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1.
地下洞,指的是自然环境中天然的温泉流出的水口,二指农田灌溉的专用水道,人们习惯称之为地下洞。每年入冬以后,苏北里下河地区河水进入枯水期,多数河沟近乎干涸,滞留在草里越冬的鱼群都难逃脱非法电鱼人之手。此间要想钓小水域很难有一席之地。有兴趣的钓友不妨到地下洞去一试身手,不过冬钓地下洞也是有技巧可言的。选洞要求洞口要有一定深度的水位。洞道长度要在20米以上,直径在2米左右,当然是越大越好。这些环境秋种时还在通水,现在洞内常遗有一半或大半深度的水位,里面通气透光良好,隐蔽性强。只有具备了这些条件,鱼才有可能在洞里藏身。… 相似文献
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本文针对某实际工程中边坡位置处桥墩的抗震性能进行了一般性讨论。采用简化的计算方法,对规则桥梁的桥墩进行内力计算,该方法可供校核有限元方法的计算结果。边坡处桥墩高度变化大导致桥墩抗推刚度之间差异明显,支座的水平剪切刚度对降低桥墩的组合抗推刚度作用明显。 相似文献
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洞石是一种新兴的进口建筑装饰石材,其主要特点是碳酸盐矿物在沉积过程中有气体存在,形成很多孔洞,是一种多孔的岩石。孔洞问题是洞石的天然特征,也是其安全性能的弱点。经过合理的设计、施工、使用能够很好的控制石材工程的质量和安全。 相似文献
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反演分析是主要利用监测资料的正分析成果,应用数学方法反求大坝及其基础的热力学参数,可以评价计算模型和结果的精度,从而提高计算成果的准确性。基于分布式光纤的测温优势,结合西南某施工期特高拱坝河床坝段,通过在其特殊浇筑仓距表层下60cm内不同深度处埋设分布式光纤测温,并对其测温结果分别取平均值,从而反求大坝混凝土导热系数。计算结果表明,比大坝设计初期拟定值略高,符合实际情况,其结果更加真实可靠。 相似文献
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一般工民建中的民用住宅、办公楼和厂房建筑,桥梁堤坝等建筑都是由混凝土以及钢筋混凝土完成的,它不仅是工程建设的基本组成,更是保证工程建筑物质量的关键因素。混凝土施工的技术水平和实际施工能力,以及其本身的质量都是影响其施工质量的关键,本文主要分析建筑工程建设过程中混凝土施工的相关问题,总结出一些质量控制的方法,以此实现强化工程质量的目的。 相似文献
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随着我国城市化速度的加快,给排水工程在市政建设中占据着越来越重要的地位,排水施工技术反映了一个国家的地下施工水平。当前,我国城市人口剧增、车流量大,对道路的通行能力要求高,因此给排水施工时必须考虑到这一点。传统的开槽拉管技术已不能满足这一需求,我们有必须实施非开挖拉管技术,减少施工过程中对城市的交通、环境等造成影响。本文将从非开挖拉管技术的概述、非开挖拉管技术的优点、非开挖拉管技术的具体应用等方面来具体阐述。 相似文献
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岩心钻探是当前获取地下地质资料最为完成及最为直接的方法,尤其在深部探测工程中具有重要意义.从当前来看,常规的绳索取心技术具有较低的钻进效率,且刻取岩石的表面积较大,制约了其推广应用.为了充分发挥绳索取心技术的优势,创新一种新的岩心钻探方法——绳索取心液动潜孔锤.本文特对绳索取心液动潜孔锤的应用做详细探讨,以望对该技术有更为全面的了解. 相似文献
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弧垂检测是保证架空输电线路安全运行的重要措施.传统的手工计算弧垂的方法不仅计算量大,而且容易出错;现有计算机技术计算弧垂的方法虽然准确度较高,但需要复杂的公式和考虑众多因素(如导线温度、张力、传输容量等),在工程应用中给现场人员带来不便,难以推广应用.为此,提出一种基于图像识别技术的架空线弧垂计算方法,以悬链线模型为基础提取部分段曲线的独立状态参数,还原完整架空线并计算其弧垂.同时,基于Matlab GUI开发了一款实用的弧垂测量系统,并通过实际工程测试结果表明,该系统数据采集方式简单、运算速度快,结果展示和输出方便,既能满足工程的精度要求,又具有较高的实用性,是提高工程现场作业人员工作效率的实用应用工具. 相似文献
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为了尾矿库安全生产,对尾矿坝稳定性影响因素进行分析,针对具体的工程实例依据相关规范结合勘察资料,采用Fellenius、Bishop等稳定性计算方法对某尾矿坝抗滑稳定性分析,得出了在正常水位、洪水水位和特殊水位条件下该坝的稳定性计算结果。 相似文献
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This study examined the effect of carbohydrate ingestion on metabolic and performance-related responses during and after a simulated 1h cycling time trial. Eight trained male cyclists (VO 2 peak = 66.5ml kg -1 min -1 ) rode their own bicycles mounted on a windload simulator to imitate real riding conditions. At a self-selected maximal pace, the cyclists performed two 1h rides (separated by 7 days) and were fed either an 8% carbohydrate or placebo solution. The beverages were administered 25 min before (4.5ml kg -1 ) and at the end (4.5ml kg -1 ) of the ride. With carbohydrate feeding, plasma glucose tended (P = 0.21) to rise before the time trial. Compared with rest, the plasma glucose concentration decreased significantly (P < 0.05) at the end of both rides, with no statistically significant difference being observed between treatments. Thereafter, plasma glucose increased significantly (P < 0.05) at 15 and 30 min into recovery, and was significantly higher at 30 min during the carbohydrate trial compared with the placebo trial. No significant changes in plasma free fatty acids were observed during the ride. However, a significant increase (P < 0.05) in free fatty acids was found at 15 and 30 min into recovery, with no difference between trials. Mean power output was significantly (P < 0.05) greater during the carbohydrate compared with the placebo trial (mean - S.E.: 277-3 and 269-3W, respectively). The greater distance covered in the carbohydrate compared with the placebo trial (41.5-1.06 and 41.0–1.06km, respectively; P < 0.05) was equivalent to a 44s improvement. We conclude that pre-exercise carbohydrate ingestion significantly increases endurance performance in trained cyclists during a 1h simulated time trial. Although the mechanism for this enhancement in performance with carbohydrate ingestion cannot be surmised from the present results, it could be related to a higher rate of carbohydrate oxidation, or to favourable effects of carbohydrate ingestion on the central component of fatigue. 相似文献
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Roy J. Shephard 《Journal of sports sciences》2013,31(7):603-620
The biology and medicine of rowing are briefly reviewed. Effort in a 2000 -m race is about 70% aerobic. Because the boat (and in some instances a cox) must be propelled, successful competitors are very tall, with a large lean mass and aerobic power. Large hearts may lead to erroneous diagnoses of a cardiomyopathy. Large respiratory minute volumes must be developed by chest muscles that are also involved in rowing. The vital capacity is typically large, and breathing becomes entrained. Expiration cannot be slowed relative to inspiration (as normally occurs at high rates of ventilation) and the limiting flow velocity may be reached, with the potential for airway collapse. Performance is strongly related to the power output at the ‘anaerobic threshold’, and lactate measures provide a guide to an appropriate intensity of endurance training. Peak blood lactate levels are higher in males (commonly 11–19 mmol·l -1 and occasionally as high as 25 mmol·l -1) than in females (9–11 mmol·l -1), probably because males have a greater muscle mass in relation to blood volume. The skeletal muscles are predominantly slow twitch in type, developing an unusual force and power at low contraction velocities. Many rowers have a suboptimal diet, eating excessive amounts of fat. Lightweight rowers also have problems of weight cycling. Aerobic power and muscle endurance often change by 10% over the season, but such fluctuations can be largely avoided by a well-designed winter training programme. Injuries include back and knee problems, tenosynovitis of the wrist and, since the introduction of large blades, fractures of the costae. 相似文献
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Alan M. Nevill Roger L. Holder Andrew Bardsley Helen Calvert Stephen Jones 《Journal of sports sciences》2013,31(4):437-443
A regression analysis of competitors' tournament results in relation to their world rankings was proposed to identify the effect of home advantage in international ‘grand-slam’ tennis and ‘major’ golf tournaments. The results provided little evidence of home advantage in either the grand-slam tennis or the golf tournaments held in 1993. The only possible evidence of home advantage was found in the Wimbledon tennis and the US Open golf championships. Even these findings can be explained, at least partially, by (1) the availability of information concerning the low world rankings of the British tennis players competing at Wimbledon, and (2) selective entry, allowing only the world's top-ranked foreign golfers into the US open golf tournament. In both cases, the lower ranking home competitors have a greater opportunity to perform above their anticipated world rankings. Therefore, provided entry into tennis and golf tournaments is truly ‘open’ to both the host nation's representatives and foreign competitors alike, home advantage does not appear to be a major factor influencing the competitors' performance in such competitions. These findings may be explained by the relatively objective nature of the scoring systems used in tennis and golf, unlike the subjective influence of refereeing decisions on the results of team-games such as soccer. 相似文献
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许良 《体育科技文献通报》2011,19(2):1-4
基于1985、1995和2005年全国学生体质调研数据,对各时期我国城乡学生形态、机能、体能发展水平进行系统地定量研究,动态分析20年全国城乡学生体质发展的特点与规律。主要研究结果：（1）近20年城乡学生生长发育持续提前,城市学生各项形态指标生长水平高于乡村,身高城乡差距缩小,体重、胸围城乡差距加大;（2）城市学生肺活量水平高于乡村,城乡学生肺活量20年持续下降,前10年乡村学生下降快、后10年城市学生下降快;（3）乡村学生800m、1000m跑水平高于城市,城市女生50m跑、仰卧起坐水平高于乡村,其他素质城乡学生水平波动较大;（4）城市女生50m跑20年持续下降,城乡学生800m和1000m跑、城市学生50m×8往返跑20年加速下降,其他素质20年间有增有降发展极不平稳。 相似文献
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采用测量、问卷调查、数理统计等方法,分析定向运动学习前后对大学生身心健康的影响.结果经T检验和x2检验且表明：定向运动不仅能增强学生体质健康水平,而且有助于学生的情绪调节,增强自信心与创新意识,培养勇敢顽强的意志品质,建立良好的人际关系,能有效地促进学生身心健康发展.为了全面提高大学生整体素质,积极实践,构建定向运动课内外一体化教学模式,进行定向运动课程模块化教学,以满足学生的多元化需求. 相似文献
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重新认识体育的社会关联 总被引：3，自引：1，他引：2
体育与政治之间存在一个悖论，体育的发展与经济实力之间没有直线相关，体育与教育部分重叠，体育与宗教最为近缘，体育可借用科学手段，体育的艺术禀性日益明显，体育与养生反映着两种人生观。 相似文献
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本文在专家访谈、问卷调查、数理统计和文献资料分析的基础上,探析了上海社区体育竞赛参与者的特点、参与者对社区体育赛事运作管理的看法等问题。在此基础上从引进社区体育赛事的志愿者、整合社区体育赛事的各种资源、开发社区体育竞赛的无形资产、组建非营利性的专业团队、规范社区体育赛事的服务管理等方面提出了进一步满足上海社区居民日益增长的体育竞赛参赛需求的对策与措施。 相似文献
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对全面把握游泳训练环节的探讨 总被引：4，自引：0，他引：4
从系统观点出发,结合训练实践,对全面把握游泳训练环节进行探讨。认为应强化非智力因素在运动员多年训练中的作用,在育材全过程中不断选材,从整体上把握动态训练的全过程,把培养高水平运动员的整个过程置于一个严格的科学控制之下。 相似文献