Thermal mixing of two miscible fluids in a T-shaped microchannel     

Xu B  Wong TN  Nguyen NT  Che Z  Chai JC 《Biomicrofluidics》2010,4(4):44102

In this paper, thermal mixing characteristics of two miscible fluids in a T-shaped microchannel are investigated theoretically, experimentally, and numerically. Thermal mixing processes in a T-shaped microchannel are divided into two zones, consisting of a T-junction and a mixing channel. An analytical two-dimensional model was first built to describe the heat transfer processes in the mixing channel. In the experiments, de-ionized water was employed as the working fluid. Laser induced fluorescence method was used to measure the fluid temperature field in the microchannel. Different combinations of flow rate ratios were studied to investigate the thermal mixing characteristics in the microchannel. At the T-junction, thermal diffusion is found to be dominant in this area due to the striation in the temperature contours. In the mixing channel, heat transfer processes are found to be controlled by thermal diffusion and convection. Measured temperature profiles at the T-junction and mixing channel are compared with analytical model and numerical simulation, respectively.  相似文献   

Micro-optofluidic Lenses: A review   总被引：2，自引：0，他引：2  

Nam-Trung Nguyen 《Biomicrofluidics》2010,4(3)

This review presents a systematic perspective on the development of micro-optofluidic lenses. The progress on the development of micro-optofluidic lenses are illustrated by example from recent literature. The advantage of micro-optofluidic lenses over solid lens systems is their tunability without the use of large actuators such as servo motors. Depending on the relative orientation of light path and the substrate surface, micro-optofluidic lenses can be categorized as in-plane or out-of-plane lenses. However, this review will focus on the tunability of the lenses and categorizes them according to the concept of tunability. Micro-optofluidic lenses can be either tuned by the liquid in use or by the shape of the lens. Micro-optofluidic lenses with tunable shape are categorized according to the actuation schemes. Typical parameters of micro-optofluidic lenses reported recently are compared and discussed. Finally, perspectives are given for future works in this field.  相似文献   

Relations between goals,self‐efficacy,critical thinking and deep processing strategies: a path analysis     

Huy Phuong Phan 《教育心理学》2009,29(7):777-799

Research exploring students’ academic learning has recently amalgamated different motivational theories within one conceptual framework. The inclusion of achievement goals, self‐efficacy, deep processing and critical thinking has been cited in a number of studies. This article discusses two empirical studies that examined these four theoretical orientations from both cross‐sectional (N = 279 participants) and longitudinal (N = 264 participants) perspectives. In particular, achievement goals are hypothesised to exert direct and indirect effects on academic performance via self‐efficacy, study processing strategies and critical thinking. Path analysis was used to test and analyse the hypothesised conceptual models. Results from SPSS 16 and LISREL 8.72 provided good support for the hypothesised structural relationships. Students’ academic performance outcomes, for example, are determined directly by deep processing and work‐avoidance goals. Results from Study 2 indicate mastery goals and self‐efficacy, mastery goals and critical thinking and deep processing and critical thinking operate in a reciprocal manner. In general, the evidence established from both studies contributes theoretically and methodologically.  相似文献   

Impacts of higher education quality accreditation: a case study in Vietnam     

Huong Thi Pham 《Quality in Higher Education》2018,24(2):168-185

Quality accreditation in higher education exists in many countries, including Vietnam. As of May 2018, 80 higher education institutions in Vietnam have officially been evaluated and recognised using the national quality standards. This study examined the impact of institutional accreditation on the evaluated university. The qualitative research evaluates the impact of external quality assurance from the perspective of managers of the university. The self-assessment phase helped the university assemble evidence of activities carried out at the university and the status of being recognised was believed to increase its prestige. The process, on the other hand, was also believed to be burdensome, time and cost consuming, which led to no significant changes at the institution. Lack of institutional autonomy and competence of the review team were barriers to any attempts to improve quality of higher education in Vietnam.  相似文献   

Towards an understanding of dynamics among teachers,teacher leaders,and administrators in a teacher-led school reform     

Tuan D. Nguyen  Seth Hunter 《Journal of Educational Change》2018,19(4):539-565

A substantial amount of professional development and implementation has moved towards teachers and teacher leaders in recent years. Previous works have examined how teachers, teacher leaders, or administrators perceive teacher leadership in school reforms, but few have advanced all three perspectives simultaneously. Drawing upon over 200 interviews, we examine how leadership is distributed and the tensions and dynamics arising among these three groups in a teacher-led school reform. Two main themes emerged from our analysis: minimizing conflicts with teachers was important to teacher leaders, and the distribution of leadership between administrators and teacher leaders changed the status and normative roles of teacher leaders.  相似文献   

Informational sources,self-efficacy and achievement: a temporally displaced approach     

Huy Phuong Phan 《教育心理学》2012,32(6):699-726

Personal self-efficacy is an important theoretical orientation that helps to explain students’ learning and academic achievements. One area of research inquiry has involved the four major sources of information and their predictive effects on self-efficacy. As an extension for examination, the purpose of our investigation was to explore the interrelations between antecedents (e.g. enactive performance accomplishment), self-efficacy beliefs and academic achievement of elementary school students. Our research conceptualisation, unlike previous cross-sectional studies, entails a time displacement between sources of information (Time 1) and self-efficacy (Time 2 and Time 3) and between self-efficacy and academic achievement in science learning (Time 4). Three hundred and thirty-two (152 girls and 180 boys) third and fourth grade students from three government schools participated in this study. Likert-scale inventories were used to measure informational sources and self-efficacy beliefs. Structural equation modelling yielded evidence that supports, in part, our conceptual model. Only enactive performance accomplishment and vicarious experience exerted positive temporally displaced effects on self-efficacy. Self-efficacy at both Time 2 and Time 3 also contributed to the prediction of academic achievement.  相似文献   

Inductive Selectivity in Children's Cross-Classified Concepts     

SP Nguyen 《Child development》2012,83(5):1748-1761

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Comparison of 3D reconstructive technologies used for morphometric research and the translation of knowledge using a decision matrix     

Charys M. Martin  Victoria A. Roach  Ngan Nguyen  Charles L. Rice  Timothy D. Wilson 《Anatomical sciences education》2013,6(6):393-403

The use of three‐dimensional (3D) models for education, pre‐operative assessment, presurgical planning, and measurement have become more prevalent. With the increase in prevalence of 3D models there has also been an increase in 3D reconstructive software programs that are used to create these models. These software programs differ in reconstruction concepts, operating system requirements, user features, cost, and no one program has emerged as the standard. The purpose of this study was to conduct a systematic comparison of three widely available 3D reconstructive software programs, Amira^®, OsiriX, and Mimics^®, with respect to the software's ability to be used in two broad themes: morphometric research and education to translate morphological knowledge. Cost, system requirements, and inherent features of each program were compared. A novel concept selection tool, a decision matrix, was used to objectify comparisons of usability of the interface, quality of the output, and efficiency of the tools. Findings indicate that Mimics was the best‐suited program for construction of 3D anatomical models and morphometric analysis, but for creating a learning tool the results were less clear. OsiriX was very user‐friendly; however, it had limited capabilities. Conversely, although Amira had endless potential and could create complex dynamic videos, it had a challenging interface. These results provide a resource for morphometric researchers and educators to assist the selection of appropriate reconstruction programs when starting a new 3D modeling project. Anat Sci Educ 6: 393–403. © 2013 American Association of Anatomists.  相似文献   

Between the Structural and the Personal: Situated Sense-Makings of “Race” This research was supported by a grant from the MOSAIC Multicultural Center at San Jose State University.     

Rona Tamiko Halualani  Deanna L. Fassett  Jennifer Huynh Thi Anh Morrison  Patrick Shaou-Whea Dodge 《传播与批判/文化研究》2013,10(1):70-93

Using a critical intercultural communication perspective and cultural studies interviewing method, this study traces individuals’ subjective sense-makings of diversity through the trope of “race.” Such sense-makings represent the key (and taken-for-granted) locus of the structural and personal where social actors live out the constructions of diversity and race in deeply felt ways. Our study reveals how individuals articulate and understand race via raceless diversity encodings (whereby race is seemingly stripped of its power inequalities, and all racial/ethnic groups are made equal) and racial pivoting (whereby participants both discursively pull away from and move toward race to suit their individual experiences).  相似文献   

Micromixer based on viscoelastic flow instability at low Reynolds number   总被引：1，自引：0，他引：1  

Y. C. Lam  H. Y. Gan  N. T. Nguyen    H. Lie 《Biomicrofluidics》2009,3(1)

We exploited the viscoelasticity of biocompatible dilute polymeric solutions, namely, dilute poly(ethylene oxide) solutions, to significantly enhance mixing in microfluidic devices at a very small Reynolds number, i.e., Re≈0.023, but large Peclet and elasticity numbers. With an abrupt contraction microgeometry (8:1 contraction ratio), two different dilute poly(ethylene oxide) solutions were successfully mixed with a short flow length at a relatively fast mixing time of <10 μs. Microparticle image velocimetry was employed in our investigations to characterize the flow fields. The increase in velocity fluctuation with an increase in flow rate and Deborah number indicates the increase in viscoelastic flow instability. Mixing efficiency was characterized by fluorescent concentration measurements. Our results showed that enhanced mixing can be achieved through viscoelastic flow instability under situations where molecular-diffusion and inertia effects are negligible. This approach bypasses the laminar flow limitation, usually associated with a low Reynolds number, which is not conducive to mixing.  相似文献