Scheme for antenna design used in in-band full-duplex communication

In order to effectively suppress the self-interference of the in-band full-duplex communication system, a solution for designing the transceiver antenna based on the simple ring structure and collinear dipole is proposed. In this design, two printed dipole antennas are placed in the zero radiation direction of each other to achieve low port isolation between the two transceiver antennas. Then a simple ring structure is added to improve the isolation between the two antennas. Experimental results show that the two transceiver antennas designed by this scheme have omnidirectional radiation characteristics and can obtain a high port isolation of better than 45.9 dB in 2.4~2.6 GHz band. The scheme for designing the transceiver antenna proposed in this paper can not only effectively reduce the interference between two transceiver antennas, but also provide omnidirectional signal coverage. It is an effective solution for designing transceiver antennas for the in-band full-duplex communication system.     

腐蚀凹坑干涉效应与疲劳寿命计算

为了寻求由于腐蚀凹坑尺寸差异引起的干涉效应对凹坑周围应力的影响和预测腐蚀疲劳寿命,采用ANSYS分析和计算不同中心距和深度的腐蚀凹坑在内压作用下的应力分布规律及其疲劳寿命。结果表明：最大应力值随着凹坑深度而增加,但疲劳循环次数却下降,当凹坑深度与器壁厚度大于1/3时其最大应力增长幅度较大;当两凹坑在相切且凹坑深度大于4 mm时干涉效应最显著,应力集中现象更为严重,其疲劳循环次数急剧减少;当相邻两凹坑不相交时干涉效应不明显,相邻两凹坑的最大应力分布及疲劳循环次数均与单凹坑时相近,即两凹坑之间几乎无影响。     

多用户无线供电通信网络中基于最大加权和速率的优化方案

针对多用户无线供电通信网络系统中的交叉耦合干扰问题,提出了一种基于时间反演技术联合优化上、下行时间分配和功率分配方案,以最大化上行加权和速率.利用时间反演特有的空时聚焦性抑制交叉耦合干扰;然后建立优化模型,将难以求解的加权和速率问题转化为最小均方误差问题;最后通过分级逐次优化变量,分别求出功率和时间的最优解.仿真结果表明,在引入时间反演技术抑制系统的交叉耦合干扰后,系统的平均加权和速率明显提升.     

基于EMD时频分析方法的性能研究

针对传统的时频分析方法存在的局限性,评述了一种最新的可适用于非平稳、非线性信号的时频分析法-Hilbert-Huang时频分析.研究了经验模态分解(Empirical Mode Decomposition,EMD)与希尔伯特变换(Hilbert Transformation,HT)相结合的提取信号瞬时特征的EMD/HS法,并对其性能进行了分析.仿真实验中通过与传统的时频分析效果的比较,表明该法具有理想的时频聚集性,并且消除了交叉干扰项.     

基于自适应陷波器的噪声调频干扰抑制方法

针对线性调频引信抗噪声干扰能力比较差的问题,提出了基于自适应陷波器的噪声调频干扰抑制方法。该方法根据线性调频引信差频信号的单频特性,将自适应陷波器应用到线性调频引信中,对噪声调频干扰进行抑制。通过自适应调整陷波器的权值,使陷波器在差频信号的频率点具有陷波特性,从而达到噪声调频干扰抑制的目的。仿真结果表明：SJB=-10 dB时,仍然能达到很好的噪声调频干扰抑制效果。     

复杂电磁环境下电台频率规划和布阵

针对在复杂电磁环境下较小区域内装备之间的干扰问题,对电台频率规划和布阵进行研究。在分析接收机4种干扰的基础上,研究如何在复杂电磁环境下合理进行选频,并利用遗传算法对同频同时工作的电台在较小区域内的优化布阵进行分析,利用matlab软件仿真计算出了7部电台较为合理的布阵方案。结果表明,该方案能在一定程度上降低电台间的干扰,可为在较小区域内布阵电台提供参考。     

Multiwalled carbon nanotubes–BaTiO3/silica composites with high complex permittivity and improved electromagnetic interference shielding at elevated temperature

Composites with silica matrix and mixed filler of multiwalled carbon nanotubes (MWCNTs) and BaTiO₃ powder were fabricated. Excellent uniform dispersion of MWCNTs can be obtained using a two-step mixing method. Both of the real and imaginary parts of complex permittivity increased with increasing MWCNT content and measured temperature. The electromagnetic interference (EMI) shielding results showed that the absorption mechanism is the main contribution to the total EMI shielding effectiveness (SE). Compared with the EMI SE resulting from reflection, the absorption showed more dependence on the MWCNT content, measured temperature and frequency. The total EMI SE is greater than 20 dB at 25 °C and 50 dB at 600 °C in the whole frequency range of 12.4–18 GHz with a 1.5 mm composite thickness, which suggests that the MWCNT–BaTiO₃/silica composites could be good candidates for the EMI shielding materials in the measured frequency and temperature region.     

Drying dynamics of polymers films by an interferometric technique

We analyze a simple laser reflectivity measurement as a tool to monitor the drying kinetics of transparent polymer films. The reflectivity signal of a laser beam at normal incidence shows oscillations due to interference arising from multiple reflection of the laser light within the drying film. We develop a model to interpret the reflectivity curves in terms of time evolving refractive indices at the top and bottom of the film. We present results of the drying kinetics of transparent alkyd films on a glass substrate of high refractive index. Data shows a clear hallmark indicating the evolution of the crosslinking process. From the reflectivity curves, the time evolution of the refractive indices at the top and bottom is obtained. Assuming a linear-gradient of the refractive index along the depth of the film the average refractive index and consequently the film thickness as a function of time are estimated. Clear features in the time evolution of the refractive indices and thickness, correlate well with qualitative “dust”, “touch” and “fingerprint” drying times. Additionally, we present some preliminary results for water based latex binders, where scattering of light is present, showing that this simple optical technique could be extended for studying latex film formation.     

渤海Q油田层间干扰定量表征技术及应用

针对渤海Q油田北区块油井多层合采导致的含水上升快、采油速度低、采出程度差异大等问题,对不同含水阶段的层间干扰现象进行分析,建立了层间干扰定量表征技术,并结合Q油田油藏类型和储层纵向非均质性,研究了底水关闭前后不同含水阶段的层间干扰规律,提出了高含水期细分层系开发的技术对策:对北区块进行调整,将原来的一套开发层系细分为三套开发层系,采用水平井开发,同时对老井进行关层。调整后全区含水率下降了10%,采油速度提高了0.5%,采收率提高了10.6%。     

低应变瞬态荷载作用下基桩动力响应解析解

目前广泛采用的基桩低应变检测问题的理论基础是基于平截面假定的一维应力波理论。而实际上,锤击产生的应力波是三维应力波,不仅沿桩身纵向传播,还沿径向传播,对于基桩低应变检测问题平截面假定实际上是不成立的。此时,一维纵波传播问题转换为应力波沿三维柱体传播问题。文章从基桩三维理论出发,忽略桩土径向位移,考虑桩体中应力波沿纵向和径向传播与桩土的相互作用,建立三维条件下桩土系统瞬态振动计算模型,推导得到低应变瞬态荷载作用下基桩三维动力响应的解析解,以期为基桩低应变检测提供新的理论指导。