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31.
Extracting Hidden Context 总被引:4,自引:0,他引:4
Concept drift due to hidden changes in context complicates learning in many domains including financial prediction, medical diagnosis, and communication network performance. Existing machine learning approaches to this problem use an incremental learning, on-line paradigm. Batch, off-line learners tend to be ineffective in domains with hidden changes in context as they assume that the training set is homogeneous. An off-line, meta-learning approach for the identification of hidden context is presented. The new approach uses an existing batch learner and the process of contextual clustering to identify stable hidden contexts and the associated context specific, locally stable concepts. The approach is broadly applicable to the extraction of context reflected in time and spatial attributes. Several algorithms for the approach are presented and evaluated. A successful application of the approach to a complex flight simulator control task is also presented. 相似文献
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Bassel Shaer Jean‐Pierre Kenné Claude Kaddissi Honorine Angue Mintsa 《国际强度与非线性控制杂志
》2017,27(18):4968-4991
》2017,27(18):4968-4991
Electrohydraulic actuators are an attractive choice for active suspension, because these systems provide a high power‐to‐weight ratio. However, their dynamics are highly nonlinear. In addition, the use of one simple controller for both position and force is complicated, because there is a compromise between them in the case of active suspension. Most existing controllers do not efficiently fulfill the requirements, because only one state variable is considered. In this paper, we address these problems by developing a new hybrid controller for both position and force and implementing it in a real‐time test bench. Our goal is to control the vertical position of the passenger seat while tracking the force transmitted to passengers and keeping it within tolerable and comfortable limits. Therefore, the proposed controller is a combination of two controllers. Its flexible structure redirects the control signal to control the proper controlled state variable. The real‐time results of the newly designed hybrid controller are compared with those obtained using a classical proportional integral derivative controller, because this is the most widely used controller in the industry. As expected, the proposed controller demonstrates better performance in real‐time operation. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Synthetic sapphire and yttria-stabilized zirconia single-crystals were irradiated by increasing doses of γ-radiation to study the changes of their optical properties. The optical transparency of -Al2O3 was nearly constant up to the γ-radiation dose of 150 kGy for the spectral range of 400–1000 nm, while yellowish-brown coloration of (Zr0.89Y0.11)O1.94 appeared for irradiation above 1 kGy. However, after a short-term heating in the temperature of 210oC stable discoloration of zirconia can be achieved. 相似文献
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Claude Cookman 《History of Photography》2013,37(2):199-207
Abstract When news of the assassination of Mohandas Gandhi circulated through New Delhi on 30 January 1948, Margaret Bourke-White, one of Life magazine's premier photographers, and Henri Cartier-Bresson, then a comparatively unknown French photojournalist, raced to Birla House, where the event occurred. Both understood the journalistic imperative of photographing Gandhi's body. Because of their different philosophical and technical approaches to photography, they responded to the challenge in different ways and produced very different results. This study compares their ideas, approaches, and results. It also offers a case study of one of Cartier-Bresson' s most important news reportages.1 相似文献
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In this paper, we illustrate specific power savings obtained from exploiting a reconfigurable mobile terminal under the 3GPP LTE standard. Building on traditional link adaptation towards maximum throughput and extended towards minimal power consumption, we add two flexible baseband components: the turbo decoder and the multiple input multiple output (MIMO) detector. Optimizing their configuration leads to larger power savings when compared to non-flexible systems only performing link adaptation. The gain observed strongly depends on the scenario. For low-activity set-ups with a few minutes of voice per day, the idle power dominates and the active data rate is relatively low. This makes analog front-end and time-domain processing dominant given their constant power consumption while MIMO detection and turbo decoding that scale with data rate play a smaller role. Still, because of its ability to improve the system spectral efficiency and hence reduce its duty cycle, an advanced MIMO detector can save 10% in power consumption, on the condition that the network requires to use MIMO. Otherwise single input single output is more power-efficient in downlink. In high-throughput scenarios, larger gains are obtained. The flexible MIMO detector can save up to 35% of average power consumption. The turbo decoding also brings some gain, saving up to 12% of power when the full bandwidth is allocated to a single user. 相似文献
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