长镜头在动画创作中的应用

长镜头是现代传媒艺术的产物,并随之发展而广泛利用,现已成为电影、电视、动画制作的重要表现手法。如何不断提高它在艺术创作中的使用效率,是摆在艺术创作者面前一个亟待解决的问题。笔者正是基于这种考虑,才以抛砖引玉的形式,来求得大家的共鸣。     

Recumbent vs. upright bicycles: 3D trajectory of body centre of mass,limb mechanical work,and operative range of propulsive muscles

Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations. Data collected at 50, 70, 90 110 rpm during stationary cycling were used to drive musculoskeletal modelling simulation and estimate muscle-tendon length. Results demonstrated that BCoM trajectory, confined in a 15-mm side cube, changed its orientation, maintaining a similar pattern across all cadences in both bicycles. RB displayed a reduced additional mechanical external power (16.1 ± 9.7 W on RB vs. 20.3 ± 8.8 W on NB), a greater symmetry on the progression axis, and no differences in the internal mechanical power compared to NB. Simulated muscle activity revealed small significant differences for only selected muscles. On the RB, quadriceps and gluteus demonstrated greater shortening, while biceps femoris, iliacus, and psoas exhibited greater stretch; however, aerodynamics still remains the principal benefit.     

Comparing para-rowing set-ups on an ergometer using kinematic movement patterns of able-bodied rowers

While numerous studies have investigated the biomechanics of able-bodied rowing, few studies have been completed with para-rowing set-ups. The purpose of this research was to provide benchmark data for handle kinetics and joint kinematics for able-bodied athletes rowing in para- rowing set-ups on an indoor ergometer. Able-bodied varsity rowers performed maximal trials in three para-rowing set-ups; Legs, Trunk and Arms (LTA), Trunk and Arms (TA) and Arms and Shoulders (AS) rowing. The handle force kinetics of the LTA stroke were comparable to the values for able-bodied literature. Lumbar flexion at the catch, extension at the finish and total range of motion were, however, greater than values in the literature for able-bodied athletes in the LTA set-up. Additionally, rowers in TA and AS set-ups utilised more extreme ranges of motion for lumbar flexion, elbow flexion and shoulder abduction than the LTA set-up. This study provides the first biomechanical values of the para-rowing strokes for researchers, coaches and athletes to use while promoting the safest training programmes possible for para-rowing.     

100m优秀运动员体能分配的结构优化

通过对供能特点与体力分配、神经系统与体力分配和速度变化节奏对体能分配影响的分析,科学、合理的协调步频与步幅的关系是控制100m全程跑速度节奏的关键,从而为100m全程跑体能分配结构优化的模式构建提出了科学的理论依据。     

我国男子400m跑成绩与世界水平的差距及其对策研究

从能量类供应的特点来看，400m跑属于糖酵解代谢类型。由于认识的偏差，曾认为400m跑属于体能类中耐力性中跑项目，导致训练以速度耐力为主，速度为辅，影响了我国男子400m成绩的进一步提高。笔者认为400m训练应把速度和速度耐力放在同等重要地位，同时加强步幅训练的比重，重视力量素质及腰、腹肌力量的训练。这是我国男子400m缩短与世界先进水平差距的有效措施。     

跳远运动员助跑后阶段步长调整对踏板准确性的影响

采用文献资料、摄影、影片解析及对比分析等研究方法，从助跑最后几步的有关运动学参数入手，对跳远运动员后程助跑技术进行研究，认为运动员最后4步助跑步长调整直接影响踏板的准确性，过早调整对准确上板不利；第二标志增加了运动员的视觉刺激，影响助跑的连贯性；最后两步步长差值越小，准确上板的可能性越大；两腿均衡发展是准确助跑的一个关键因素。     

从几个基本数据看凯特的快跑能力和技术特点

本文对基普·凯特在800m跑预、决赛中，两次创造室内世界纪录的现场比赛录像进行了观测，着重从分段跑成绩、步长、步频、支撑阶段与腾空阶段的时间进行研究，分析了基普·凯特保持快节奏跑的技术特征。     

对步长和步频合理组合与100m跑成绩相关性的研究

日本田联和国际田联生物力学课题组记录了在东京举行的第3届世界田径锦标赛男子100m决赛8名运动员包括速度、步长、步频在内的许多数据。作者通过对数据资料的分析处理,发现导致刘易斯等运动员的速度呈双高峰期的原因是步长和步频的合理组合模式遭到破坏,并得到如下结论:保持合理速度比追求最大速度更能提高100m运动成绩;建立步长和步频的合理组合模式是提高运动成绩的有效途径。     

不同水平女子运动员50m自由泳途中游速度和划频、划幅变化的研究

采用游泳比赛现场测试方法,对女子运动员50 m自由泳途中游每10 m游泳速度和划频、划幅技术进行了测试。结果显示:50 m自由泳速度的下降与运动水平无关,速度的下降主要是由划频的下降造成的。因此,要求高水平短距离游泳运动员不仅应具备高水平的速度能力同时应具有保持高速度运动的能力。     

Improper use of linear reasoning: An in-depth study of the nature and the irresistibility of secondary school students' errors

Several recent ascertaining studies revealed a deep-rooted and almost irresistible tendency among 12–16-year old students to improperly apply the linear or proportional model in word problems involving lengths, areas and volumes of similar plane figures and solids. While these previous studies showed to what extent students' improper use of linear reasoning is affected by different characteristics of the task, it remained largely unclear what aspects of their knowledge base are responsible for the occurrence and strength of this phenomenon and how these aspects relate to other more general misconceptions and buggy rules identified in the literature. This paper reports an in-depth investigation by means of individual semi-standardised interviews aimed at analysing the thinking process underlying students' improper linear reasoning and how this process is affected by their mathematical conceptions, beliefs and habits. During these interviews,students' solution processes were revealed through a number of well-specified questions by the interviewer with respect to one single non-linear application problem, as well as through their reactions to subsequent kinds of cognitive conflict. The interviews provided a lot of information about the actual process of problem solving from students falling into the ‘linearity trap’ and the mechanism behind it. Although some students seem to really ‘believe’ that quantities are always linked proportionally, their improper use of linearity often results from superficial and intuitive reasoning, influenced by specific mathematical conceptions, habits and beliefs leading to a deficient modelling process. This revised version was published online in July 2006 with corrections to the Cover Date.