Results 21 to 30 of about 28,191 (167)
Behavior of a Flexspline in Harmonic Drive [PDF]
, 1900 谐波齿轮传动是利用柔性工作构件的弹性变形波进行运动或者动力传递的一种新型传动方式，因其具有体积小、重量轻、精度高、单级传动比大、承载能力高等诸多优点，在航空航天、机器人、数控机床等领域得到了广泛的应用。柔轮作为谐波齿轮传动的关键构件很大程度上影响了谐波齿轮传动的承载能力、使用寿命等。柔轮为弹性薄壁件，在交变载荷作用下易导致齿面磨损和疲劳断裂。柔轮强度、变形与应力分析对谐波齿轮传动过程中的疲劳断裂评估及传动性能研究具有重要的意义。 本文首先根据已知参数、实际工况和谐波齿轮传动啮合参数选取原则 ...
刘淳剑
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Conservation Biology, EarlyView.Abstract Achieving global conservation policy goals requires the ability to set and measure progress toward science‐based targets for biodiversity. The species threat abatement and restoration (STAR) metric was developed to enable actors to set science‐based targets for species.
Louise Mair +17 more
wiley +1 more source
The Experimental Study on Flow Boiling Heat Transfer of Working Fluid R245fa in Horizontal Tube [PDF]
, 2017 设计了管内沸腾换热系数及总传热系数测定试验台架,对R245fa工质在内径6 mm水平光管内的流动沸腾换热特性进行试验研究。测试质流密度为50 ~; 150 kg /(m~2·s),工质蒸发温度为50, 60和70℃。结果表明:; 随着工质含汽率的增加,R245fa的流动沸腾换热系数呈先增大后降低趋势。对于304不锈钢套管式换热器,烟气与R245fa工质进行换热的总传热系数; 约在40 ~ 65 W/(m~2·K) 。A bench - scale facility was designed for ...
刘美丽 +4 more
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International Journal of Applied Linguistics, EarlyView.ABSTRACT Although the use of AI technologies (e.g., chatbots and automated writing evaluations (AWE)) has gained considerable attention in language learning fields in recent years, how AI technologies have been designed and implemented in language learning education, as well as their effectiveness, is understudied.
Shen Qiao +2 more
wiley +1 more source
The Development and Validation of the Chinese Vocabulary Levels Test
International Journal of Applied Linguistics, EarlyView.ABSTRACT In response to the increasing need for effective Chinese vocabulary assessments, this study developed the Chinese Vocabulary Levels Test (CVLT), a test designed for intermediate‐level Chinese as a second or foreign language (CSL/FL) learners, based on the vocabulary lists (levels 4–6) from the Chinese Proficiency Grading Standards for ...
Shiwei Qi, Ailan Fu
wiley +1 more source
International Journal of Applied Linguistics, EarlyView.ABSTRACT Collaborative writing has attracted increasing attention in English as a Foreign Language (EFL) instruction due to its potential to enhance learners’ writing competence. However, few studies have examined the comparative effects of collaborative versus independent writing on EFL learners’ individual performance, especially in higher‐order ...
Ting Huang, Chenze Wu, Wenkang Zhang
wiley +1 more source
基于登记/注册研究的随机对照试验 Registry-Based Randomized Clinical Trials
Zhongguo cuzhong zazhi, 2022 基于登记/注册研究的随机对照试验是一种利用现有的高质量登记/注册平台进行病例记录、数据收集、随机化应用以及随访的临床试验。本文简要介绍基于登记/注册研究的随机对照试验的基本概念、历史渊源、设计思路与传统随机对照试验的比较、适用场景、案例解读、统计方法及报告规范等内容，以期帮助临床研究者认识了解、掌握此类研究设计。 Abstract: A registry-based randomized controlled trial (RCT) is a clinical trial utilizing ...
周齐，杨凯璇，姜英玉，谷鸿秋
doaj +1 more source
Basic income trials and the politics of scale: A research agenda
Policy Studies Journal, EarlyView.Abstract The growing popularity of basic income has led to extensive trials of the policy in numerous settings across the world. However, analysis of the politics of basic income, and in particular the political dynamics preceding and resulting from trial programs, lags. In response, we propose a research agenda that uses political scale to investigate
Jurgen De Wispelaere +2 more
wiley +1 more source
Gaoya dianqi, 2012 到目前为止,已有大量文献介绍了各类绝缘子的人工污秽试验结果,少有文献涉及交直流人工污秽试验电源的特性试验研究。特高压交直流污秽试验电源电压高,电源特性实现难度大,因此需要对电源特性进行试验研究,探索交直流污秽电源的参数特性及其规律。昆明特高压实验室污秽实验室开展了一系列特高压交直流污秽电源的特性试验研究。研究成果一方面为人工污秽试验的理论研究和工程应用提供依据,同时为待建或已建交直流污秽试验电源的特性试验研究提供参考。文中说明了污秽交直流试验电源的工作原理和性能要求 ...
丁薇 +4 more
doaj
Wear Resistance of Cast Iron Remelted by Non-Transferred Laminar Plasma Jet [PDF]
, 2004 对在大气压条件下用非转移弧层流等离子体射流熔凝强化处理的W-Mo-Cu铸铁表面,采用光学显微镜、显微硬度计、磨损试验机、扫描电镜等,观察和测试了熔凝试样的表面层组织、硬度、耐磨性和磨损形貌.结果表明,熔凝后铸铁表面为初晶渗碳体和莱氏体组成的过共晶组织 ...
潘文霞, 费群星, 马维
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