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101.
102.
In this paper, a compact asymmetric coplanar waveguide (CPW) feed with split-ring resonator (SRR) is proposed to resonate at dual-band operations for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The asymmetric CPW-fed SRR patch (ACSP) antenna consists of a meander line, square-shaped split ring, and CPW ground plane. The proposed ACSP antenna resonates at two operating frequencies, namely, 2.48 GHz (2.4–2.74 GHz) and 3.49 GHz (3.25–3.64 GHz) with reflection coefficients (S11) of −16.65 dB and −32.67 dB, respectively. The measured results agree closely with the simulation results of the proposed antenna. 相似文献
103.
众所周知,矿物质的成分是多种多样的,社会的发展和科学的进步需要运用到多重金属矿物质,在专业人员的勘探与挖掘中,发现了黄沙坪铅锌多金属矿,这个矿区中有丰富的有色金属,这个矿的发掘为研究成矿规律提供了物质基础,同时也为深部找矿提供了可靠的依据。本文主要分析黄沙坪铅锌多金属矿的成矿规律及深部找矿远景。 相似文献
104.
为了使7075铝合金薄壁件表面喷丸加工应力得到松弛和均化,运用ANSYS建立平台式振动时效有限元模型,通过振动模态和谐响应分析,获得最佳激振频率和试样装夹位置。在此基础上,将薄壁框架件置于平台上进行振动时效处理,以验证仿真分析结果,评价其对试样表面应力作用效果。结果表明:在亚共振频率为112 Hz时,试样在平台零振幅和最大弯曲位置处分别对称布置,时效后表面均形成应力松弛,松弛率分别为29.5%和33.3%,不均匀波动分别为20.3%和20.7%,而沿振动方向松弛程度不均匀,说明激振力造成了材料表面组织屈服,且屈服程度与应力强度有关。提出再时效-位置交叠方法,使应力松弛不均匀度分别下降到9.9%和15.9%,应力均化得到改善,该研究工作为薄壁类零件表面应力均匀化提供了参考。 相似文献
105.
《全球能源互联网(英文)》2020,3(4):313-323
Recently, power electronic transformers (PETs) have received widespread attention owing to their flexible networking, diverse operating modes, and abundant control objects. In this study, we established a steady-state model of PETs and applied it to the power flow calculation of AC–DC hybrid systems with PETs, considering the topology, power balance, loss, and control characteristics of multi-port PETs. To address new problems caused by the introduction of the PET port and control equations to the power flow calculation, this study proposes an iterative method of AC–DC mixed power flow decoupling based on step optimization, which can achieve AC–DC decoupling and effectively improve convergence. The results show that the proposed algorithm improves the iterative method and overcomes the overcorrection and initial value sensitivity problems of conventional iterative algorithms. 相似文献
106.
随着风能资源的广泛应用,机组组合问题求解愈显复杂。以减少煤耗费用提高系统经济性为目标,提出一种采用遗传萤火虫算法求解含风电电力系统机组组合问题的新方法。引入遗传算法双矩阵通路判断及约束修复策略,提高了初始解生成质量及产生速度;再利用萤火虫算法求解连续负荷经济优化分配,给出自适应交叉概率,从而提高了算法的收敛速度。应用所提算法对经典10机系统优化仿真表明,与其他算法相比,该方法能合理安排机组组合,提高系统供电的经济性,具有较好的实用价值。 相似文献
107.
In this paper, a triple shape memory material was prepared by ultra‐simple melt blending from poly(ε‐caprolactone) (PCL), poly(propylene carbonate) (PPC) and ethylene‐α‐octene block copolymer (OBC). The obtained material possessed a co‐continuous phase morphology and presented an excellent triple shape memory effect (triple‐SME). Theoretical prediction demonstrated that a special continuous phase morphology could be constructed by adjusting the proportions of the blend. Moreover, the results indicated that a close relationship existed between the phase morphology and the triple‐SME of PCL/PPC/OBC. The sample with 35 vol% PPC content contributed to the formation of a continuous phase morphology and exhibited the optimal triple‐SME. Additionally, the sample PCL/PPC/OBC (32.5/35/32.5) showed outstanding structure and performance stability during cycle loading–unloading tests, which evidenced the prominent cycling shape memory property (nearly 100% shape fixing and recovery of temporary shape). Overall, this work could provide an efficient, convenient and recyclable method to obtain high‐performance shape memory materials. © 2020 Society of Chemical Industry 相似文献
108.
《Digital Communications & Networks》2020,6(2):229-237
With the rapid development and widespread application of Wireless Body Area Networks (WBANs), the traditional centralized system architecture cannot handle the massive data generated by the edge devices. Meanwhile, in order to ensure the security of physiological privacy data and the identity privacy of patients, this paper presents a privacy protection strategy for Mobile Edge Computing(MEC) enhanced WBANs, which leverages the blockchain-based decentralized MEC paradigm to support efficient transmission of privacy information with low latency, high reliability within a high-demand data security scenario. On this basis, the Merkle tree optimization model is designed to authenticate nodes and to verify the source of physiological data. Furthermore, a hybrid signature algorithm is devised to guarantee the node anonymity with unforgeability, data integrity and reduced delay. The security performance analysis and simulation results show that our proposed strategy not only reduces the delay, but also secures the privacy and transmission of sensitive WBANs data. 相似文献
109.
110.