共查询到20条相似文献，搜索用时 125 毫秒
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自从会考的号令下了之后,中国传统教育界是展开了许多幕的滑稽的悲剧。
学生是学会考,教员是教人会考,学校是变成了会考筹备处。会考所要的必须教,会考所不要的就不必教,甚至于必不教。于是唱歌不教了,图画不教了,体操不教了,家事不教了,农艺不教了,工艺不教了,科学的实验不做了, 相似文献
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1.走着走着,就散了,回忆都淡了;看着看着,就累了,星光也暗了;听着听着,就醒了,开始埋怨了;回头发现,你不见了,突然我乱了。2.我的世界太过安静,静得可以听见自己的心跳。心房的血液慢慢流回心室,如此这般轮回。聪明的人喜欢猜心,也许猜对了别人的心,却也失去了自己的。傻 相似文献
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童年的一天,他在屋里玩,父亲沉默地坐在角落里。10分钟内,他做了11件事情:写了一个半字,画了一个没画成的苹果,看了几秒钟书,大叫了几声,踢翻了一个凳子,发呆半分钟,玩了三样玩具而且都扔到了门外,傻乎乎地唱了几句歌,欣赏了一下父亲没画完的画作,画了个女孩并哈哈大笑,最后发疯地叫了几声妈…… 相似文献
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王旭东 《教学月刊(中学下旬版)》2008,(3):48-50
"盼望着,盼望着,东风来了,春天的脚步近了","山朗润起来了,水涨起来了,太阳的脸红起来了",树绿起来了,小草青起来了,万物灵动起来了,我们的情思被惹起来了。朱自清眼里的春天"像刚落地的娃娃",像"花枝招展"的小姑娘,"像健壮的青年",是风和日丽、百花争艳、草长莺飞的季节。那你心目中的春天是怎样的, 相似文献
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嗨,亲爱的读者朋友们,大家好!在中国人的传统观念中,到了10月,基本上也算是到了年末了。想想也是,当收获的金秋过去之后,对于这一年而言,有什么更值得盼望的呢?大雁南飞了,这让人多少有些失落,可秋菊盛开了,那种芬芳更能沁人心脾!世间的一切总是这样,随着时光的流走,总要失去一些东西,也总会得到一些东西,要失去的很难挽回,但要得到的则可以去选择!同学们,随着一年年的过去,我们必将会不断地失去很多,而同时你又得到了什么?失去了童年你得到成长了吗?失去了依赖你得到自立了吗?失去了嫩弱你得到健壮了吗?失去了任性你得到责任了吗?失去了呵护你得到坚强了吗?失去了幼稚你得到智慧了吗?失去了童话你得到科学了吗……要失去的必定会失去,是否能得到的完全由你把握! 相似文献
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Hua ZHU Bo ZHUAN Jin-jun TAN Rong-hua HONG 《浙江大学学报(A卷英文版)》2008,9(3):410-415
This paper focuses on the heat transfer performance of semi-open heat pipe which is a new type of heat pipe. After analyzing its condensation heat transfer mechanisms theoretically, several semi-open heat pipes in different length ratios and upper hole diameters are studied experimentally and compared with the same dimensions closed heat pipes. Experimental results show that the heat transfer performance of semi-open heat pipe becomes better by increasing heat transfer rate. At the first transitional point, the heat transfer performance of semi-open heat pipe approaches the level of the closed heat pipe. It is suitable to choose upper small hole about 1 mm in diameter and length ratio larger than 0.6 for the semi-open heat pipe. 相似文献
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Separate type heat pipe heat exchangers are often used for large-scale heat exchanging. The arrangement of such a heat exchanger conveniently allows heat input to and output from the heat exchanger at remote locations. The traditional method of designing an ordinary HPHE (heat pipe heat exchanger) is commonly applied in the separate type exchanger design, but the calculations have to be carried out separately, which makes it very complicated. In this work, the ε-NTU (effectiveness-Number of Transfer Units) method was applied for optimization analysis of single-or multi-level separate type heat pipe heat exchangers. An optimizing formula for single-level separate type heat pipe heat exchangers was obtained. The optimizing principles of effectiveness-NTU and heat transfer rate by the equal distribution method for multi-level separate type heat pipe heat exchanger are presented. The design of separate type heat pipe heat exchangers by the optimizing method is more convenient and faster than by the traditional method. 相似文献
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蒙永寅 《南宁师范高等专科学校学报》2010,(5):29-31
采用试差法,参考换热器传热系数的大致范围,假设一个传热系数值,利用热量衡算和传热速率方程估算传热面积,初选换热器型号,最后校核传热系数和传热面积。 相似文献
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根据工程热力学、传热学、热工测试技术等关于换热器性能的基本测试原理和方法,结合现行的国家标准与规范要求,研发了水源热泵用换热器综合实验台.该实验台利用控制与测量技术,采用被测换热器与辅助换热器水侧部分的冷热负荷,通过水-水板式热交换器相互抵消方法,以及换热器两侧热平衡工作原理,即换热器水侧吸收或放出的热量与制冷剂侧放出或吸收的热量基本相等,可以实现在不同工况下对不同结构形式的R22蒸发器及冷凝器的换热性能和流体阻力性能进行全面的测试.为换热器的选型、优化设计和新产品开发提供依据和验证手段. 相似文献
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采暖的最终目的是利用物体间的换热规律,为室内人员营造一个舒适的热环境。而热环境的建立主要取决于房间内的换热状况。要对辐射采暖房间的换热计算进行探讨,建立辐射采暖房间的换热模型,列出反应房间换热状况的方程组;基于对建筑房间内换热特点的分析,对模型进行两种不同程度的简化。结合具体实例将各种换热模型的计算结果进行比较,得出简化的能综合反映房间换热状况的方程,计算求得的房间内的换热状况,大大简化辐射采暖房间的换热计算。 相似文献
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杨惠山 《泉州师范学院学报》2003,21(2):23-27
应用有限时间热力学理论，建立一类较普遍的不可逆斯特林热机模型，研究存在热阻、热漏、回热损失斯特林热机的优化性能，导出了热漏损失服从一般传热规律时热机的功率与效率间的优化关系，讨论了不同情况下热漏和回热损失对热机性能的影响，从而可为二热源热机的研制和优化设计提供新的理论指导。 相似文献
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任亚杰 《陕西理工学院学报(社会科学版)》2001,19(6):32-35
通过对热循环过程的特点进行分析 ,利用热力学基本定律 ,得出了热循环的效率只由系统在循环的每一子过程中与外界交换的热量决定 ,从而使热循环效率的计算方法得以简化 . 相似文献
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波形折流杆换热器的开发和工业化实验研究 总被引：1，自引：1，他引：1
The conventional heat exchanger with segmental baffles is prone to bring forth fluid-induced vibration of heat transfer tubes and increase the pressure drop of shell-side greatly at higher fluid flow velocity. In order to avoid the above defects, the ROD-baffle heat exchanger has been developed. However, its collocation of heat transfer tubes is conventionally in square, which leads to fewer heat transfer area per unit volume. Based on the ROD-baffle heat exchanger, a new type curve-ROD baffle has been developed, and an industrial investigation of the curve-ROD baffle heat exchanger with normal triangular collocation has been carried into execution. In this paper, two equations using the Reynolds number were acquired to predict the heat transfer coefficients of the shell-side and tubeside. The experimental results show that the shell-side heat transfer and pressure drop characteristics of the curve-ROD baffle heat exchanger are superior to those of the segmental baffle one. 相似文献
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Semi-open heat pipes were studied experimentally in this work. A new kind of semi-open heat pipe with fluid swirl backflow
was developed on the basis of the traditional semi-open heat pipe. Heat transfer characteristics during operation and start-up
of closed heat pipe traditional semi-open heat pipe and swirl flow semi-open heat pipe were investigated. The swirl orifice's
backflow effect on enhancing the working limitation was obtained. Heat exchangers or waste heat boilers made of swirl flow
semi-open heat pipes and semi-open heat pipes have been successfully used in high or variable gas temperature engineering
applications. 相似文献
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范玉东 《邢台职业技术学院学报》2005,22(1):70-72
在热电厂的供热机组已确定的条件下,供热方案的优劣就直接影响机组的供热能力、供热面积、热网投资、发电煤耗，影响热电厂的经济效益及热网供热系统的安全性、灵活性和可靠性。本文即是通过对铁煤集团热网工程的三环制供热方案及改造成低真空供热方案的比较分析,对热网工程中低真空供热的利弊进行了初步探讨。 相似文献