Channel adaptive rate control for energy optimization     

Blanch Carolina  Pollin Sofie  Lafruit Gauthier  Eberle Wolfgang 《浙江大学学报(A卷英文版)》2006,7(1):82-88

Low energy consumption is one of the main challenges for wireless video transmission on battery limited devices. The energy invested at the lower layers of the protocol stack involved in data communication, such as link and physical layer, represent an important part of the total energy consumption. This communication energy highly depends on the channel conditions and on the transmission data rate. Traditionally, video coding is unaware of varying channel conditions. In this paper, we propose a cross-layer approach in which the rate control mechanism of the video codec becomes channel-aware and steers the instantaneous output rate according to the channel conditions to reduce the communication energy. Our results show that energy savings of up to 30% can be obtained with a reduction of barely 0.1 dB on the average video quality. The impact of feedback delays is shown to be small. In addition, this adaptive mechanism has low complexity, which makes it suitable for real-time applications.  相似文献   

Counselor education in the Counseling Institute of Sophia University,Tokyo, Japan     

Kobayashi  Michael J. 《International journal for the advancement of counseling》1981,4(1):45-49

International Journal for the Advancement of Counselling -  相似文献   

Between-limb differences in running technique induces asymmetric negative joint work during running     

Satoru Hashizume  Hiroaki Hobara  Yoshiyuki Kobayashi 《European Journal of Sport Science》2019,19(6):757-764

Negative work, which is mainly generated by eccentric muscle contraction, has an important influence on the associated muscle damage. Generally, mechanical parameters are determined for one side of a lower extremity on the assumption of negligible between-limb differences. However, between-limb differences in the negative work of lower extremity joints during running remain unclear. This study examines between-limb differences in negative work and associated mechanical parameters during the contact phase of running. Twenty-five young adult males voluntarily participated in this study. Each participant was asked to run on a straight runway at a speed of 3.0?m?s^?1. Negative work, amplitude, duration of negative power, moment, and angular velocity were computed for both sides of the lower extremities. Significant differences were found in negative work between limbs for the hip (18.9?±?11.7%), knee (13.6?±?10.4%), and ankle (11.8?±?8.5%) joints. For the hip joint, asymmetric negative work was attributable to the between-limb difference in the amplitude of negative power owing to a corresponding difference in the moment. The between-limb differences concerning the duration and amplitude of negative power could explain the asymmetric negative work in the knee joint. The asymmetric negative work of the ankle joint was attributable to the between-limb difference in the amplitude and duration of the negative power and the moment. These results indicate that asymmetric negative work was generated in each lower extremity joint; however, the major mechanical parameters corresponding to the negative work are not the same across the joints.  相似文献   

RIM: A Random Item Mixture Model to Detect Differential Item Functioning     

Sofie Frederickx  Francis Tuerlinckx  Paul De Boeck  David Magis 《Journal of Educational Measurement》2010,47(4):432-457

In this paper we present a new methodology for detecting differential item functioning (DIF). We introduce a DIF model, called the random item mixture (RIM), that is based on a Rasch model with random item difficulties (besides the common random person abilities). In addition, a mixture model is assumed for the item difficulties such that the items may belong to one of two classes: a DIF or a non-DIF class. The crucial difference between the DIF class and the non-DIF class is that the item difficulties in the DIF class may differ according to the observed person groups while they are equal across the person groups for the items from the non-DIF class. Statistical inference for the RIM is carried out in a Bayesian framework. The performance of the RIM is evaluated using a simulation study in which it is compared with traditional procedures, like the likelihood ratio test, the Mantel-Haenszel procedure and the standardized p -DIF procedure. In this comparison, the RIM performs better than the other methods. Finally, the usefulness of the model is also demonstrated on a real life data set.  相似文献   

The validity and reliability of relative body fat estimates and the construction of new prediction equations for young Japanese adult males.     

Shinichi Demura  Shunsuke Yamaji  Fumio Goshi  Hidetsugu Kobayashi  Susumu Sato  Yoshinori Nagasawa 《Journal of sports sciences》2002,20(2):153-164

The aims of this study were to assess the reliability and validity of three methods of bioelectrical impedance analysis (based on induction between the hand and foot, between one foot and the other foot and between one hand and the other hand) and the skinfold method, and to construct prediction equations for total body density by examining cross-validity in young Japanese adult males. The participants were 50 Japanese males aged 18-27 years (height 1.72 +/- 0.06 m, body mass 64.9 +/- 9.0 kg; mean +/- s), each of whom was measured twice using each of the four methods. Relative body fat based on underwater weighing was used as the criterion for validity. To construct prediction equations for body density, we used multiple regression analysis, whereby all possible combinations were examined. The reliability of all three bioelectrical impedance methods was high (R = 0.999). Three new prediction equations were constructed for the hand-foot method, foot-foot method and skinfold method. The cross-validity of the equations was guaranteed. The relative body fat calculated using the new equations did not differ from that based on the underwater weighing method.  相似文献   

News audience fragmentation in the Japanese Twittersphere     

Tetsuro Kobayashi  Takahisa Suzuki  Hitoshi Yamamoto 《亚洲交流杂志》2019,29(3):274-290

ABSTRACT

Although computational approaches to ideology-based audience fragmentation are promising, they are not without limitations. First, most existing studies have focused on the US, and the cross-national validity of their results has rarely been tested. Second, previous studies that rely solely on behavioral data from social media tend to make strong analytical assumptions such as that Twitter users prefer to follow media and politicians whose ideological positions are similar to their own, and that the ideologies of political elites can be extrapolated to infer the ideologies of ordinary users. We aim to address these limitations. First, we focus on Japan to test the generalizability of US findings in an Asian context. Second, we do not rely solely on behavioral measurement but combine survey and social media data to infer the ideologies of Twitter users. Results indicate that our classifier built based on these self-reported ideologies produces more valid estimates than naïve extrapolation from views of the elites. Based on these improved estimates of Twitter users’ ideologies, we demonstrate that the ideological distributions of those who follow major Japanese media accounts on Twitter largely overlap, suggesting an absence of ideology-based audience fragmentation.  相似文献   

Endorsing achievement goals exacerbates the big-fish-little-pond effect on academic self-concept     

Sofie Wouters  Hilde Colpin  Jan Van Damme  Karine Verschueren 《教育心理学》2015,35(2):252-270

The big-fish-little-pond effect (BFLPE) model predicts students’ academic self-concept to be negatively predicted by the achievement level of their reference group, controlling for individual achievement. Despite an abundance of empirical evidence supporting the BFLPE, there have been relatively few studies searching for possible moderators. Integrating the BFLPE model with Achievement Goal Theory, the present study aims to determine whether the negative effect of class-average achievement on academic self-concept is moderated by individual and class-average achievement goals. Our sample comprised of 2987 students (50% boys) from Grade 6 in 112 elementary schools in the Flemish region of Belgium (174 classes). Applying multilevel modelling, we found a stronger BFLPE when students’ individual achievement goals were higher, regardless of the specific nature of these goals. The BFLPE was not moderated by class-average levels of achievement goals. Overall, our findings demonstrate that the BFLPE is moderated by individual goal-related factors.  相似文献   

The effect of peer group performance on the self-concept of reading in a foreign language     

Rianne Janssen  Sofie Wouters  Tine Huygh  Katrijn Denies  Karine Verschueren 《教育心理学》2015,35(2):158-175

According to the big-fish-little-pond (BFLP) model, the self-concept is not only influenced in a positive way by one’s own achievement, but also in a negative way by one’s relative achievement in comparison with one’s immediate peers. This study investigates whether the BFLP effect also holds for second language acquisition. A random sample of 9167 Dutch-speaking students from Grade 8 took a reading comprehension test in French followed by a short background questionnaire in which they were asked for their self-concept of reading French. Multilevel regressions of the latter on individual and group achievement confirmed the BFLP effect but did not confirm an interaction of the effect with gender, individual achievement or class size. Moreover, in line with the local dominance hypothesis, it was shown that the negative effect of the average performance of peers is stronger for classmates than for schoolmates.  相似文献   

Preschool Children’s Foreign Language Vocabulary Learning by Embodying Words Through Physical Activity and Gesturing     

Konstantina Toumpaniari  Sofie Loyens  Myrto-Foteini Mavilidi  Fred Paas 《Educational Psychology Review》2015,27(3):445-456

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A robot is watching me!: Five-year-old children care about their reputation after interaction with a social robot     

Yuko Okumura  Takashi Hattori  Sanae Fujita  Tessei Kobayashi 《Child development》2023,94(4):865-873

Since robots are becoming involved in children's lives, it is urgent to determine how children perceive robots. The present study assessed whether Japanese 5-year-olds care about their reputation when interacting with a social robot. Children were given stickers and asked to divide them between themselves and an absent recipient. Results revealed that children (N = 112, 55 boys, 57 girls) strategically shared more stickers when being watched by a social interactive robot than by an attentional but non-interactive robot or a still robot. Additionally, children (N = 36, 18 boys, 18 girls) attributed higher psychological properties to social robots. This study is the first to show that 5-year-olds care about their reputations from social robots.  相似文献