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飞机设计时,对座舱的舒适性有一定要求。根据某背负式单发螺旋桨飞机的研制需要,利用机载振动实时测试系统对飞机座椅处的振动特性进行了飞行测试,并对测试数据进行了带通滤波处理,分析了座舱乘员全身振动暴露的舒适性降低限。结果表明,飞机当前的座椅振动水平至少满足飞行4小时的舒适性要求。分析结果为飞机座舱的舒适性评估提供了依据。 相似文献
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螺旋桨飞机飞行过程中,存在多种振源扰动。根据某螺旋桨飞机振动测试分析的需要,设计了一种机载振动实时测试系统,采用飞行试验进行机体动态响应测试,以评估飞机的颤振、振动特性。系统测试检查结果表明,测试过程中、系统工作正常,测试结果符合实际情况,且测试系统对机上系统无不利影响。对于螺旋桨飞机,机载振动实时测试系统对飞机的颤振、振动评估有重要意义。 相似文献
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电机的故障诊断有电流分析法、振动诊断法、绝缘诊断法、温度诊断法、振声诊断等。在分析了电机其型故障的振动特征后,利用振动诊断法对某煤矿主通风机电动机的故障进行分析和诊断。 相似文献
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电机的故障诊断有电流分析法、振动诊断法、绝缘诊断法、温度诊断法、振声诊断等。在分析了电机其型故障的振动特征后,利用振动诊断法对某煤矿主通风机电动机的故障进行分析和诊断。 相似文献
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针对某型控制板的振动耐久例行试验中出现的连接螺钉脱落和断裂现象,仿真计算正常和松动两种状态的螺钉响应应力,比较分析确定螺钉折断的原因为螺钉松动,并提出了相应的规程要求。 相似文献
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某工程部分节点是多根杆件焊接相连,节点牛腿内翼板与中间板采用全熔透焊缝,节点牛腿的主焊缝采用部分熔透,节点中间劲板与外翼缘板的焊缝及中间劲板与牛腿腹板的焊缝采用部分熔透焊缝,因此在节点部位存在多次焊接,为检测焊接在节点区域产生的残余应力,评价残余应力对结构的影响程度,特进行此次试验。本文采用盲孔法对节点进行了残余应力测试,同时对节点进行了振动"时效"消除残余应力试验研究。研究表明,由于节点焊缝较多,所以产生的残余应力很大;振动"时效"消除残余应力试验结果说明应力消除是有效的。 相似文献
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A rotary variable admittance device and its application in vehicle seat suspension vibration control
Donghong Ning Shuaishuai Sun Jianqiang Yu Minyi Zheng Haiping Du Nong Zhang Weihua Li 《Journal of The Franklin Institute》2019,356(14):7873-7895
In this paper, a novel semi-active variable admittance (VA) concept is proposed, and a seat suspension prototype with a magnetorheological fluid damper based rotary VA device is designed, manufactured, and experimentally validated. The conventional inerter with a single flywheel has a constant inertance, which can effectively improve the suspension performance by being integrated into a mechanical network with springs and dampers. The proposed rotary VA device comprises a gear reducer, two flywheels and a variable damping (VD) device which is used to connect the two flywheels. With carefully designing, the rotary VA device is compacted and is similar with a VD device in size. The rotary VA device is installed in the centre of a seat suspension's scissors structure to form a VA seat suspension. According to the test results, the equivalent inertance of the seat suspension can vary from 11.3 Kg–76.6 Kg with a 3 Hz frequency and 5 mm amplitude sinusoidal movement by changing the current from 0 A–1 A. By analysing the system characteristics, a hybrid controller with two acceleration feedbacks is proposed. Thereafter, the seat suspension and controller are validated in experiments by comparing the performance with a conventional passive seat suspension. The random vibration test shows the excellent performance of the proposed seat suspension; the frequency weighted root mean square acceleration of the seat is reduced by 43.6%, which indicates a great improvement of the ride comfort. The VA device shows great prospect in the suspension application. 相似文献
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The frequent occurrence of security incidents in ride-sharing is a challenge for the survival of IT-enabled ride-sharing platforms. Passengers’ protective behavior is an effective means to alleviate this issue, with benefits to both the passengers and the platforms. This study explores the mechanisms of passengers’ protective behavior in the ride-sharing context by combining protection motivation theory (PMT) and usage situation theory. We test our hypotheses using data (n = 346) collected from a field survey based on a real scenario. The findings reveal that PMT and usage situation theory work well to explain passengers’ protective behavior during ride-sharing. This study explains the motivation behind passengers’ protective behavior in the ride-sharing context, extends the contents of PMT by exploring its antecedents, and extends the contents of usage situation theory by introducing a new dimension. Our findings can help ride-sharing platforms take appropriate strategies to improve passengers’ protective behavior. 相似文献
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This paper explores the barriers and drivers of diffusion associated with permissionless and permissioned blockchains, seeking to establish whether they are the same or different and whether barriers and drivers change over time. The study was undertaken in two stages: (i) interviews in 2016 that examine the barriers and drivers of diffusion; followed by (ii) a case study in 2019 of the Italian wine industry’s permissioned blockchain. The results show that diffusion is reaching a final stage for permissionless blockchains but is lagging behind for permissioned blockchains due to the different barriers and drivers of diffusion.The implications from this study are that: (i) drivers and barriers for different types of technological innovation may be different and change over time; (ii) initial barriers may be surmounted and become features of the underlying technology; (iii) barriers may become drivers of a technology; (iv) drivers of one type of technology may spill-over to become drivers for another type; (v) diffusion may be measured by both the number of adoptions and the number of participants in that technology; (vi) off-chain processes may become a major barrier for permissioned blockchains; and finally (vii) self-interest may be the key driver of technological innovation. 相似文献
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随着IT技术的不断发展,出现了越来越多的新设备,操作系统为了保持对这些新设备以及已有老设备的支持,其内核就要加入越来越多的驱动代码,驱动代码的加入使得原本已经复杂的内核更加庞大,且这些代码可能潜伏着许多漏洞,威胁系统安全。而微内核系统将设备驱动独立于用户空间,不再处于内核中,使得设备驱动不会影响到内核的安全,这种设计对于减少系统安全威胁帮助很大。 相似文献
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NDIS中间层驱动功能强大,是个人防火墙技术的发展趋势。介绍了利用NDIS中间层驱动截获到主机的数据包并进行分析、过滤掉有威胁的数据包的工作流程及程序。 相似文献
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在出租车行业中,“绕路”占据民事纠纷或投诉的最大比例,造成这种情况的原因除了驾驶员职业道德因素外,很大一部分原因在于驾驶员对道路的熟悉程度不够.从基于图像的虚拟现实技术特点入手,分析了将全景虚拟展示方法用于出租车驾驶员熟悉道路培训的可行性和有效性,最后介绍了 Google Maps 全景图与模拟驾驶设备相结合的培训系统的具体实现. 相似文献
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《International Journal of Information Management》2016,36(5):711-723
This paper examines the key drivers of mobile marketing adoption intention by South African SMEs using a multi-perspective framework that combines elements in the technological, organisational and environmental contexts of the enterprises. Data was collected from a random sample of 205 SMEs from Gauteng, South Africa. Structural equation modelling was used to analyse the data. The results identified perceived relative advantage, perceived cost, top management support, employees’ IT capability, and customer pressure as important drivers of mobile marketing adoption intention. Of these factors, top management support emerged as the strongest driver of adoption intention. The implications of these findings for mobile marketers and others interested in accelerating the adoption of mobile marketing among SMEs are highlighted. 相似文献
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介绍了一种以单片机为控制核心的制动力大小警示系统的研究与开发:采用制动油压传感器,以LED数码显示器在车内向驾驶员告知制动油压具体值,检测制动系统是否正常工作;以LED红色警示灯在后窗,向后面行车驾驶员提供制动力参考,使其控制合适车距,避免追尾。 相似文献
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本文论述了高陡路堑爆破开挖中减振技术,通过采用预裂深孔松动控制爆破技术、同段位高段别微差起爆技术,实现了降低爆破震动、控制高程振动放大效应、减轻累积爆破损伤作用,减轻了爆破震动带来的边坡破坏扰动作用,保证了高陡边坡的长期稳定。 相似文献
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对于飞行试验中非平稳振动信号,进行时频分析后仅可定性的观察到频率值随时间发生变化的趋势,为了确定振源机理,需要进一步寻求频率变化与飞行参数变化之间的相关性.提出了一种把所关注频率值的变化曲线从时频分析图中提取出来的方法,以定量的研究引起频率值变化的原因.针对某型机平飞状态出现的垂尾尖部振动较大现象,运用此方法提取频率变化线,通过与发动机参数的对比与拟合,确认了该振动产生的振源来自发动机的高压转子. 相似文献