Time-domain training sequences design for MIMO OFDM channel estimation     

Zhen Lu  Jian-hua Ge 《浙江大学学报(A卷英文版)》2008,9(4):464-469

This paper describes a Least Squares （LS） channel estimation scheme for MIMO OFDM systems based on time-domain training sequence. We first compute the minimum mean square error （MSE） of the LS channel estimation, and then derive the optimal criteria of the training sequence with respect to the minimum MSE. It is shown that optimal time-domain training sequence should satisfy two criteria. First, the autocorrelation of the sequence transmitted from the same antenna is an impulse function in a region longer than the channel maximum delay. Second, the cross-correlation between sequences transmitted from different antennas is zero in this region. Simulation results show that the estimator using optimal time-domain training sequences has better performance than that using optimal frequency training sequence at low signal-to-noise ratio （SNR）. To reduce the training overhead, a suboptimal training sequence is also proposed. Comparing with optimal training sequence, it has low computation complexity and high transmission efficiency at the expense of little performance degradation.  相似文献   

Beyond Archaeology and Genealogy     

Dany Nobus 《Metascience》2005,14(3):419-421

  相似文献   

Remembering Gould     

John S. Wilkins 《Metascience》2007,16(1):169-173

  相似文献   

Editorial     

Jérôme Rossier 《International Journal for Educational and Vocational Guidance》2016,16(1):5-8

  相似文献   

A new patch antenna with metamaterial cover   总被引：6，自引：0，他引：6  

胡骏阎春生  林青春 《浙江大学学报(A卷英文版)》2006,7(1):89-94

INTRODUCTION Investigation of metamaterials is currently one of the most active frontiers in engineering and physics. Metamaterials are also called backward-wave mate- rials, double-negative materials, or left-handed mate- rials. Left-handed materials were proposed by Vese- lago (1968). The applications of metamaterials are widely spread in many fields (Pendry, 2000; Grbic and Eleftheriades, 2003; Foteinopoulou et al., 2003), such as imaging apparatus, planar light wave circuits, optica…  相似文献   

Students’ approaches to groupwork in a blended course,associations with perceptions of the online environment and academic achievement – when is learning engaged?     

Robert A. Ellis 《Education and Information Technologies》2016,21(5):1095-1112

University teachers provided first year Arts students with hundreds of cinematic images online to analyse as a key part of their predominantly face-to-face undergraduate course. This qualitative study investigates the extent to which the groups engaged in learning involving their analysis of the images and how this was related to their perception of the ICT-mediated environment. Interviews and questionnaires completed by students revealed that the extent of engaged learning was related to the quality of the approach to groupwork reported by the students, the quality of their approach to the analysis of the images and their perceptions of key aspects of the online environment which provided the images. The findings have implications for the design and approach to teaching best suited for students involved in groupwork and the use of ICT resources provided to promote engaged experiences of learning.  相似文献   

Reading Instruction for English Learners in the Middle Grades: a Meta-Analysis     

Colby Hall  Garrett J. Roberts  Eunsoo Cho  Lisa V. McCulley  Megan Carroll  Sharon Vaughn 《Educational Psychology Review》2017,29(4):763-794

This meta-analysis synthesizes the last two decades of experimental and quasi-experimental research on reading instruction across academic contexts (e.g., social studies, science, mathematics, English language arts) for English learners (ELs) in grades 4 through 8, to determine (a) the overall effectiveness of reading instruction for upper elementary and middle school students who are ELs and (b) how the magnitude of the effect varies based on student, instructional, and study characteristics. The analysis included a total of 11 studies with 46 individual effect sizes and yielded a mean effect size of g?=?0.35 across all (i.e., standardized and unstandardized) reading measures, g?=?0.01 across standardized reading measures, and g?=?0.43 across unstandardized reading measures. For all reading, unstandardized reading, all vocabulary, and unstandardized vocabulary measures, results suggest that higher quality studies tended to have smaller effects, and these effects were even more evident for unstandardized measures (i.e., one unit increase in study quality was associated with decreased effects: g?=?0.21, g?=?0.30, g?=?0.24, g?=?0.30, respectively). For all comprehension measures, effects were larger for instruction that included both vocabulary and comprehension (g?=?0.39) than for instruction that focused on vocabulary alone (g?=?0.08). Results suggest the benefit of developing and refining high-impact approaches to reading instruction for ELs that can be delivered across content areas and grades.  相似文献   

Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine     

严兆大  周重光  苏石川  刘震涛  王希珍 《浙江大学学报(A卷英文版)》2003,4(2):170-174

In order to predict and improve the performance of natural gas/diesel dual fuel engine (DFE), a combustion rate model based on forward neural network was built to study the combustion process of the DFE. The effect of the operating parameters on combustion rate was also studied by means of this model. The study showed that the predicted results were good agreement with the experimental data. It was proved that the developed combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine. Project supported by National Lab. for Automotive Engine and Safety, Tsinghua University, China  相似文献   

3. Winfried D’Avis. Der informierte Mensch. Sein Weltbild-Sein Gehirn-Sein Computer     

Claus J. Tully  Dirk Baier 《Zeitschrift für Erziehungswissenschaft》2003,6(2):303-304

  相似文献   

The Hidden Curriculum of Domestication     

Juan S. Muñoz  Rosario Ordoñez Jasis  Patricia A. Young  Peter McLaren 《The Urban Review》2004,36(3):169-187

Four ethnically diverse faculty members in the field of education discuss the professional impact and personal affects of introducing critical themes of race, class, gender, and culture within their research and course offerings. Given that the professional outlook for university faculty of color in general, is grim, a willingness to imbue their research and courses with a critical interrogation of prevailing education topics and theories would seem to invite greater personal risk and professional jeopardy. The following dialogue introduces both the mechanisms by which critical faculty in general, and faculty of color in particular, can be conditioned to subordinate their critical impulses and the strategies they use to resist academic cultures of domestication.  相似文献