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采用问卷调查法、专家访谈法调查访谈了在第六届城运会比赛网球项目成绩排名前五名省市,包括湖北、河南、天津、安徽、北京等的一线优秀网球运动员和教练员,并运用单因素方差分析与独立样本T检验对我国青少年男子网球运动员的身体机能特征中的循环机能指标进行深入而系统的分析,得出不同等级网球运动员身体机能特征中的循环机能中有显著差异指标,旨在为促进我国网球运动后备人才选材以及建立机能评价标准提供可操作性的依据。 相似文献
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为解决河南大峪沟煤业集团有限责任公司华泰煤矿工作面上隅角瓦斯浓度超限的问题,在12采区12030和12070工作面下部开展底板抽放巷、底板抽放巷穿层钻孔、并对底板抽放巷穿层钻孔进行水力冲孔卸压增透等措施。通过分析底抽巷区域消突工程可以从物理力学性质上增大二1煤层的孔隙率、透水性和润湿性。较大程度的提高了瓦斯抽采率,较好的解决了工作面和上隅角瓦斯浓度过大,为多构造突出矿井的安全高效生产提供了实践经验和理论参考。 相似文献
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通过分析"银期转账系统"中的多用户在线模块(简称MUOM)的处理性能,并进一步优化MUOM的处理效率.通过研究MUOM的MVC框架,找出其效率瓶颈,并提出新的技术改进方案,重新优化MUOM模块,最后经过仿真实验得出改进后的性能测试结果及结论. 相似文献
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Cun-jian MIAO Jin-yang ZHENG Xiao-zhe GAO Ze HUANG A-bin GUO Du-yi YE Li MA 《浙江大学学报(A卷英文版)》2013,14(1):31-37
Cold-stretched pressure vessels from austenitic stainless steels(ASS) are widely used for storage and transportation of liquefied gases,and have such advantages as thin wall and light weight.Fatigue is an important concern in these pressure vessels,which are subjected to alternative loads.Even though several codes and standards have guidelines on these pressure vessels,there are no relevant design methods on fatigue failure.To understand the fatigue properties of ASS 1.4301(equivalents include UNS S30400 and AISI 304) in solution-annealed(SA) and cold-stretched conditions(9% strain level) and the response of fatigue properties to cold stretching(CS),low-cycle fatigue(LCF) tests were performed at room temperature,with total strain amplitudes ranging from -.4% to -.8%.Martensite transformations were measured during the tests.Comparisons on cyclic stress response,cyclic stress-strain behavior,and fatigue life were carried out between SA and CS materials.Results show that CS reduces the initial hardening stage,but prolongs the softening period in the cyclic stress response.Martensite transformation helps form a stable regime and subsequent secondary hardening.The stresses of monotonic and cyclic stress-strain curves are improved by CS,which leads to a lower plastic strain and a much higher elastic strain.The fatigue resistance of the CS material is better than that of the SA material,which is approximately 1?03 to 2?04 cycles.The S-N curve of the ASME standard for ASS is compared with the fatigue data and is justified to be suitable for the fatigue design of cold-stretched pressure vessels.However,considering the CS material has a better fatigue resistance,the S-N curve will be more conservative.The present study would be helpful in making full use of the advantages of CS to develop a new S-N curve for fatigue design of cold-stretched pressure vessels. 相似文献
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Inspiratory muscle fatigue may occur in as little as 6 min during high-intensity spontaneously breathing exercise. The aims of this study were to determine whether inspiratory muscle fatigue occurs during swimming exercise and whether inspiratory muscle strength differs between the supine and standing body positions. Seven competitive swimmers were recruited to perform a single 200 m front-crawl swim, corresponding to 90-95% of race pace. Inspiratory muscle strength was measured at residual volume using a hand-held mouth pressure meter that measured maximal inspiratory pressure in the upright and supine positions. At baseline, maximal inspiratory pressure in the supine position was significantly lower than maximal inspiratory pressure in the upright position (112±20.4 and 133±16.7 cmH2O, respectively; P?0.01). Post-exercise maximal inspiratory pressure in the supine position (80±15.7 cmH2O) was significantly lower than baseline maximal inspiratory pressure in the supine position (P?0.01). The results indicate that a single 200 m front-crawl swim corresponding to 90-95% of race pace was sufficient to induce inspiratory muscle fatigue in less than 2.7 min. Furthermore, although diaphragm muscle length is optimized when supine, our results indicate that the force output of the diaphragm and inspiratory accessory muscles is greater when upright than when supine. 相似文献
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基于压力管理的图书馆人力资源管理平衡策略——借鉴全球知名大企业的管理经验 总被引：1，自引：0，他引：1
本文从组织层面分析了馆员压力的有效管理,并借鉴一些全球知名大企业的压力管理策略,从企业管理角度提出了图书馆人力资源管理平衡的组织面策略。 相似文献
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INTRODUCTIONWindenergyofabout2.531011Wavailableeverywhere,especiallyincoastalregions,deserts,grasslandsandcountrysideareasinChina,ispol-lutionfreeandrenewable(Xueetal.,2001).Useofwindenergycanimprovethelivingandworkingconditionsofpeople.Themanyelectricitygen-eratorsdrivenbywindpowerallovertheworldefficientlyextractwindenergyforconversionintoelectricalenergy.Manyregions,suchascountry-sideandruralareashavehighdensityofwindpower,buttheconditionsarenotgoodenoughforestablishingahighelectricpo… 相似文献
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杨素琴 《雁北师范学院学报》2004,20(2):11-13
用两种方法对平衡辐射场的压强进行了探讨.得到两个结沦:(1)平衡辐射场内部的压强与腔壁受的 压强相同:(2)平衡辐射场的压强只与系统平衡时的温度有关,与其它性质无关. 相似文献