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21.
In this study, we designed and developed an app called Ubiquitous-Physics (U-Physics) for mobile devices like tablet PC or smart phones to help students learn the principles behind a simple pendulum in Physics. The unique characteristic of U-Physics is the use of sensors on mobile devices to collect acceleration and velocity data during pendulum swings. The data collected are transformed to facilitate students’ understanding of the pendulum time period. U-Physics helped students understand the effects of pendulum mass, length, and angle in relation to its time period. In addition, U-Physics was equipped with an annotation function such as textual annotation to help students interpret and understand the concepts and phenomena of the simple pendulum. U-Physics also generated graphs automatically to demonstrate the time period during which the pendulum was swinging. Results showed a significant positive correlation between interpreting graphs and applying formula. This finding indicated that the ability to interpret graphs has an important role in scientific learning. Therefore, we strongly recommend that physics teachers use graphs to enrich students’ information content and understanding and negative correlation between pair coherence and interpreting graphs. It may be that most of the participants (vocational high school students) have limited skill or confidence in physics problem solving; so, they often seek help from teachers or their high-achieving peers. In addition, the findings also indicated that U-Physics can enhance students’ achievement during a 3-week time period. We hope that this app can be globally used to learn physics in the future.  相似文献   
22.
A method of using orthogonal shifted Legendre polynomials for identifying the parameters of a process whose behaviour can be modelled by a linear differential equation with time-varying coefficients in the form of finite-order polynomials is presented. It is based on the repeated integration of the differential equation and the representations of 0ts(τ) dτ = Ps(t) and ts(t) = Rs(t), where P and R are constant matrices and s(t) is a shifted Legendre vector whose elements are shifted Legendre polynomials. The differential input-output equation is converted into a set of overdetermined linear algebraic equations for a least squares solution. The results of simulation studies are included to illustrate the applicability of the method.  相似文献   
23.
A new combined time and frequency domain method for the model reduction of discrete systems in z-transfer function is presented. First, the z-transfer functions are transformed into the w-domain by the bilinear transformation, z = (1+w)/(1?w). Then, four model reduction methods—Routh approximation, Hurwitz polynomial approxima- tion, stability equation, and retaining dominant poles—are used respectively to reduce the order of the denominator polynomials in the w-domain. Least squares estimate is then used to find the optimal coefficients in the numerator polynomials of the reduced models so that the unit step response errors are reduced to a minimum. The advantages of the proposed method are that both frequency domain and time domain characteristics of the original systems can be preserved in the reduced models, and the reduced models are always stable provided the original models are stable.  相似文献   
24.
Recent advances in mobile and wireless communication technologies have enabled various new learning approaches which situate students in environments that combine real‐world and digital‐world learning resources; moreover, students are allowed to share knowledge or experiences with others during the learning process. Although such an approach seems to be promising and innovative, researchers have indicated several problems when applying it to practical applications, in particular, the lack of proper strategies or tools to assist the students to learn collaboratively in such a learning scenario with abundant content. Students might feel interested when using the mobile devices to learn; however, without proper assistance or guidance, their learning achievements are usually disappointing. To cope with this problem, this study proposes a concept map‐oriented Mindtool for collaborative ubiquitous learning. Experimental results from a natural science course in an elementary school show that this approach not only enhances learning motivation but also improves the learning achievements of the students.  相似文献   
25.
Previous studies have demonstrated that making annotations can be a meaningful and useful learning method that promote metacognition and enhance learning achievement. A web‐based annotation system, Virtual Pen (VPEN), which provides for the creation and review of annotations and homework solutions, has been developed to foster learning process among students. In order to explore the effects of reviewing annotations and homework solutions on learning achievement, a quasi‐experiment was conducted with VPEN in a math class over a period of 4 months. It was found that reviewing own text annotations has a significant influence on learning achievement; while on the contrary, reviewing peers' text annotations has no significant influence on learning achievement. Our results show that students gain more from reviewing their own annotations than from reviewing the annotations made by peers, a contrast which reveals that annotations hold additional meaning for their creators. Further investigation revealed that only the quantity of text annotations among all other variables can significantly predict students' learning achievement. This finding may suggest that text annotations play more important roles to learning achievement than other variables, like homework. The reason is because text annotations are created by learners actively on voluntary base whereas homework is usually assigned by the teachers. Based on our findings, we suggest that teachers may consider incorporating learning activities that can foster metacognitive development into the learning process, like making annotations, solving homework and reviewing them, whereas peer learning should be encouraged only for reviewing the homework solutions of their peers with good learning achievement.  相似文献   
26.
最近几年,像美国许多城市一样,莫德斯托(Modesto)也一直遭到媒体裁员和开支削减的冲击.记者的责任比从前更大了,他们越来越多地依靠微博、Facebook、博客、谷歌等采集新闻和报道.在这种数字转变之前,记者对美国贫穷的工人阶级的报道不仅偏少而且往往是脸谱化的或遭到扭曲的.如今,社交媒体使更多公民参与到地方新闻的制作和传播中来.这种新平台能帮助被边缘化的声音更好地在媒体上展现吗?  相似文献   
27.
Huang CT  Weng CH  Jen CP 《Biomicrofluidics》2011,5(4):44101-4410111
Particle focusing in microfluidic devices is a necessary step in medical applications, such as detection, sorting, counting, and flow cytometry. This study proposes a microdevice that combines insulator-based and metal-electrode dielectrophoresis for the three-dimensional focusing of biological cells. Four insulating structures, which form an X pattern, are employed to confine the electric field in a conducting solution, thereby creating localized field minima in the microchannel. These electrodes, 56-μm-wide at the top and bottom surfaces, are connected to one electric pole of the power source. The electrodes connected to the opposite pole, which are at the sides of the microchannel, have one of three patterns: planar, dual-planar, or three-dimensional. Therefore, low-electric-field regions at the center of the microchannel are generated to restrain the viable HeLa cells with negative dielectrophoretic response. The array of insulating structures aforementioned is used to enhance the performance of confinement. According to numerical simulations, three-dimensional electrodes exhibit the best focusing performance, followed by dual-planar and planar electrodes. Experimental results reveal that increasing the strength of the applied electric field or decreasing the inlet flow rate significantly enhances focusing performance. The smallest width of focusing is 17 μm for an applied voltage and an inlet flow rate of 35 V and 0.5 μl/min, respectively. The effect of the inlet flow rate on focusing is insignificant for an applied voltage of 35 V. The proposed design retains the advantages of insulator-based dielectrophoresis with a relatively low required voltage. Additionally, complicated flow controls are unnecessary for the three-dimensional focusing of cells.  相似文献   
28.
Educational technology research and development - Gender and prior knowledge may affect students' performance and motivation when simulations and games are used for learning. Accommodations...  相似文献   
29.
Educational technology research and development - Review strategies after learning new knowledge are essential for students to consolidate the key points, understand the subject content, analyze...  相似文献   
30.
The purpose of this study was to describe the physical activity levels of urban inner city preschoolers while attending Head Start, the federally funded preschool program for children from low-income families. Participants were 158 African American children. Their physical activity during Head Start days was measured using programmed RT-3 accelerometers. Results revealed that the children spent the most time in sedentary and light physical activity, while their participation in moderate-to-vigorous physical activities was low. Given the sedentary class format and limited physical space for the Head Start programs observed, we suggest adding a structured physical activity component to Head Start schools to fight the overweight and obesity crisis.  相似文献   
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