挑选高等教育杰作

本文对《美国高等教育经典著作百种》的选编特点、主要类别与部分著作及其作者作了简明扼要的说明。     

Design and testing of a frictionless mechanical inerter device using living-hinges

In this paper a novel type of frictionless mechanical inerter device is presented, where instead of gears, motion of the flywheel is achieved using living-hinges. The design is a type of pivoted flywheel inerter inspired in part by the Dynamic Anti-resonant Vibration Isolator (DAVI) concept, which was first developed in the 1960s. Unlike the DAVI, it will be shown that the pivoted flywheel inerter has the advantage of producing balanced forces. Furthermore the use of living-hinges eliminates the need for gears or other frictional elements in the inerter mechanism. To demonstrate the utility of the new concept, a bench-top experiment was performed using a small-scale living-hinge inerter manufactured using polypropylene hinges. By estimating the experimental system parameters, the transmissibility results from the experiment could be compared to a mathematical model. These results showed that the living-hinge inerter provided an isolation effect of at least three orders of magnitude in terms of the maximum amplitude reduction from the uncontrolled system compared to that with the inerter added. Although friction was eliminated, the living-hinges did introduce additional damping, and this was found to correspond to an increase in the equivalent damping ratio for the uncontrolled system of 1.2%. It is shown that the living-hinge inerter developed in this paper fits all of the essential conditions required to be a practical inerter device. Furthermore, as it operates without mechanical friction, or fluid flow, it represents a new paradigm in experimental inerter technology.     

Institutional complementarities: The origins of experimentation in China’s plug-in electric vehicle industry

A vast literature on technology transitions within industries suggests that early phases of new technologies are marked by periods of intense experimentation, but we know little about the conditions under which these periods emerge. We apply inductive, grounded theory-building techniques to examine what prompts firms to experiment across one emerging technology platform—plug-in electric vehicles (PEVs)—in China. Triangulating annual vehicle make and model sales data from 2003 to 2016 (plus monthly data from 2010 to 2016); 112 English and Mandarin archival documents from industry, academic, and news outlets; and 51 semi-structured interviews with industry, government, and academic stakeholders, we develop four in-depth case studies. We find that in contrast to the innovation trajectories of multinational and Chinese arms of joint venture (JV) firms, independent domestic Chinese firms (those with no history of international JV partnerships) are undertaking significant experimentation across multiple levels—infrastructure, core system, subsystem, and component—of the emerging PEV technology platform. We propose the concept of “institutional complementarities” to describe how interactions among institutions—here the national JV regulation and local market support and subsidies—may have turned regional markets into protected laboratories, extending the incubation periods for independent domestic firm experimentation. While this diverse experimentation may be an important antecedent of technology transition, consolidation induced by national policy standardization or competitive pressure may be required for PEV innovations to scale beyond their early, protected regional markets.     

Pathogenic organization in science: Division of labor and retractions

Science is increasingly a team activity, and the size of the teams has been growing. At the same time, there are concerns about an increasing rate of pathologies in science. The growth of team science suggests the need to look beyond individual-level explanations and focus on organizational structures and institutional contexts to explain pathologies in science. Drawing on the literature on organizational pathologies, we argue that division of labor may be a key factor contributing to pathologies in science. Furthermore, we examine the effects of high-stakes incentives and of institutional corruption as additional predictors of scientific pathologies. Using retractions as an indicator of pathologies, and drawing on a matched sample of 195 retracted papers and 349 paired papers that were not retracted, we develop indicators of the division of labor in the team that produced a paper and find that the rate of retractions is higher as the division of labor increases (net of team size). Additionally, we find that high-stakes incentives and institutional corruption are also associated with increased retractions. We conclude with a discussion of the implications of these findings for science policy, in particular for organizing team science projects.     

Search tactics used in solving everyday how-to technical tasks: Repertoire,selection and tenacity

With greater access to computational resources, people use search to address many everyday challenges in their lives, including solving technology problems. Although there are now many useful ‘how-to’ resources online (especially videos on YouTube), it can still be difficult to identify, understand, and resolve certain kinds of technical problem. While research tasks have been studied for many years and we know the tactics people use, we know far less about searchers’ tactics for how-to technical tasks that involve actually being able to apply found information to resolve a problem. Crucial to our study was developing and studying a highly realistic, how-to technical task, for which there was no single guidance resource: making a phone safe for a child. After providing 39 participants with an actual phone to fix, and a search engine to perform the task, we analysed their search tactics using retrospective cued think aloud interviews. Our primary contribution is a set of 77 tactics used, in three categories, along with detail of how common they were. We conclude that people had a lot of tactics in their repertoire. Although it was not hard for participants to find relevant information, what was hard was for participants to find information they could use; indeed only 23% of participants successfully completed the entire task. Domain knowledge affected the choice of tactics used (although not necessarily towards better task success). We discuss these influences and make design recommendations for how future search systems can support those in resolving how-to technical tasks.     

The effects of mid-flight whole-body and trunk rotation on landing mechanics: implications for anterior cruciate ligament injuries

ABSTRACT

The purpose was to quantify the effects of mid-flight whole-body and trunk rotation on knee mechanics in a double-leg landing. Eighteen male and 20 female participants completed a jump-landing-jump task in five conditions: no rotation, testing leg ipsilateral or contralateral (WBRC) to the whole-body rotation direction, and testing leg ipsilateral (TRI) or contralateral to the trunk rotation direction. The WBRC and TRI conditions demonstrated decreased knee flexion and increased knee abduction angles at initial contact (2.6 > Cohen’s dz > 0.3) and increased peak vertical ground reaction forces and knee adduction moments during the 100 ms after landing (1.7 > Cohen’s dz > 0.3). The TRI condition also showed the greatest knee internal rotation angles at initial contact and peak knee abduction and internal rotation angles and peak knee extension moments during the 100 ms after landing (2.0 > Cohen’s dz > 0.5). Whole-body rotation increased contralateral knee loading because of its primary role in decelerating medial-lateral velocities. Trunk rotation resulted in the greatest knee loading for the ipsilateral knee due to weight shifting and mechanical coupling between the trunk and lower extremities. These findings may help understand altered trunk motion in anterior cruciate ligament injuries.     

Perspectives on peer-review: eight years of Aropä

Drawing on eight years of observation and correspondence from the Aropä project, we report on the issues important to academics who conduct on-line student peer-review activities, and the features they request to support their own instructional designs. The Aropä project is unusually broad, having so far supported over 100 instructors at 20 institutions across nine countries, almost one thousand activities, and more than 36,000 individual students. As the designers, developers, maintainers and advisors of an evolving and widely used tool, we use our unique position to report on the perspectives and priorities of instructors and students in this important and developing field.