Computational fluid dynamics(CFD) simulation of effect of baffles on separation in mixer settler

The main ideas in the development of the solvent extraction mixer settler focused on achieving clean phase separation,minimizing the loss of the reagents and decreasing the surface area of the settlers.The role of baffles in a mechanically agitated vessel is to ensure even distribution,reduce settler turbulence,promote the stability of power drawn by the impeller and to prevent swirling and vortexing of liquid,thus,greatly improving the mixing of liquid.The insertion of the appropriate number of baffles clearly improves the extent of liquid mixing.However,excessive baffling would interrupt liquid mixing and lengthen the mixing time.Computational fluid dynamics(CFD) provides a tool for determining detailed information on fluid flow(hydrodynamics) which is necessary for modeling subprocesses in mixer settler.A total of 54 final CFD runs were carried out representing different combinations of variables like number of baffles,density and impeller speed.CFD data shows that amount of separation increases with increasing baffles number and decreasing impeller speed.

STATISTICAL FEATURE OF PITCH FREQUENCY DISTRIBUTIONS FOR OBUST SPEAKER IDENTIFICATION

This letter proposes an effective and robust speech feature extraction method based on statistical analysis of Pitch Frequency Distributions (PFD) for speaker identification. Compared with the conventional cepstrum, PFD is relatively insensitive to Additive White Gaussian Noise (AWGN), but it does not show good performance for speaker identification, even if under clean environments. To compensate this shortcoming, PFD and conventional cepstrum are combined to make the ultimate decision, instead of simply taking one kind of features into account.Experimental results indicate that the hybrid approach can give outstanding improvement for text-independent speaker identification under noisy environments corrupted by AWGN.

Highlights in Museum Education

The aim of this paper is to research museum audience and its expectations, experiences, and influence on museum＇s practices at the Sinebrychoff Art Museum in Finland. The common idea is that museum pedagogy as a word creates easily an image of dusty, silent, and serious moment when the audience is forced to follow a lecture or a guided tour The author＇s research questions are： （I） Museum as an institution--what are the limits and possibilities to create highlights for audience work？ （2） How to look and talk about art for different audiences--also for non-visitors？ And （3） How can museum combine the knowledge of results and new technology to create more interesting approach for its audiences？ Participants of the author＇s research are teachers, students, senior citizens, and colleagues from other museums. Besides the literature the author uses mixed methods by combining visitor questionnaires （made during last ten years） and qualitative research made by narrative methods. Interviews have been made by H4 recorder. The qualitative analysis is going to be made by Atlas.ti. The results will finally be analyzed in 2014. Until now, it has become clear that museum experience mostly starts from the web pages. What can we offer, how to give value to our museum audience？

Hybrid RANS/LES Simulations of Two and Three Dimensional Supersonic Cavity Flows

Supersonic unsteady flows of two and three dimensional cavities, which have the same basic measures, length, depth and aft wall angle, are investigated numerically by using hybrid RANS/LES （Reynolds-Averaged Navier-Stokes/Large-Eddy Simulation） method. In particular, the mass exchange and oscillation characteristics of the cavities are analyzed and compared. It is shown that the two and three dimensional cavities have almost the same residence time except that the three dimensional one has a little larger mass decay at beginning, which may attribute to the influence of the streamwise vortices. The two dimensional cavity has three dominant frequencies while the three dimensional one has only one oscillation dominant frequency, that is, the three dimensional effects simplify the oscillation modes in the cavity. The distributions of oscillation energy are approximately universal in the transverse and spanwise directions. However, the oscillation energy in the streamwise direction shows a hybrid monotone/periodic distribution, which may be caused by the streamwise-propagating pressure waves.

Using Graded-Conversations to Enhance Language Learning and Student Collaboration

Language teaching entails the use of varied methods to maximize learning. Most language educators, particularly those teaching foreign languages tend to use lesson review sheets, dialogue practice, drills on grammar, audio tapes or text recordings. Educators also make use of media to enhance learning while a few language instructors use graded-conversations. Thus, this paper explores ways in which graded-conversations impact language learning. This paper shows how using graded-conversations in a Swahili language classroom enhanced language learning and encouraged students to collaborate in and outside the classroom. More specifically, the findings indicate that while graded-conversations motivated students to communicate with each other beyond classroom and use social media to help each other study, assignments shape the type and quality of students＇ collaboration. Implications for teaching are presented.

纳西语的升调——从共时分布类型及演变看字调升调的历史来源

对词汇、合音变调和语法变调穷尽式的整理和分析表明,纳西语的升调分字调和非字调两大类(5小类)。字调升调(1小类)多出现在古人声汉语借词中,而固有词中则极少分布,共时分布暗示字调升调是后来发展的。非字调类(4小类)由合音和语法变调产生。共时上部分合音升调出现词汇化为字调升调的趋势,据此可推测固有词中的字调升调可能来源于历史上相似的过程,而非直接来自汉语借词。合音调词汇化受语音和句法环境的制约。此外,象声词和儿语词也进一步丰富了字调升调。字调升调的出现看来是多种因素共同作用的结果。深入描写和分析纳西语的升调有助于重新认识其声调系统以及演变,同时也为探索藏缅语声调类型学描写方法和理论提供了新证据。