Book Review

Abstract

The mechanical responses (i.e. external contact forces and external power) of 25 elite rowers to a race-pace rowing protocol were investigated on the traditional fixed stretcher mechanism and the more recently introduced free-floating stretcher mechanism rowing ergometers. Using a Rowperfect rowing ergometer for both conditions, external contact forces at the handle, stretcher and sliding seat, as well as the displacements of the handle and stretcher, were recorded. The external power was calculated as the product of the force and velocity data from both the handle and stretcher. Significant differences (P < 0.05) between the two conditions for each mechanical parameter were observed. The fixed condition showed larger maximum values for forces and external power and average power throughout the rowing cycle. Moreover, rowing with the fixed mechanism generated higher inertial forces during the transition between the propulsion and recovery phases, especially at the catch of the cycle. The results suggest that: (i) muscular coordination may differ according to the stretcher mechanism used, which could have an impact on the physiological adaptations of muscles; and (ii) the free-floating mechanism may induce lower catch and maximum values for net joint forces and net joint moments that could decrease the risk of injury.     

对拉工作面的采区准备及回采系统的改进

介绍了在含水和瓦斯煤层中布置对拉工作面的可行性方案，从而扩大了对拉工作面的使用范围。     

亿级人像比对系统架构设计及优化

为满足公安机关大规模人像数据库的比对应用需求,提高人像比对系统应用规模和可用性,采用结构化开发方法,从应用层、数据库层、主机层、存储层等方面对人像比对系统进行模块化架构设计和优化。系统能够支撑15亿以上人像比对库容量,实现了全国范围的人像自动比对和纠错,提高了身份辨认速度。系统平均建模速度、平均比对速度和查重速度分别提升38%、41%和55%。优化后的人像比对系统在保证识别率高的同时能够快速处理海量数据,满足公安机关应用需求,有效解决了户口登记管理中的“错、重、假”问题。     

对外聘教师管理的若干思考

高职教育虽蓬勃发展,但其教育教学质量及社会认可度远未能达到理想状态,这是由于其自身发展的局限性、受国家经济实力的制约和自身可持续发展的需要,走专职教师和外聘教师相结合的道路将是师资队伍建设中的一个长期战略选择.本文从若干方面对高职院校外聘教师的积极意义进行了论述.同时,对如何加强对高职院校外聘教师管理提出建议.     

Modelling and analysis of alternative face guard designs for cricket using finite element modelling

In professional cricket, where bowlers can bowl balls that reach speeds of up to 160 km h^-1, effective head protection is vital. Current head protection equipment typically consists of a helmet with a high impact grade polypropylene shell, a high density EPS liner, and a metal face guard. Most of the weight in existing helmets is attributed to the steel grill used as the face guard. We present a virtual design approach to the development and evaluation of new face guards made from alternative materials. In particular, we investigate a face guard design for cricket made from polycarbonate rather than steel using an explicit dynamic finite element analysis (FEA) approach. The FEA model developed for this purpose incorporates the headform, helmet, polycarbonate face guard and the impacting ball. ABAQUS CAE was used for FEA. HyperMesh and SolidWorks were used to develop the geometric model. This work identifies appropriate modelling and simulation strategies, and key design attributes for the development of new face guards using alternative materials. A preliminary study shows that by using polycarbonates it is possible to reduce the mass of the face guard by 20%, thus contributing to greater comfort of the players without compromising their safety. The key criteria for reduction of ball deceleration by at least 25% at each test site were satisfied, with deceleration reduction values ranging from 44% to 87% from those due to ball impact with the bare head.     

基于肤色模型的人脸检测算法

在此研究了彩色图像中的人脸检测算法,在肤色模型方面讨论了肤色在不同的色彩空间中的表现,通过对一定数量的样本建立了一个图像库,选择色彩空间并建立了肤色模型,然后通过形态学等处理后得到候选区域。然后对候选区域使用特征脸的方法进行验证。通过这样的方法在保证了精度的同时克服了特征脸方法原有的搜索速度慢的特点。最后本文对所使用的方法作了一个总结并对下一步的工作进行了展望。     

工作面贯通测量技术实践与分析

本文根据某矿地质条件复杂,为保证首采工作面顺利贯通,通过对测量放线中导线的敷设、数据处理及其误差对贯通的影响与导线复测、平差和检核方法等问题进行分析研究,并成功应用于生产实践,确保了高精度安全贯通,为矿井按期投产奠定了基础。     

信息技术在采掘工作面资产运营管理中的应用

本文主要论述采掘工作面资产运营管理的现状,采用信息技术对采掘工作面资产运营各项内容进行管理的目的、意义和实现方法。采用的关键技术是利用powerbuilder数据窗口对象进行数据处理,实现报表统计,简化程序的复杂度。     

Face Threatening Acts and Negotiated Power

The study of politeness never rules out the consideration of context and power relationships. This article is a case study of one scene of classroom interaction from the movie Mone Lisa's Smile in order to demonstrate how the conventional power relationship in the classroom situation can be reversed by the outer economical and social forces.     

面子理论与大学英语作文批语研究

以Brown和Levinson提出的面子理论为基础,联系笔者从事大学英语教学的作文批语实例,探究英语作文批语对学生的面子维护情况以及批语对学生英语学习动力的影响。