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71.
以某行星齿轮传动为研究对象,分析行星齿轮传动原理;建立行星齿轮三维模型,导入仿真软件Romax对行星齿轮传动模态、固定内齿圈振动加速度、振动速度等振动特性进行仿真分析。仿真结果表明:行星齿轮传动不同阶数下的振动频率、振型和振动总位移不同;行星齿轮传动固定内齿圈的振动加速度、振动速度都呈现在某一均值波动的情况。该研究为避免行星齿轮传动发生共振、减小振动噪声及增加疲劳寿命提供理论依据。 相似文献
72.
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74.
《International Journal of Hydrogen Energy》2019,44(10):4698-4706
Polyaniline is a typical conducting polymer with high migration electron rate, good stability, eco-friendly properties, and high absorption coefficients for visible light. In the present study, polyaniline decorated Pt@TiO2 for visible light-driven H2 generation is reported for the first time. The above-mentioned nanocomposite is prepared through a simple oxidative-polymerization and characterized by infrared spectroscopy, transmission electron microscopy, X–ray diffraction, thermogravimetric analysis, and ultraviolet–visible diffuse reflectance spectra. Polyaniline modification improves the absorption of the nanocomposite in visible light region via a photosensitization effect similar to dye–sensitization but does not influence the crystal structure and size of Pt@TiO2. The polyaniline modified Pt@TiO2 exhibits a remarkable visible light activity (61.8 μmol h−1 g−1) and good stability for H2 generation (with an average apparent quantum yield of 10.1%) with thioglycolic acid as an electron donor. This work provides new insights into using conducting polymers, including polyaniline, as a sensitizer to modify Pt@TiO2 for visible-light hydrogen generation. 相似文献
75.
《International Journal of Hydrogen Energy》2022,47(36):16132-16143
In our earlier study, it has been shown that trace Na additions can improve the reaction kinetics of Mg–5%La (wt.%) alloys during the first absorption. However, the subsequent hydrogen desorption/absorption process of the Mg–5%La after the first absorption has not been investigated. In this study, we have investigated the hydrogen sorption behaviour of the Mg–5%La alloy after the first absorption in terms of phase evolution, and lattice expansion properties during desorption as function of temperature using in-situ synchrotron Powder X-ray Diffraction (PXRD) and in-situ High Voltage Transmission Electron Microscopy (HVTEM). Two distinct phase evolutions, a continuous phase transformation of LaH3 → LaH2 + ½ H2 (from 250 °C) and decomposition of MgH2 → Mg + H2 (between 440 and 460 °C) were identified during the desorption. It is determined that this alloy is cyclable in the absence of Mg12La intermetallic during the subsequent absorption/desorption cycling after the first hydrogen absorption. 相似文献
76.
Seyed Ali Mohajeran Ghosheh Abed Hodtani 《International Journal of Communication Systems》2020,33(14)
In this paper, the power allocation problem in a wireless sensor network (WSN) with binary distributed detection is considered. It is assumed that the sensors independently transmit their local decisions to a fusion center (FC) through a slow fading orthogonal multiple access channel (OMAC), where, in every channel, the interferences from other devices are considered as correlated noises. In this channel, the associated power allocation optimization problem with equal power constraint is established between statistical distributions under different hypotheses by using the Jeffrey divergence (J‐divergence) as a performance criterion. It is shown that this criterion for the power allocation problem is more efficient compared to other criteria such as mean square error (MSE). Moreover, several numerical simulations and examples are presented to illustrate the effectiveness of the proposed approach. 相似文献
77.
Yudi ZHANG Debiao HE Mingwu ZHANG Kim-Kwang Raymond CHOO 《Frontiers of Computer Science》2020,14(3):143803-215
Mobile devices are widely used for data access,communications and storage.However,storing a private key for signature and other cryptographic usage on a single mobile device can be challenging,due to its computational limitations.Thus,a number of(t,n)threshold secret sharing schemes designed to minimize private key from leakage have been proposed in the literature.However,existing schemes generally suffer from key reconstruction attack.In this paper,we propose an efficient and secure two-party distributed signing protocol for the SM2 signature algorithm.The latter has been mandated by the Chinese government for all electronic commerce applications.The proposed protocol separates the private key to storage on two devices and can generate a valid signature without the need to reconstruct the entire private key.We prove that our protocol is secure under nonstandard assumption.Then,we implement our protocol using MIRACL Cryptographic SDK to demonstrate that the protocol can be deployed in practice to prevent key disclosure. 相似文献
78.
在流程工业生产中,移动物料计量信息的传输普遍采用电台和无线模块。接收电台周围环境严重影响计量信息的传输效果,尤其是钢结构厂房、电磁干扰区内,数据传输过程中的丢包率、误码率相当严重。本文提出一种多节点分布式传输方法,根据各个生产作业区环境条件设置相应的WIFI节点数,实现对作业区的无线信号覆盖。网络覆盖区内无线模块、PDA终端(PDA)、终端查询设备通过节点工作频段和阵列天线自适应调节,实现数据传输最佳化。铜熔炼生产现场测试表明,此种传输方法可以有效消除周围环境的电磁干扰,数据丢包率低于0.1%。 相似文献
79.
随着物联网(IoT)的快速发展,越来越多的IoT节点设备被部署,但伴随而来的安全问题也不可忽视。IoT的网络层节点设备主要通过无线传感网进行通信,其相较于互联网更开放也更容易受到拒绝服务等网络攻击。针对无线传感网面临的网络层安全问题,提出了一种基于序列模型的网络入侵检测系统,对网络层入侵进行检测和报警,具有较高的识别率以及较低的误报率。另外,针对无线传感网节点设备面临的节点主机设备的安全问题,在考虑节点开销的基础上,提出了一种基于简单序列模型的主机入侵检测系统。实验结果表明,针对无线传感网的网络层以及主机层的两个入侵检测系统的准确率都达到了99%以上,误报率在1%左右,达到了工业需求,这两个系统可以全面有效地保护无线传感网安全。 相似文献
80.
随着汽车及机床行业的发展,板料涂油工艺在汽车零部件生产中应用广泛,从而导致板料在自动切割生产过程中极易打滑跑偏,无法保证传输精度,本文所阐述的磁性辊轮驱动装置从根本上有效解决了此问题,在切割生产线中有广泛的推广价值。 相似文献