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41.
Tomoko Watanabe Traphagan Yueh-hui Vanessa Chiang Hyeseung Maria Chang Benjaporn Wattanawaha Haekyung Lee Michael Charles Mayrath Jeongwon Woo Hyo-Jin Yoon Min Jung Jee Paul E. Resta 《Computers & Education》2010
Using a framework of cognitive, social, and teaching presence, the nature of learning experiences in a three-dimensional virtual world environment (Second Life) and a text-chat learning environment without visuals (TeachNet) were investigated. A mixed method of code frequencies, coherence graphs, interviews, and a survey was used. The results revealed that the TeachNet debates included more cognitive presence codes that indicate higher levels of cognitive processing than in SL debates. The teams were significantly different from each other in the collaboration style for developing arguments and in the ways to use utterances associated with cognitive, social, and teaching presences, and the groups’ collaboration style became more established with more experience with the tasks. The three critical factors–tool, tasks and group cohesion–that affect cognitive, teaching, and social presence are discussed. 相似文献
42.
The Lucas–Kanade tracker (LKT) is a commonly used method to track target objects over 2D images. The key principle behind
the object tracking of an LKT is to warp the object appearance so as to minimize the difference between the warped object’s
appearance and a pre-stored template. Accordingly, the 2D pose of the tracked object in terms of translation, rotation, and
scaling can be recovered from the warping. To extend the LKT for 3D pose estimation, a model-based 3D LKT assumes a 3D geometric
model for the target object in the 3D space and tries to infer the 3D object motion by minimizing the difference between the
projected 2D image of the 3D object and the pre-stored 2D image template. In this paper, we propose an extended model-based
3D LKT for estimating 3D head poses by tracking human heads on video sequences. In contrast to the original model-based 3D
LKT, which uses a template with each pixel represented by a single intensity value, the proposed model-based 3D LKT exploits
an adaptive template with each template pixel modeled by a continuously updated Gaussian distribution during head tracking.
This probabilistic template modeling improves the tracker’s ability to handle temporal fluctuation of pixels caused by continuous
environmental changes such as varying illumination and dynamic backgrounds. Due to the new probabilistic template modeling,
we reformulate the head pose estimation as a maximum likelihood estimation problem, rather than the original difference minimization
procedure. Based on the new formulation, an algorithm to estimate the best head pose is derived. The experimental results
show that the proposed extended model-based 3D LKT achieves higher accuracy and reliability than the conventional one does.
Particularly, the proposed LKT is very effective in handling varying illumination, which cannot be well handled in the original
LKT. 相似文献
43.
Wen-Bin Lin Huann-Keng Chiang Kuang-Rong Shih Chien-An Chen 《Artificial Life and Robotics》2010,15(4):473-477
This article proposes the PC-based LabVIEW as the software to develop the algorithm of the robust complex extended Kalman
filter (RCEKF) to detect the parameters of the voltage signal in power systems. The hardware used is a sample-and-hold card
and a data acquisition (DAQ) card to extract the data from an outside system to the PC, and the program will compute the amplitude,
frequency, and phase of the voltage signal with RCEKF. To validate the performance of RCEKF, the voltage signal from a function
generator was applied to check the feasibility of the algorithm. This application was also used in the Taiwan Power Company
(TPC) secondary substation in Sijhou, Taiwan. 相似文献
44.
In this article, a sliding mode control (SMC) design based on a Gaussian radial basis function neural network (GRBFNN) is
proposed for the synchronous reluctance motor (SynRM) system in electrical motorcycle applications. The conventional SMC assumes
that the upper lumped boundaries of parameter variations and external disturbances are known, and the sign function is used.
This causes high-frequency chattering and the high-gain phenomenon. In order to avoid these drawbacks, the proposed method
utilizes the Lyapunov stability method and the steep descent rule to guarantee the convergence asymptotically, and reduce
the magnitude of the chattering or avoid it completely. Finally, numerical simulations are shown to illustrate the good performance
of our controller design. 相似文献
45.
Cheng-Feng Tai Tzu-Chiang Chiang Ting-Wei Hou 《Expert systems with applications》2011,38(3):2099-2109
Resolving the broadcast storm problem is an important issue in mobile ad hoc networks (MANETs). In this paper, we propose an approach for constructing a virtual subnet whose nodes are logically related. The virtual subnet can be spread upon clusters of a MANET. An intelligent agent with a routing filtering table is proposed to assist the best known clustering algorithms, the original Least ID algorithm and the original Highest Connection Cluster (HCC) algorithm, to improve group communication efficiency. Our simulation covers the network factors of hop count, deprave rate, and delay time. The simulation results show that when the proposed intelligent agent is used with the HCC algorithm, the delay time was reduced by 81.84% as compared with flooding, and by 49.25% as compared with the Ad Hoc On-Demand Distance Vector (AODV) routing algorithm. The delay time for the Least ID algorithm assisted by the proposed agents reduced by 81.84% compared to that of flooding and by 50% compared to that of AODV. 相似文献
46.
Krishna Tushar Kumar Amit Peh Li-Shiuan Postman Jacob Chiang Patrick Erez Mattan 《Micro, IEEE》2009,29(4):48-61
Networks on chip must deliver high bandwidth at low latencies while keeping within a tight power envelope. Using express virtual channels for flow control improves energy-delay throughput by letting packets bypass intermediate routers, but EVCs have key limitations. Nochi (NoC with hybrid interconnect) overcomes these limitations by transporting data payloads and control information on separate planes, optimized for bandwidth and latency respectively. 相似文献
47.
The conventional game theory is concerned with how rational individuals make decisions when they are faced with known payoffs. In the real world, sometimes the payoffs are not known and have to be estimated, and sometimes the payoffs are only approximately known. This paper develops a solution method for the two-person zero-sum game where the payoffs are imprecise and are represented by interval data. Since the payoffs are imprecise, the value of the game should be imprecise as well. A pair of two-level mathematical programs is formulated to obtain the upper bound and lower bound of the value of the game. Based on the duality theorem and by applying a variable substitution technique, the pair of two-level mathematical programs is transformed to a pair of ordinary one-level linear programs. Solving the pair of linear programs produces the interval of the value of the game. It is shown that the two players in the game have the same upper bound and lower bound for the value of the imprecise game. An example illustrates the whole idea and sheds some light on imprecise game. 相似文献
48.
A knowledge-based decision support system to analyze the debris-flow problems at Chen-Yu-Lan River, Taiwan 总被引:5,自引:0,他引:5
Decision-making for the debris-flow management involves multiple decision-makers often with concerning geomorphological and hydraulic conditions. Spatial decision support systems (SDSS) can be developed to improve our understanding of the relations among the natural and socio-economic variables to the occurrence/non-occurrence samples of debris-flow. Accordingly, the goal of this study is to development a debris-flow decision support system to manage and monitor the debris-flows in Nan-Tou County, Taiwan. The present study, more specifically, combines a spatial information system with an advanced Data Mining technique to investigate the debris-flow problem. In the first stage, our spatial information system integrates remote sensing, DEM, and aerial photos as three different resources to generate our spatial database. Each of the geomorphological and hydraulic attributes are obtained automatically through our spatial database. Then, a Data Mining classifier (hybrid model of decision tree (D.T.) + support vector machine (S.V.M.)) will be used to analyze and resolve the classification of occurrence of debris-flow. The contribution of this study has found that watershed area and NDVI (Normalized Difference Vegetation Index) are the crucial factors governing debris-flow by means of decision tree analysis. Further, the performance of prediction accuracy on testing samples through support vector machine is 73% which could be helpful for us to have better understanding of debris-flow problem. 相似文献
49.
Y.-M. Chiu C.-T. Hung F.-N. Hwang M.-H. Chiang J.-S. Wu S.-H. Chen 《Computer Physics Communications》2011,(1):167-169
The effect on the selection of different plasma chemistries for simulating a typical dielectric barrier discharge (DBD) driven by quasi-pulsed power source (20 kHz) is investigated. The numerical simulation was performed by using the one-dimensional self-consistent fluid modeling solver. Our simulation result indicates that the computed temporal current density can be significantly improved by using a complex version of plasma chemistry module rather than the simple one and demonstrates an excellent agreement with the experimental data. The result suggests the metastable, excited and ionic helium related reaction channels, which are important in simulating a DBD, should be taken into account. Furthermore, it also reveals that the power absorption of ions is considerably higher than that of the electron. 相似文献
50.
Ming-Chao Chiang Author Vitae Chun-Wei Tsai Author Vitae Chu-Sing Yang Author Vitae 《Information Sciences》2011,181(4):716-3410
This paper presents an efficient algorithm, called pattern reduction (PR), for reducing the computation time of k-means and k-means-based clustering algorithms. The proposed algorithm works by compressing and removing at each iteration patterns that are unlikely to change their membership thereafter. Not only is the proposed algorithm simple and easy to implement, but it can also be applied to many other iterative clustering algorithms such as kernel-based and population-based clustering algorithms. Our experiments—from 2 to 1000 dimensions and 150 to 10,000,000 patterns—indicate that with a small loss of quality, the proposed algorithm can significantly reduce the computation time of all state-of-the-art clustering algorithms evaluated in this paper, especially for large and high-dimensional data sets. 相似文献