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直升机拥有许多其他飞行器所没有的优点,诸如超低空、超低数、前后左右飞行等。其超强的运载与短距离快速机动能力备受军方的青睐。但是正是由于其超低空能力导致了直升机经常出没于人类生存的空间,这就给直升机带来了诸如触碰到高压线、树木、房屋等障碍物的危险,因此而引发的惨剧也经常见诸报端。新型的直升机防撞系统的研制已经势在必行了。 相似文献
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传动系统动力学设计技术是影响直升机飞行安全的关键技术。传动系统装机后的动力特性与旋翼系统、发动机所组成的机械扭转系统耦合特性密切相关,应避免旋翼系统与旋翼轴联接后的振动特性的改变影响其工作性能。动力传动轴和尾传动轴是易频发振动故障的关键部位,应综合考虑各种因素进行分析;应避免主、中、尾减速器装机后频率发生变化与系统模态频率重合,通过有效的隔振系统隔开旋翼通过减速器传递到机身、发动机的振动;舰载直升机着舰时工况恶劣,对传动系统的振动影响也不可忽略。 相似文献
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直升机噪声预测是直升机噪声研究的主要目标之一。文章根据谐波法发展了一种能预测直升机飞越噪声的计算模型。将旋翼自由尾迹分析法所得到的旋翼和尾桨的气动载荷数据代入该模型中,分别计算直升机在悬停和前飞时的有效感觉噪声级,并对其计算结果进行分析。 相似文献
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直升机机械系统的状态直接影响到直升机运行的安全性和可靠性,需要进行周期性的预防性维修以保障直升机能够正常作业,避免发生故障导致人力和物力的损失。本文通过分析直升机机械系统的主要指标,综合考虑直升机实际作业时的不同侧重,建立了直升机机械系统预防性维修周期决策分析模型,以确定多目标情况下的直升机机械系统最优预防性维修周期。 相似文献
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A microfluidic dynamic fluorescence-activated interface control system was developed for lab-on-a-chip applications. The system consists of a straight rectangular microchannel, a fluorescence excitation source, a detection sensor, a signal conversion circuit, and a high-voltage feedback system. Aqueous NaCl as conducting fluid and aqueous glycerol as nonconducting fluid were introduced to flow side by side into the straight rectangular microchannel. Fluorescent dye was added to the aqueous NaCl to work as a signal representing the interface position. Automatic control of the liquid interface was achieved by controlling the electroosmotic effect that exists only in the conducting fluid using a high-voltage feedback system. A LABVIEW program was developed to control the output of high-voltage power supply according the actual interface position, and then the interface position is modified as the output of high-voltage power supply. At last, the interface can be moved to the desired position automatically using this feedback system. The results show that the system presented in this paper can control an arbitrary interface location in real time. The effects of viscosity ratio, flow rates, and polarity of electric field were discussed. This technique can be extended to switch the sample flow and droplets automatically. 相似文献
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为防止驾驶员注意力分散引起无法及时躲避行人造成的事故,利用嵌入式技术、视频跟踪、识别技术,进行行人的快速捕获、识别,建立并形成一个适合于城市交通的嵌入式车载行人检测系统。实验结果表明,本系统可以较为准确地检测行人、提出行车策略及行车建议,有效防止驾驶员误判断现象的出现,提高了行车安全性。 相似文献
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DS18B20是典型的单总线智能温度传感器,由它和单片机AT89C52组成的最小温度检测系统结构简单,功耗低,测温精度高。应用表明,该系统适用于蔬菜大棚中的多温度点检测,能够方便准确地显示蔬菜大棚内的温度,便于控制,能有效保证蔬菜的正常生长。 相似文献
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《Information processing & management》2022,59(2):102867
This paper proposes an algorithm that uses wavelet level adaptive decision-making for detecting high-voltage direct current (HVDC) discharge in wavelet transform cognitively. The identification and detection of HVDC discharge is an essential area of investigation, which contributes to ensuring pipeline safety and the optimal operation of an electrical power system. The proposed algorithm overcomes the wavelet packet transform’s disadvantage of needing to determine the level in advance. The decomposition level of wavelet packet transform is controlled by calculating relative wavelet energy change to decide its wavelet level. Our proposal extracts richer features of HVDC discharge by comparing other feature extraction algorithms. To select the best-suited mother wavelet function, we also design a selection method based on quantitative and qualitative approaches. An additional objective of this study is to detect the phenomenon of HVDC discharge using CP time-series data to assess the corrosion of energy pipelines. Moreover, a third primary discovery is that a wavelet-based application framework is designed to detect the HVDC discharge and further protect the energy pipeline. These discoveries can be valuably applied to the protection of power systems. They also provide brighter perspectives on future opportunities to expand on studies-to-date on the detection and classification of time-series data. 相似文献
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This paper deals with the robust position control problem for a three degree-of-freedom (3DOF) laboratory helicopter. The 3DOF helicopter system is a nonlinear multiple-input multiple-output (MIMO) uncertain system, and has the elevation, pitch, and travel angles. The proposed robust controller is a hierarchical controller including an attitude controller and a position controller. The position controller generates the desired reference of the pitch angle based on the tracking error of the travel angle, while the attitude controller achieves the reference tracking of the pitch and elevation angles. It is proven that the tracking errors of the three angles can converge into the given neighborhoods ultimately. Experimental results on the laboratory helicopter demonstrate the effectiveness of the proposed hierarchical control strategy. 相似文献
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红外热成像技术是一种非接触无损检测的故障诊断技术,它能及时发现和诊断运行电力设备的事故隐患和故障先兆,减少了设备的强迫停运次数,为电力系统的安全稳定运行提供了有力保障。本文通过介绍红外热成像技术在二滩水电站的成功应用案例,分析红外红外热成像测试的影响因素及该技术在应用过程中发现的一些问题及解决方法,为此项技术在其他大型电站电气设备的运行维护工作中的推广和应用提供参考。 相似文献
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油田电力线路运行部门最难处理的故障是解决线路跳闸问题。本文针对如何准确、快速地找到线路故障点进行了探讨,总结出了一些实用有效的输电线路故障查找对策,对提高输电线路故障查找的成功率起到了积极作用。 相似文献