探讨临时支撑卸载分析中的两种方法

目前在工程中，临时支撑卸载过程的分析和模拟主要有两种方法．利用这两种方法分别建立临时支撑卸载的有限元模型并在ANSYS中对这两个模型的卸载过程进行模拟和分析，从理论上和有限元分析结果上对这两种方法进行了探讨．     

技术创新网络中核心企业形成的三状态模型研究——基于企业间关系耦合的分析

技术创新网络的扩张与核心企业的成长相互促进,相互决定,形成了复杂的共生演化关系。以知识为基础的企业,必须在各个层次上构建网络,维护多层交互作用,加强与其他企业的合作。从企业间关系耦合的视角,分析了技术创新网络中核心企业的形成过程,提出技术创新网络中各结点企业间的技术合作是一种相互间的知识协同。研究发现,企业间技术交流的过程就是企业间知识匹配——知识流动——知识控制的过程,而技术创新网络中的企业结点也是通过这三种状态,使自身能力得到提升,进而影响到与其他结点的知识协同,并最终成长为核心企业。     

洞庭湖水质变化趋势的研究

以洞庭湖1992-2010年系列监测资料为依据,对洞庭湖19年的整体水质情况、富营养化状况以及主要污染指标进行了评价分析。结果表明:洞庭湖水质污染以氮磷污染为主,水体状况呈逐渐恶化的趋势,富营养化程度逐年加剧。2007年对洞庭湖流域进行整治后,水体中化学需氧量降低,但水体总氮和总磷浓度仍呈上升趋势,致使洞庭湖水体中叶绿素a含量和浮游植物数量显著增加。     

157Tm原子核三轴超形变的研究

根据TRS理论计算了^157Tm核的位能面，并预言了其三轴超形变的存在,计算的结果与文献上的结果符合得较好。     

The Many Faces of Practice Distribution in Motor Learning

Abstract

The purpose of this report was to introduce and validate a method to account for variable fatigue rates during cycle sprinting by incorporating decline from peak power (30%) as a test termination criterion. Fifteen healthy men performed three maximal sprint tests separated by 20 min (Bouts 1 and 2) and 48 hours (Bout 3). Power curves were analyzed for peak power, time to peak, time to fatigue (decline of 30% from peak), total work, total test time, fatigue rate, and the fatigue index. High test-retest reliability was demonstrated for all variables (R = 0.85–0.98). No significant differences were detected between variables (Bouts 1, 2 and 3; p > 0.01). Fatigue rates varied widely among participants (range = 24.7–65.4 W·s^-1), but the fatigue index was consistent (31.1 ± 0.16; mean ± standard error of measurement, range = 30.1–32.5%). Our data show that variable fatigue responses among participants are normalized to the percentage of decline from peak power by incorporating a relative fatigue cutoff criterion. This approach might inform mechanisms relating to short-term fatigue and recovery during consecutive sprint bouts.     

Contextual Interference Effects in Learning Three Badminton Serves

Abstract

This study investigated the generalizability of results of contextual interference effects by extending previous laboratory research to a field setting. Thirty female subjects (N = 30) learned three badminton serves in either a blocked (low interference), serial (mixed interference), or random (high interference) practice schedule. The subjects practiced the serves three days a week for three weeks. On the day following the completion of practice the subjects were given a retention and transfer test. Results replicated previous findings of contextual interference research by showing a significant group by block interaction between acquisition trials, retention, and transfer. The random group performed better on both retention and transfer than the blocked group. The significant trial block by contextual interference interaction also supports the generalizability of contextual interference effects, as posited by Shea and Morgan (1979), to the teaching of motor skills.     

Preparation and control of rapid, multisegmented responses in simple and choice environments

Research investigating the preparation and control of rapid, multisegmented responses typically has assumed complete programming of the response occurring prior to movement initiation and has made use of a simple reaction time (RT) paradigm. A notable exception is Rosenbaum's work which proposed the Hierarchical Editor (HED) model that is specifically directed toward the control of movements in the choice environment. The purposes of this study were to investigate the assumption of complete programming prior to movement initiation and to compare predictions of the HED model with other programming models. Three experiments are reported in which subjects were required to tap either one, two, or three plates as rapidly as possible in either a simple or choice RT situation. The results were very consistent in these experiments even with several modifications in apparatus and methodology. Of particular interest were effects of movement complexity on RT and movement time (MT) for the first and second segments of the movement (M1 and M2). Choice RT (CRT) results consistently showed no increases in RT as the number of movement segments increased but showed significant increases in M1. For simple RT situations, however, there were small but consistent increases in RT as well as increases in M1 with increases in the number of movement parts. For both CRT and SRT results, small but nonsignificant increases were noted for M2. These results provide evidence for incomplete programming prior to response initiation. Although the SRT data can be accommodated by Henry's theory, the HED model appears to offer the best overall fit for the results.