Societal lifetime cost of hydrogen fuel cell vehicles

This paper employs societal lifetime cost for evaluating hydrogen fuel cell vehicles (FCVs) from a societal welfare perspective as compared to conventional gasoline vehicles. We employ a learning-curve model for fuel-cell system cost estimates over time. The delivered hydrogen fuel cost is estimated using the UC Davis SSCHISM hydrogen supply pathway model, and most vehicle costs are estimated using the Advanced Vehicle Cost and Energy-Use Model (AVCEM). To estimate external costs, we use AVCEM and the Lifecycle Emissions Model (LEM). We examine hydrogen transition costs for a range of market penetration rates, externality evaluations, technology assumptions, and oil prices. Our results show that although the cost difference between FCVs and gasoline vehicles is initially very large, FCVs eventually become lifetime cost competitive with gasoline vehicles as their production volume increases, even without accounting for externalities. High valuation of externalities and high oil price could reduce the buy-down cost (the cumulative investment needed to bring hydrogen FCVs to lifetime cost parity with gasoline vehicles) by $10 billion relative to our reference case.     

高职计算机应用基础课程教学改革的探讨

该文对如何利用考证促学和模块化案例教学相结合的方式,来促进高职计算机应用基础教学,培养学生的计算机综合应用能力进行探讨。     

Learner outcomes and satisfaction: A comparison of live video-streamed instruction,satellite broadcast instruction,and face-to-face instruction

This study examined the final grade and satisfaction level differences among students taking specific courses using three different methods: face-to-face in class, via satellite broadcasting at remote sites, and via live video-streaming at home or at work. In each case, the same course was taught by the same instructor in all three delivery methods, and an attempt was made to survey students taking the course via the three different delivery methods. MANOVA results indicated no grade or satisfaction level differences among the three populations. Self-reported computer literacy skills revealed a slight fit between the chosen delivery mode and the reported computer literacy skills. These results provide additional evidence to support both the “no significant difference” phenomenon and the use of distance education as a viable, convenient and flexible alternative delivery mode capable of extending learning opportunities to non-traditional students.     

Real time implementation of CTRNN and BPTT algorithm to learn on-line biped robot balance: Experiments on the standing posture

This paper describes experimental results regarding the real time implementation of continuous time recurrent neural networks (CTRNN) and the dynamic back-propagation through time (BPTT) algorithm for the on-line learning control laws. Experiments are carried out to control the balance of a biped robot prototype in its standing posture. The neural controller is trained to compensate for external perturbations by controlling the torso’s joint motions. Algorithms are embedded in the real time electronic unit of the robot. On-line learning implementations are presented in detail. The results on learning behavior and control performance demonstrate the strength and the efficiency of the proposed approach.     

A note on “Single machine scheduling with time-dependent deterioration and exponential learning effect”

result in a recent paper Huang, Wang, Wang, Gao, and Wang (2010) (Computers & Industrial Engineering 58 (2010) 58–63) is incorrect because job processing times are variable due to both deteriorating jobs and learning effects, which is not taken into account by the authors. In this note, we show by a counter-example that the published result is incorrect.     

Hypermedia and learning: Contrasting interfaces to hypermedia systems

This study explores selected theoretical and design issues associated with the use of hypermedia learning environments to promote the recall, synthesis, integration and retention of information. The study contrasts two different hypermedia systems that contain resources on a complex historical domain. The experimental condition incorporates design features related to complexity, context-dependency and interconnectedness in order to highlight different aspects of its instructional content. The experimental condition was hypothesized to foster greater achievement on tests for synthesis, integration and retention of knowledge and to be more favorably rated by users. The control condition incorporates simple linear design features including several features that are antithetical to those of the experimental condition. The control condition presents the same instructional content in a more rigid and decontextualized manner and was hypothesized to foster greater mastery of factual recall but less synthesis, integration and retention of knowledge. Results however demonstrated that participants in the control condition were able to recall more facts, make more connections between themes in the test for synthesis and retain more facts than participants in the experimental condition. However, differences in overall performance for both hypermedia systems were not statistically significant: neither system had a different effect on learning.     

妊娠期和哺乳期连续微波辐射对小鼠学习记忆功能的影响与甲状腺激素作用研究

本研究主要探讨妊娠期间和哺乳期间连续微波辐射，对胎鼠和乳鼠成年后学习记忆功能的影响，以及甲状腺激素T3、T4在其中的作用。实验采用SPF级昆明小鼠48只，分为妊娠期组与哺乳期组，并分别设立对照组，采用30mW／cm^2的微波，每天一次性辐射20min，连续辐射，其中对照组只做假辐射处理。妊娠期组自妊娠第1天起辐射至孕鼠分娩，共辐射21天；哺乳期组自出生第1天起连续辐射21天。在辐射第15天时分别取孕鼠和乳鼠血清，采用放免法测血清中游离T3、T4（F13、FT4）含量，待胎鼠及乳鼠成年后（2月龄）采用Morris水迷宫检测其学习记忆功能。研究发现妊娠期辐射组血清FT4明显低于对照组（p〈0．05），而FV3没有显著变化；在定位导航实验中，其寻找平台的潜伏期明显高于对照组（p〈0．05），空间搜索实验中在目的象限的停留时间（17．70±7．07s）明显低于对照组（27．14±5．36s）（p〈0．05），跨越虚拟平台的次数（0．83±0．41）也明显低于对照组（1．67±0．52）（p〈0．01）哺乳期辐射组血清FT4没有显著变化，而FT3显著降低（p〈0．05）；在Morris水迷宫实验中，其各项检测指标与对照组相比，没有显著差异。以上结果表明，哺乳期间连续微波辐射能导致乳鼠血清FT3降低，但对乳鼠成年后学习记忆功能无明显影响；妊娠期间连续微波辐射能导致孕鼠血清FT4降低，胎鼠成年后学习记忆功能下降，提示FT4下降可能是微波辐射致胎鼠成年后学习记忆功能下降的因素之一。     

Learning-based algorithms in scheduling

The aim of the paper is to present a conception of intelligent learning-based algorithms for scheduling. A general knowledge based model of a vast class of discrete deterministic processes is given. The model is a basis for the method of the synthesis of intelligent, learning-based algorithms, that is described in the paper. The designing simulation experiments that use learning is also described. To illustrate the presented ideas, the scheduling algorithm for a special NP-hard problem is given. The significant feature of the problem is that the retooling time depends not only on a pair of jobs to be processed directly one after the other, but also on the subset of jobs already performed. The proof of the NP-hardness of the problem is also given in the paper.     

Context-free and context-sensitive dynamics in recurrent neural networks

Continuous-valued recurrent neural networks can learn mechanisms for processing context-free languages. The dynamics of such networks is usually based on damped oscillation around fixed points in state space and requires that the dynamical components are arranged in certain ways. It is shown that qualitatively similar dynamics with similar constraints hold for aⁿbⁿcⁿ , a context-sensitive language. The additional difficulty with aⁿbⁿcⁿ , compared with the context-free language aⁿbⁿ , consists of 'counting up' and 'counting down' letters simultaneously. The network solution is to oscillate in two principal dimensions, one for counting up and one for counting down. This study focuses on the dynamics employed by the sequential cascaded network, in contrast to the simple recurrent network, and the use of backpropagation through time. Found solutions generalize well beyond training data, however, learning is not reliable. The contribution of this study lies in demonstrating how the dynamics in recurrent neural networks that process context-free languages can also be employed in processing some context-sensitive languages (traditionally thought of as requiring additional computation resources). This continuity of mechanism between language classes contributes to our understanding of neural networks in modelling language learning and processing.