水泥回转窑一维数学模型研究进展及趋势

全面系统地综述了国内外水泥回转窑一维数学模型,重点介绍了传热模型、料床运动模型、煤粉燃烧模型和熟料矿物形成模型。应用MATLAB编程、求解,展示并分析了不同模型及关键参数对模拟结果的影响。在此基础上,展望了回转窑一维数学模型的发展趋势。     

食品包装材质对消费者绿色购买意愿影响的眼动研究

目的 探讨食品包装材质对消费者注意加工流程和绿色购买意愿影响的内在机制。方法 采用包装材质2(环保/普通)×食品类型2(实用品/享乐品)双因素实验设计,在货架购物场景下采用Tobii Glasses 2眼镜式眼动仪,采集被试者浏览货架不同食品时的眼动数据(平均注视时间、注视次数、热点图),并结合行为数据综合分析。结果 在平均注视时间上,包装材质与食品类型的交互作用显著,注视次数交互作用不显著;环保材质包装的食品获得更多关注,被试者偏好于选择环保包装的享乐食品。结论 包装材质与食品类型共同影响消费者的视觉感知效果与加工过程,环保包装对青年消费者的绿色购买意愿有正向促进作用。     

An approach to discovering multi-temporal patterns and its application to financial databases

Managerial decision-making processes often involve data of the time nature and need to understand complex temporal associations among events. Extending classical association rule mining approaches in consideration of time in order to obtain temporal information/knowledge is deemed important for decision support, which is nowadays one of the key issues in business intelligence. This paper presents the notion of multi-temporal patterns with four different temporal predicates, namely before, during, equal and overlap, and discusses a number of related properties, based on which a mining algorithm is designed. This enables us to effectively discover multi-temporal patterns in large-scale temporal databases by reducing the database scan in the generation of candidate patterns. The proposed approach is then applied to stock markets, aimed at exploring possible associative movements between the stock markets of Chinese mainland and Hong Kong so as to provide helpful knowledge for investment decisions.     

Comparison of two tools for the measurement of interfragmentary movement in femoral neck fractures stabilised by cannulated screws

Achieving stability at the site of femoral neck fracture is an important factor for callus formation in the post-operative period. However, measuring interfragmentary movement in vivo is not currently possible as telemetric screws have not been manufactured for surgical use. Understanding how the implantation of the screws can affect the stability of the fracture allows the surgeon to tailor the procedure to the patient and produce the best possible outcome. Two techniques have been developed that measure interfragmentary movement between fractured surfaces. The first was a FEA model of the proximal femur with screws represented by nodal links. Movement was quantified by the amount of relative motion occurring between paired nodes either side of the fracture. The second was a mechanical compression test of a composite femur that allowed the motion analysis of paired markers on the external surface of the femur. Movement was digitised with markers selected and displacements calculated by transforming the global coordinate system to a local system relative to the fracture plane.     

数据库系统原理课程中性能调优实验的设计与实践

论述了浙江大学计算机科学与技术学院采用数据库性能调优作为课程实验内容,分析讨论实验的过程、要求和内容安排等。性能调优是数据库系统应用开发的一项重要工作,具有实践性强、综合知识要求高等特点,非常适合于在探究型教学中作为实验内容。在本科生的数据库课程教学中进行了实践,取得了较好的效果。     

招贴设计形态的空间延伸性探析

本文以招贴设计的空间形态作为突破点进行理论与实践探讨,分析如何从平面空间向立体空间、静止空间向运动空间的延伸来完成招贴设计形态的多维性创新,并提出了具体可行的创作方法,通过创意与表现形式的结合来完成招贴设计形态在空间上的延伸设计。     

Optimization of multi-task turning operations under minimal tool waste consideration

Most of the literatures on machining economics problems tend to focus on single cutting operations. However, in reality most parts that need to be machined require more than one operation. In addition, machining technology has been developed to the point that a single computer numerical control (CNC) machine is capable of performing multiple operations, even simultaneously, employing multiple spindles and cutting tools. When several operations are performed on a CNC turning machine, various tools are required for the cutting operations. Determining the life of these cutting tools under different machining conditions is an arduous task for the operators. They usually replace the tools based on their experience or according to the specific cutting tool handbook. Frequent tool replacements may result in wasted tools and tool utilization, while infrequent tool replacements may result in poorly machined parts. In this study we propose a mathematical model in which several different turning operations (turning, drilling, and parting) with proper constraints are performed. The issue of tool replacement is taken into account in the proposed cutting model. In addition, an evolutionary strategy (ES)-based optimization approach is developed to optimize the cutting conditions of the multiple turning-related operations while taking into account the minimizing unit cost criteria under the economical tool replacement strategy.     

Improving traversability of quadruped walking robots using body movement in 3D rough terrains

This paper presents a study on improving the traversability of a quadruped walking robot in 3D rough terrains. The key idea is to exploit body movement of the robot. The position and orientation of the robot are systematically adjusted and the possibility of finding a valid foothold for the next swing is maximized, which makes the robot have more chances to overcome the rough terrains. In addition, a foothold search algorithm that provides the valid foothold while maintaining a high traversability of the robot, is investigated and a gait selection algorithm is developed to help the robot avoid deadlock situations. To explain the algorithms, new concepts such as reachable area, stable area, potential search direction, and complementary kinematic margin are introduced, and the effectiveness of the algorithms is validated via simulations and experiments.     

A framework for the collective movement of mobile robots based on distributed decisions

A novel framework for the control of the collective movement of mobile robots is presented and analyzed in this article. It allows a group of robots to move as a unique entity performing the following functions: obstacle avoidance at group level, speed control and modification of the inter-robot distance. Its flocking controller is distributed among the robots, allowing them to move in the desired common direction and maintain a desired inter-robot distance. The framework is made up of different modules that modify the behavior of the group thus allowing different functions. They are based on consensus algorithms that allow the robots to agree on different parameters, taking into account which robot has more relevant information. New modules can be easily designed and incorporated into the framework in order to augment its capabilities. It can be easily implemented on any mobile robot capable of measuring the relative positions of neighboring robots and communicating with them. It has been successfully tested using 8 real robots and in simulation with up to 40 robots, demonstrating experimentally its scalability with an increasing number of robots.     

The effect of lutein supplementation on visual fatigue: A psychophysiological analysis

We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2 h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue.