A neurophysiologically‐based analysis of lightness and brightness perception

Psychophysical, achromatic luminance threshold, and scaling data have been analyzed and found to follow from nonlinear, hyperbolic responses of retinal cones. For short (0.1 s) stimulus duration, a stable state of visual adaptation could explain the threshold response, but for longer durations a change of adaptation had to be considered. This resulted in a contrast sensitivity that increased when the stimulus duration increased and became constant for higher test field luminances. Threshold and scaling data can thus be traced back to cone‐specific responses over a much larger range of stimulus intensity than has been anticipated earlier. The experimental results, including those for lightness and brightness scaling, have been compared with the CIELAB and the CIEDE2000 color formulas. The idea of combining cone responses with adaptive changes to describe luminance responses resulted in a common cone‐based response formula for describing both luminance thresholds and scaling data. Adaptive changes explain the reason why both Weber–Fechner and Stevens’ laws are valid. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 339–351, 2016     

The effects of trust and constructive controversy on student achievement and attitude in online cooperative learning environments

This study investigated the effects of trust and constructive controversy on student achievement and attitude in online cooperative learning environments. Students in one university course were randomly assigned to one of the two treatment groups after they took part in a common initial workshop on general cooperative learning skills. The “trust” and the “constructive controversy” groups received subsequent associated skills training. The overall results indicated that after each group received the treatment during online cooperative group activities, the “trust” groups had significantly higher achievement than the “constructive controversy” groups. In addition, the “trust” groups had significantly more positive attitudes toward online cooperative learning than the “constructive controversy” groups. Specifically, using “trust” building strategies was significantly more effective than using “constructive controversy” strategies for improving the ‘openness and sharing’ and ‘acceptance and support’ components of student attitudes in online cooperative learning environments.     

博弈结构、生产方式与双方道德风险组织激励

基于委托代理理论给出了双方道德风险组织激励问题的基本分析框架,建立合作与非合作博弈结构下双方道德风险组织激励问题的规划模型。以分析框架与规划模型为基础,引入线性生产与协作生产两种具体的生产方式,全面对比分析了不同博弈结构、不同生产方式下双方道德风险组织激励的均衡努力、最优契约和效用水平,揭示了不同博弈结构、不同生产方式下双方道德风险组织激励问题的特点与规律。     

A model of driver behaviour

The driver-vehicle-environment system is characterized by the driver's ability to receive information from the environment and to react upon it by activating the controls of the vehicle. Modelling this system one has to take into account that it is complex. After introducing the model the required operations for the driver's eye and hand movements are demonstrated by means of selected examples drawn from driving-simulator runs. First analyses indicate the principal applicabilities of the fuzzy driver model for further research.     

The effect of computer-assisted cooperative learning methods and group size on the EFL learners’ achievement in communication skills

This study explored the effect of cooperative learning small group size and two different instructional modes (positive interdependence vs. individual accountability) on English as a Foreign Language (EFL) undergraduate learners’ communication skills (speaking and writing) achievement in computer-based environments. The study also examined the effects of disclosing/blinding the participants’ identities while interacting around computers on their post-test. The findings of the study revealed that the computer-based environment enabled the participants to blind their identities and reduce their anxiety from face-to-face debate, and so was very helpful in developing their communication skills. The use of the individual accountability mode was quite useful compared with the positive interdependence mode as it enabled all group members to perform their roles significantly. The 5-student group also significantly outperformed other groups of 2-7 members on the post-test communication skills. In conclusion, the findings of this study bring us a step closer to understanding the technique of cooperative language learning and group size.     

Cooperative Control by System Voltage Control Equipments in Consideration of Reducing Capacity of STATCOM

In recent years, the number of renewable energy sources (RESs) such as photovoltaic generation systems and wind power generation systems connected to the grid has been increasing as a way of reducing negative effects on the environment. The outputs of these RESs vary rapidly because of the influence of the weather and the conditions of the location. Therefore, there are concerns that the point voltages in a distribution system may vary drastically and that the voltages may deviate from the appropriate voltage range as a result of the influence of the RES connected to the distribution system or to the diversification of loads. Furthermore, there are concerns about adverse effects on electric power quality, such as voltage imbalances and harmonics. In this paper, we propose a cooperative voltage control method for a distribution system using system voltage control equipment in order to reduce the capacity of the static synchronous compensator. Numerical calculations were performed in order to verify the validity of the proposed method.     

物理层安全中的最优中继选择及协同干扰策略

本文提出了一种以协同干扰为基础,结合了最优中继选择和功率分配的物理层安全方案.该方案针对分布式天线的场景,从中间节点中选择一个最佳的节点作为中继,剩余的其他节点作为协同干扰节点.中继节点使用放大转发策略.本文同时提出了协同干扰节点的波束成形算法.另外,我们还推导出了中继节点和协同干扰节点之间的功率分配的闭式解.最后,本文还给出了相关的仿真结果,证实了新提出的方案比传统方案能获得更高的安全容量.     

跨小区多跳中继协作通信的无线通信能效优化 *

针对蜂窝网中某一基站处于体眠状态时引起各用户的通信中断问题,提出利用中继协作通信实现跨小区多跳通信的迭代中继选择算法.该算法是在有多个中继节点可为目的节点提供协作中继时,将源节点到目的节点的数据传输分为3个连续时隙,选择满足目的节点信噪比最大化的中继,以协作效率为依据删除协作效率最小的中继节点,从而逐次优化中继选择结果.仿真结果表明,该算法在跨小区多跳的通信过程中,能选择出协作效率最高的中继节点,减少协作中继的数量,可以减少中继对能源不必要的消耗,改善小区内中继协作效率,在多跳的过程中节省源节点的发射功率,从而达到能效优化的目的.     

一种基于Ad Hoc网络的协作MAC方案

在 IEEE 802.11b MAC层协议的研究基础上,提出了一种基于无线Ad Hoc网络的最佳中继选择策略,该策略综合考虑瞬时信道信息和节点剩余能量,能够有效防止信道条件好的节点的过度使用,并能保证系统高吞吐量。文中以饱和吞吐量和网络生存时间为性能指标,对新算法和以往协作MAC算法进行仿真和比较,结果表明新算法在网络吞吐量下降不明显的情况下,能大大增加网络生存时间。