从信息学角度看人类文化--论文化的实质及其进化

世界已经进入信息文化时代，信息学却很少深入探讨文化问题。从信息学角度研究文化是社会发展和信息学自身发展的需要。从信息学角度考察文化，提出了基于信息学的文化的全新定义，并以信息的各方面特征为统一线索，论述了文化进化的过程、特征、规律。     

鞍马技术训练对策探讨

通过对鞍马技术训练的对策的分析，旨在进一步提高鞍马技术水平，促进鞍马向高难度、巧编排、妙连接的方向发展，并应根据世界体坛的变化和国内的具体情况及时调整、修改、补充、完善训练计划，以吻合新规则的实施     

国内U-21足球守门员防守技术运用情况的调查研究

运用临场观察统计法、访谈法等对国内U-21足球守门员主要防守技术的运用情况进行了调查统计与归纳分析,研究表明,U-21守门员的失球主要表现在预判和反应能力上,对射门的观察的及时性和思维的准确性不足,导致反应慢、选位差和接球脱手,动作易失误;U-21守门员的出击失误主要表现为对出击时机的把握性上,判断和观察意识的薄弱,势必导致其施展争夺或截击球的技术动作的被动,强干扰状态下失误增多;要重视和加强青少年守门员的反应和场上意识的培养.对提高年轻守门员的反应和意识水平重视不够,就难以有高质量的守门员后备人才出现.     

图书馆计算机应用模式选择

目前我国图书馆的计算机应用模式主要有6种,其中微机多用户、微机局域网和小型机系统模式,在我国高校图书馆具有较大的实际可行性。图书馆可以根据本馆的藏书量和业务开展情况,选择适宜的应用模式。文章还在图书馆规模划分的基础上,探讨了不同规模图书馆的模式选择问题,并提出了倾向性意见。     

北京大学图书馆隆重庆祝建馆100周年

2002年，北京大学图书馆欣逢建馆一百周年。北京大学图书馆在盛世金鹰等企业的赞助下，经过精心的策划准备，举行了一系列庆祝活动。10月23日上午，庆祝北京大学图书馆建馆一百周年大会在北京大学英杰交流中心举行。德高望重的北大名师季羡林、侯仁之先生，教育部副部长袁贵仁，文化部副部长赵维绥，新闻出版署副署长柳斌杰，国家图书馆馆长任继愈，国家自然科学基金委主任陈佳洱院士，北京大学党委书记闵维方、副书记赵存生，北大图书馆馆长戴龙基，来自海内外的百余名著名大学图书馆馆长，北京大学各院系领导以及图书馆全体馆员共500余人…     

低氧训练对大鼠骨骼肌乳酸脱氢酶和苹果酸脱氢酶活性的影响

建立用低压氧舱模拟高原４ ０００ ｍ 低氧环境的动物训练模型,观察３周低氧训练和低氧生活及返回平原复氧训练２周对大鼠腓肠肌乳酸脱氢酶（ＬＤＨ）和苹果酸脱氢酶（ＭＤＨ）活性的影响。结果表明高原训练能提高大鼠骨骼肌ＬＤＨ 和ＭＤＨ 活性,但返回平原后ＬＤＨ活性显著性下降,ＭＤＨ活性则有再提高的趋势。     

青春突增期不同发育类型男女生体型特征的研究

处在青春发育期的男、女孩骨龄的变化幅度明显大于生活年龄。同年龄、同性别、不同发育类型组间男、女生的身高、体重、皮下脂肪量、肱骨远端宽、股骨远端宽、上臂紧张围、小腿围、体脂％ 和瘦体重等形态指标存在非常显著性差异,其变化规律与发育程度一致,均值依次为早发育＞ 正常发育＞ 晚发育。此外,三种不同发育类型男孩和女孩的体型特点为：早发育男孩和女孩的体型明显偏向内胚型、正常发育男孩和女孩的体型为中胚型、而晚发育男孩和女孩的体型则偏向外胚型     

Estimating the time-dependent reliability of aging structures in the presence of incomplete deterioration information

The performance of an aging structure is commonly evaluated under the framework of reliability analysis, where the uncertainties associated with the structural resistance and loads should be taken into account. In practical engineering, the probability distribution of resistance deterioration is often inaccessible due to the limits of available data, although the statistical parameters such as mean value and standard deviation can be obtained by fitting or empirical judgments. As a result, an error of structural reliability may be introduced when an arbitrary probabilistic distribution is assumed for the resistance deterioration. With this regard, in this paper, the amount of reliability error posed by different choices of deterioration distribution is investigated, and a novel approach is proposed to evaluate the averaged structural reliability under incomplete deterioration information, which does not rely on the probabilistic weight of the candidate deterioration models. The reliability for an illustrative structure is computed parametrically for varying probabilistic models of deterioration and different resistance conditions, through which the reliability associated with different deterioration models is compared, and the application of the proposed method is illustrated.     

Squeal noise in hydraulic poppet valves

The poppet valve is a fundamental component in fluid power systems. Under particular conditions, annoying “squeal” noises may be generated in hydraulic poppet valves. In the present study, the frequency spectrum of the squeal noise is obtained by analyzing the sampling data from the accelerometer mounted on the valve body. It is found that the flow velocity, pressure, and structural parameters have crucial effects on the properties of squeal noise, especially frequency. Larger valve chamber volume or lower backpressure leads to lower fundamental frequency of the squeal noise. An explanation for the squeal noise, as a result of Helmholtz resonance, is suggested and proved by experimental results.