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91.
Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82–16 μm) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest. 相似文献
92.
Longitudinal trends in networks of university-industry-government relations in South Korea: The role of programmatic incentives 总被引:1,自引:0,他引:1
This study examines the longitudinal trend of systemness in networked research relations in South Korea using a triple helix (TH) indicator of university-industry-government (UIG) relations. The data were harvested from the Science Citation Index (SCI) and its counterparts in the social sciences (SSCI) and the arts and humanities (A&HCI). The total number of Korean SCI publications has grown rapidly since 1965. However, the TH indicator shows that the network dynamics have varied considerably according to the research policies of the national government. The collaboration patterns, as measured by co-authorship relations in the SCI noticeably increased, with some variation, from the mid-1970s to the mid-1990s. However, inter-institutional collaboration in the first decade of the 21st century was negatively influenced by the new national science and technology (S&T) research policies that evaluated domestic scientists and research groups based on their international publication numbers rather than on the level of cooperation among academic, private, and public domains. The results reveal that Korea has failed to boost its national research capacity by neglecting the network effects in science, technology, and industry. 相似文献
93.
This paper investigates the problem of stabilization for fuzzy sampled-data systems with variable sampling. A novel Lyapunov–Krasovskii functional (LKF) is introduced to the fuzzy systems. The benefit of the new approach is that the LKF develops more information about actual sampling pattern of the fuzzy sampled-data systems. In addition, some symmetric matrices involved in the LKF are not required to be positive definite. Based on a recently introduced Wirtinger-based integral inequality that has been shown to be less conservative than Jensen’s inequality, much less conservative stabilization conditions are obtained. Then, the corresponding sampled-data controller can be synthesized by solving a set of linear matrix inequalities (LMIs). Finally, an illustrative example is given to show the feasibility and effectiveness of the proposed method. 相似文献
94.
This paper investigates a stability problem for linear systems with time-varying delays. By constructing suitable augmented Lyapunov–Krasovskii functionals, improved stability criteria under various conditions of time-varying delays are derived within the framework of linear matrix inequalities (LMIs). Moreover, to reduce the computational burden caused by the non-convex term including h2(t), how to deal with it is applied by estimating it to the convex term including h(t). Finally, three illustrative examples are given to show the effectiveness of the proposed criteria. 相似文献
95.
Numerous studies have been conducted about criminal justice internship programs in western countries, but few have addressed similar types of programs conducted in Eastern countries. To fill this gap in the literature, this study preliminarily analyzed the factors affecting satisfaction with the police practicum credit program in South Korea using data collected from 208 participating students and police officers. The results showed that participants were generally satisfied with the program but had different perceptions about each program component. Focusing on the crucial elements affecting overall satisfaction with the program, the study examined the following factors: the curriculum; the period and practice time; the proportion of on-site practice; teaching material; credits; and police officers’ preparedness, attitudes and information offerings. Our results suggest that the curriculum and preparedness of the officers in charge were significant factors affecting the participants’ satisfaction. Based on the findings, implications for policy recommendations are discussed. 相似文献
96.
In this paper, the problem of stability analysis for neural networks with time-varying delays is considered. By the use of a newly augmented Lyapunov functional and some novel techniques, sufficient conditions to guarantee the asymptotic stability of the concerned networks are established in terms of linear matrix inequalities (LMIs). Three numerical examples are given to show the improved stability region of the proposed works. 相似文献
97.
98.
Components of Conceptual Ecologies 总被引:1,自引:0,他引:1
Hyun Ju Park 《Research in Science Education》2007,37(2):217-237
The theory of conceptual change is criticized because it focuses only on supposed underlying logical structures and rational
process processes, and lacks attention to affective aspects as well as motivational constructs in students’ learning science.
This is a vast underestimation of the complexity and diversity of one’s change of conceptions. The notion of conceptual ecology
provides a context for understanding individuals’ conceptual change learning, as it is the environment through which all information
is interpreted. This research investigated how high school students’ statements, made in answering questions, reflect selected
components of their conceptual ecologies. Data for this study was collected from six interviews in which seven students took
part. The data also include the science teacher’s profiles of each student, the students’ personal journals, their assignments,
and their examinations and answers in class. The analysis presented will here include only those components that were represented
in the discourse of the seven high school students who were interviewed. When students were asked questions, there was evidence
of the engagement of the various components of conceptual ecologies. These components include: epistemological commitments,
metaphysical beliefs, the affective domain and emotional aspects, the nature of knowledge, the nature of learning, the nature
of conceptions, and past experience. Evidence from this study suggests that these components might function as constraints
to learning. This study contributes to the field by expanding our knowledge of the components of high school students’ conceptual
ecologies through its definition of the categories and themes associated with those components. In examining across the range
of components, the study illustrates the variety and sources of science conceptions within high school students’ conceptual
ecologies. 相似文献
99.
100.
The learning analytics dashboard (LAD) is a newly developed learning support tool for virtual classrooms that is believed to allow students to review their online learning behavior patterns intuitively through the provision of visual information. The purpose of this study was to empirically validate the effects of LAD. An experimental study was conducted with a dashboard treatment group and a control group. The researchers developed a LAD and evaluated its effectiveness on the sample of 151 college students at a private university located in Korea, who were taking the online course titled “Management Statistics” in the first semester of 2014. The following results were obtained. First, the students who received dashboard treatment presented higher final score than those who did not. Second, the dashboard usage frequency, as measured by the number of times the dashboard was opened, did not have a significant impact on learning achievement. However, a slightly positive correlation between satisfaction with LAD and learning achievement was observed. Further analysis indicated that learners who used the dashboard only a few times showed relatively high satisfaction with LAD. On the other hand, high academic achievers who opened LAD relatively frequently showed lower satisfaction with dashboard. The results guide that LAD should be revised in a way to motivate learners consistently and support learners who have different academic achievement levels. The study discusses the further research tasks in terms of LAD development as an effective and personalized feedback tool to improve learners’ academic achievement. 相似文献