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31.
《Ergonomics》2012,55(3):318-323
Carrying heavy and moderate military loads in backpacks or as body armour compresses the chest, causing a change in lung function that is typical of a restrictive ventilatory impairment. It is not known if a lighter backpack load of only 6?kg, such as is typical of loads carried by students, will have a similar effect on lung function. There have been no studies examining whether backpacks of different strapping styles have an effect on lung function. Several designs of student backpack have recently been introduced to the market. One of the most popular is a single-strap backpack. This study examined Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), FEV1.FVC???1% and Peak Expiratory Flow (PEF) in 13 participants (4 males, 9 females) wearing each of two 6?kg backpacks, one with two shoulder straps (a Double Strap Backpack (DSB)) and the other with a single strap (a Single Strap Backpack (SSB)) worn across the shoulder and chest. In comparison with the control of no pack (N), SSB significantly reduced FVC (by 3.94%, p?=?0.006) but there were no significant differences in FEV1, FEV1. FVC???1% and PEF. The DSB also significantly reduced FVC (by 1.97%, p?=?0.034) but no significant differences were found in FEV1, FEV1. FVC???1% and PEF measures. In comparison with DSB, the SSB was associated with a significantly lower FVC (by 2.05%, p?=?0.049) and FEV1 (by 1.88%, p?=?0.029) but there were no significant changes in FEV1. FVC???1% and PEF. It is concluded that a backpack load of 6?kg could produce a mild restrictive type of ventilatory impairment in lung function. This effect was greater for a single cross-chest strap than for a more conventional double strap harness. 相似文献
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High Broad‐Band Photoresponsivity of Mechanically Formed InSe–Graphene van der Waals Heterostructures 下载免费PDF全文
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Mark Burry 《Architectural Design》2016,86(2):30-35
As Senior Architect to the Basilica of the Sagrada Família in Barcelona, Mark Burry has been ‘thinking parametrically’ for almost his entire career. Here he describes how his longstanding role overseeing the completion of Antoni Gaudí's masterpiece has afforded unique insights into the work of a great geometer and parametric thinker. Burry places the contribution of Gaudí alongside that of Frei Otto – the other eminent 20th-century Proto-Parametricist. 相似文献
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Elena Manferdini 《Architectural Design》2015,85(6):32-39
What happens when you subvert the standardised repetition of the Modernist grid? In Building the Picture, a series of drawings that architect Elena Manferdini produced for an exhibition at the Art Institute of Chicago that ran during the spring and summer of 2015, visual effects and colour were applied to counteract Mies's highly uniform and modular mass-producible systems. 相似文献
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Robert Bevan 《Architectural Design》2015,85(3):16-25
Author and architecture critic for the London Evening Standard, Robert Bevan reflects on the enduring appeal of the temporary structure, speaking ‘to a latent desire for freedom and movement’ as a hangover of our nomadic past in a sedentary ‘civilised’ society. He highlights the type's historical apex in Henry VIII's palatial pop-up on the Field of the Cloth of Gold, questioning the purpose and purposelessness of more recent examples. 相似文献
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利用SolidWorks软件建立了JKM8330高精度随动数控凸轮轴磨床砂轮架的三维模型,导入ABAQUS有限元分析软件,采用弹簧阻尼单元模拟轴承弹性支承的方法,建立了砂轮架的动力学分析有限元模型。通过分析计算,获得了砂轮架的前9阶振型和模态频率,并深入研究了不同轴承弹性支承刚度对砂轮架模态频率的影响规律。结果表明:可以通过调整轴承弹性支承刚度较好地控制砂轮架的模态频率,进而可以减小砂轮架的振动,从而保证机床磨削加工精度及可靠性。研究结果为高精度随动数控凸轮轴磨床的结构优化设计提供了参考。 相似文献
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赖景和 《湖南工业职业技术学院学报》2007,7(2):13-14,17
本文根据CK7815数控车床的刀架系统的故障情况,从分析控制原理入手,利用原机床不用的尾架液压系统对刀架进行改造,有效地提高了刀架定位可靠度和精度,提高了工作效率。 相似文献