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Modeling of bond behavior of hybrid rods for concrete reinforcement
Nanni, Antonio,Liu, Judy Techno-Press 1997 Structural Engineering and Mechanics, An Int'l Jou Vol.5 No.4
Fiber reinforced plastic (FRP) rods are used as reinforcement (prestressed or not) to concrete. FRP composites can also be combined with steel to form hybrid reinforcing rods that take advantage of the properties of both materials. In order to effectively utilize these rods, their bond behavior with concrete must be understood. The objective of this study is to characterize and model the bond behavior of hybrid FRP rods made with epoxy-impregnated aramid or poly-vinyl alcohol FRP skins directly braided onto a steel core. The model closely examines the split failure of the concrete by quantifying the relationship between slip of the rods resulting transverse stress field in concrete. The model is used to derive coefficients of friction for these rods and, from these, their development length requirements. More testing is needed to confirm this model, but in the interim, it may serve as a design aide, allowing intelligent decisions regarding concrete cover and development length. As such, this model has helped to explain and predict some experimental data from concentric pull-out tests of hybrid FRP rods.
Experimental bond behavior of hybrid rods for concrete reinforcement
Nanni, Antonio,Nenninger, Jeremy S.,Ash, Kenneth D.,Liu, Judy Techno-Press 1997 Structural Engineering and Mechanics, An Int'l Jou Vol.5 No.4
Fiber reinforced plastic (FRP) rods provide certain benefits over steel as concrete reinforcement, such as corrosion resistance, magnetic and electrical insulation, light weight, and high strength. FRP composites can be combined with a steel core to form hybrid reinforcing rods that take advantage of properties of both materials. The objective of this study was to characterize the bond behavior of hybrid FRP rods made with braided epoxy-impregnated aramid or poly-vinyl alcohol FRP skins. Eleven rod types were tested using two concrete strengths. Specific topics examined were bond strength, slip, and type of failure in concentric pull-out tests from concrete cubes. From analysis of identical pull-out tests on both hybrid and steel rods, information on relative bond strength and behavior were obtained. It is concluded that strength is similar but slip in hybrid rods is much higher. Hybrid rods failed either by pull-out or splitting the concrete block (with or without yielding of the steel core). Experimental data showed consistency with similar test results presented in the literature.
Nanny Kim 고려대학교 민족문화연구원 2014 Cross-Currents Vol.- No.13
In the official records, copper mines in the southwest of the Qing empire seem to suddenly appear in the late 1730s. In part, this impression is an effect of government attention. Copper, which was the most important metal for casting cash coins, became a pressing concern when imports of Japanese copper dwindled. The government responded by developing domestic resources. Seemingly overnight, Yunnan mines reached impressive levels of productivity and replaced imports. For several decades, the Tangdan mines in northeastern Yunnan supplied most of the copper consumed by the centrally important metropolitan mints. The sudden boom is remarkable and not entirely plausible. This article reassesses the history of Qing-period mining by examining a particular case study. It explores an essay about the Dongchuan earthquake of 1733 that provides a glimpse at the empire’s leading copper mines on the eve of the recorded boom. A close analysis of figures, mining technology, and organizational structures reveals that the mines had been developed by mining entrepreneurs and migrant workers for a considerable period of time outside government attention, operating in a gray zone of unlicensed exploitation. The studied case permits a new assessment of the role of the state and of nonstate players in the industry. Moreover, it throws a new light on the image of Qing society and economy created by the official emphasis on agriculture and the actual role of the nonagrarian sector.
Student and Teacher Preferences in Written Corrective Feedback
Alexander Nanni,Douglas A. Black 아시아영어교육학회 2017 The Journal of Asia TEFL Vol.14 No.3
For the most part, teachers and students agree that WCF is an important part of language learning (Corpuz, 2011); however, there is disagreement about the type of feedback that best facilitates students’ development. This disagreement extends both to the typology of WCF (i.e., direct, indirect, metalinguistic) and to the question of whether feedback should be comprehensive or focus on specific error types (Ellis, 2009). Many studies (e.g., Biber, Nekrasova, & Horn, 2011; Kang & Han, 2015) have investigated the effectiveness of WCF in improving writing; however, few researchers have studied teachers’ and students’ perceptions of the usefulness of feedback on specific categories of error. These perceptions impact instruction, particularly when they are not aligned. Students may believe that their teachers have failed to address the most crucial errors in their writing. Conversely. teachers may believe that students have disregard important feedback. This report describes an investigation of preferences in WCF, examining the importance that teachers and students ascribe to five categories of feedback: content, grammar, organization, spelling, and vocabulary. These categories encompass the major areas of WCF. Based on a review of the literature and the state of language education in Thailand, we hypothesized that teachers’ and students’ preferences regarding WCF in the five areas studied would differ.
Crack source location by acoustic emission monitoring method in RC strips during in-situ load test
Shokri, Tala,Nanni, Antonio Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.1
Various monitoring techniques are now available for structural health monitoring and Acoustic Emission (AE) is one of them. One of the major advantages of the AE technique is its capability to locate active cracks in structural members. AE crack locating approaches are affected by the signal attenuation and dispersion of elastic waves due to inhomogeneity and geometry of reinforced concrete (RC) members. In this paper, a novel technique is described based on signal processing and sensor arrangement to process multisensory AE data generated by the onset and propagation of cracks and is validated with experimental results from an in-situ load test. Considering the sources of uncertainty in the AE crack location process, a methodology is proposed to capture and locate events generated by cracks. In particular, the relationship between AE events and load is analyzed, and the feasibility of using the AE technique to evaluate the cracking behavior of two RC slab strips during loading to failure is studied.
Zhang Cheng,Nanni Huang 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.2
Letter of Credit (L/C) is currently a very popular international settlement method frequently used ininternational trade processes amongst countries around the globe. Compared with other international settlementmethods, however, L/C has some obvious shortcomings. Firstly, it is not easy to use due to the sophisticatedprocesses its usage involves. Secondly, it is sometimes accompanied by a few risks and some uncertainty. Thus,highly efficient methods need to be used to assess and control these risks. To begin with, FAHP and KMVmethods are used to resolve the problem of incomplete information associated with L/C and then, on this basis,Bayesian game theory is used in order to make more scientific and reasonable decisions with respect tointernational trade.