated through an example of a single fiber reinforced composite system. Moreover, a procedure for choosing parameters of the proposed phase field model is discussed. Further, the validated method is applied to fracture analysis of a multi-phase concrete structure and complex failure mechanisms within and across the phases are captured

Toward a More PERMA(nent) Conceptualization of Worker Well-Being? A Cross-Cultural Study of the Workplace PERMA Profiler

We examined the factor structure of the recently developed worker well-being measure the Workplace PERMA Profiler and relationships between PERMA dimensions (i.e., positive emotions, engagement, positive relationships, meaning, accomplishment) and job performance (viz., task performance, organizational citizenship behaviors benefiting individuals and the organization at large). The measure exhibited metric (i.e., weak) invariance across samples of participants from the U.S. (N = 284) and China (N = 420). Additionally, for participants who responded to both the Workplace PERMA Profiler and the performance measures, there was a general pattern of positive PERMA–performance relationships across both samples (NU.S. = 147; NChina = 202). Overall, the Workplace PERMA Profiler may have problematic psychometric properties and item wordings and thus would benefit from further refinement

Phosphorylation of TGB1 by protein kinase CK2 promotes barley stripe mosaic virus movement in monocots and dicots.

The barley stripe mosaic virus (BSMV) triple gene block 1 (TGB1) protein is required for virus cell-to-cell movement. However, little information is available about how these activities are regulated by post-translational modifications. In this study, we showed that the BSMV Xinjiang strain TGB1 (XJTGB1) is phosphorylated in vivo and in vitro by protein kinase CK2 from barley and Nicotiana benthamiana. Liquid chromatography tandem mass spectrometry analysis and in vitro phosphorylation assays demonstrated that Thr-401 is the major phosphorylation site of the XJTGB1 protein, and suggested that a Thr-395 kinase docking site supports Thr-401 phosphorylation. Substitution of Thr-395 with alanine (T395A) only moderately impaired virus cell-to-cell movement and systemic infection. In contrast, the Thr-401 alanine (T401A) virus mutant was unable to systemically infect N. benthamiana but had only minor effects in monocot hosts. Substitution of Thr-395 or Thr-401 with aspartic acid interfered with monocot and dicot cell-to-cell movement and the plants failed to develop systemic infections. However, virus derivatives with single glutamic acid substitutions at Thr-395 and Thr-401 developed nearly normal systemic infections in the monocot hosts but were unable to infect N. benthamiana systemically, and none of the double mutants was able to infect dicot and monocot hosts. The mutant XJTGB1T395A/T401A weakened in vitro interactions between XJTGB1 and XJTGB3 proteins but had little effect on XJTGB1 RNA-binding ability. Taken together, our results support a critical role of CK2 phosphorylation in the movement of BSMV in monocots and dicots, and provide new insights into the roles of phosphorylation in TGB protein functions