Adaptive function projective synchronization of uncertain complex dynamical networks with disturbance

We investigate the problem of function projective synchronization (FPS) in drive-response dynamical networks with non-identical nodes. An adaptive controller is proposed for the FPS of complex dynamical networks with uncertain parameters and disturbance. Not only are the unknown parameters of the networks estimated by the adaptive laws obtained from the Lyapunov stability theory and Taylor expansions, but the unknown bounded disturbances are also simultaneously conquered by the proposed control. Finally, a numerical simulation is provided to illustrate the feasibility and effectiveness of the obtained result.     

In-situ growth of hybrid NaTi8O13/NaTiO2 nanoribbons on layered MXene Ti3C2 as a competitive anode for high-performance sodium-ion batteries

In the work, we successfully explore a two-step hydrothermal method for scalable synthesis of the hybrid sodium titanate (NaTi₈O₁₃/NaTiO₂) nanoribbons well in-situ formed on the multi-layered MXene Ti₃C₂ (designed as NTO/Ti₃C₂). Benefiting from the inherent structural and componential superiorities, the resulted NTO/Ti₃C₂ composite exhibits long-duration cycling stability and superior rate behaviors when evaluated as a hybrid anode for advanced SIBs, which delivers a reversible and stable capacity of ∼82 mAh/g even after 1900 cycles at 2000 mA/g for SIBs.     

Quantification of water and plasma diagnosis for electrothermal vaporization–inductively coupled plasma–mass spectrometry: the use of argon and argide polyatomics as probing species

The water content of the carrier flow originating from an electrothermal vaporization unit (ETV) attached to an inductively coupled plasma mass spectrometer was monitored by following the argon hydride ion (ArH⁺) at m/z=37. The goal was to measure the water expelled by the ETV at sample vaporization and evaluate the influence of this parameter on the ion-generation efficiency. Linear responses from the argon hydride were obtained when the water loading in the plasma injector flow was increased from 0 to 3.3 mg/min. Other argides and water-derived species (Ar⁺, Ar⁺₂ and O⁺₂) were also monitored simultaneously and the effects from operating parameters have been calculated for each species. The magnitude of these effects can eventually be used as diagnosis tools. It was also found that signals for zinc, copper, lead, antimony and arsenic were greatly influenced by slight variations in water loading at low water levels. These signal fluctuations are greatly attenuated and transients' shapes restored by convoluting each element transient with the ArH⁺ or Ar⁺₂ curves that were recorded simultaneously. Envisioned applications that would benefit from a water-enhanced signal include spray electrothermal vaporization, direct sample insertion and laser ablation for inductively coupled plasma–mass spectrometry. The argon dimer Ar⁺₂ seems more appropriate for making the correction since it provides a direct insight on the plasma temperature and provides a robust signal.     

拖曳线列阵声呐平台噪声的空域矩阵滤波抑制技术

针对拖曳线列阵声呐平台噪声构成近场强干扰影响声呐弱目标探测的问题,利用近场平台噪声的多途传播特性,将匹配场定位技术和平面波目标方位估计技术结合,使用平台噪声到达接收阵的拷贝向量以及平面波方向向量共同设计平台噪声零响应约束空域矩阵滤波器,实现了平台噪声抑制.推导得出滤波器设计最优化问题的最优解,利用广义奇异值分解简化最优解表达式,并给出滤波器对平面波方向向量整体响应误差以及对平台噪声拷贝向量响应。利用平台噪声拷贝向量与远场平面波方向向量相关性,解释了平台噪声构成强干扰的原因,以及滤波后存在探测盲区的原因。由仿真可知,空域矩阵滤波处理可获得更小的探测盲区,同时获得盲区外更高的探测能力.      

LBM伪势MRT三维模型GPU并行计算的性能优化

格子Boltzmann方法伪势模型算法中的格点间计算未完全局部化,因此在并行计算时需要更多次的全局内存读写、使用更多数量的寄存器和线程同步操作,从而导致GPU并行计算效率下降.本文针对伪势模型并行计算的局限性,基于三维十五速格子结构的多松弛时间伪势模型,以气液相分离为算例,通过合并访问的方式提高全局内存的读写效率;并提出一种"定向转移"算法,提高格子边界格点获取邻居格点数据的效率;最后探索不同资源分配中各种因素对计算效率的影响,总结最优资源分配的方法.     

纳米流体辐射特性理论分析与实验研究

随着人类社会的飞速发展,能源紧缺、环境污染问题日益严重。当下,开发新能源、发展新能源技术已成为全球各国首要能源策略。作为一种清洁能源,太阳能蕴藏着巨大能量,太阳能利用和相关技术在世界范围内也引起了广泛关注。基于纳米流体的太阳能直接吸收式集热装置能够耦合光伏与光热技术,有利于提高太阳能综合利用的效率。由于纳米流体辐射理论对于开发新的光伏热实验平台具有重要的作用,而纳米流体辐射特性研究仍处于起步阶段,所以对于纳米流体辐射规律及机理的研究具有重要的意义。首先综述了纳米流体辐射特性的研究现状,并对纳米流体的辐射特性进行了理论研究,进而采用瑞利散射模型和Mie(米氏)模型对纳米流体最重要的辐射特性之一的透射率进行了理论分析;而后运用实验进行对比验证,分析不同理论模型与实验数据间的吻合性。结果表明：Mie模型比瑞利散射模型更加准确,在光伏热实验平台开发利用中具有更好的适用性。该研究旨在利用纳米颗粒改变流体对太阳能的辐射特性,探索一种实际设计时纳米流体辐射特性简易高效的计算准则,并得到影响纳米流体辐射特性的重要因素之一的体积分数的变化规律,从而提高太阳能直接吸收式集热装置的太阳能利用率。纳米流体辐射特性理论的分析与研究,有利于促进纳米技术在太阳能领域的应用,提高太阳能的综合利用效率。     

Characterizing the creep of viscoelastic materials by fractal derivative models

In this paper, we make the first attempt to apply the fractal derivative to modeling viscoelastic behavior. The methodology of scaling transformation is utilized to obtain the creep modulus and relaxation compliance for the proposed fractal Maxwell and Kelvin models. Comparing with the fractional derivatives reported in the literature, the fractal derivative as a local operator has lower calculation costs and memory storage requirements. Moreover, numerical results show that the proposed fractal models require fewer parameters, have simpler mathematical expression and result in higher accuracy than the classical integer-order derivative models. Results further confirm that the proposed fractal models can characterize the creep behavior of viscoelastic materials.     

Robust adaptive sliding mode control of MEMS gyroscope using T–S fuzzy model

In this paper, a multi-input multi-output Takagi–Sugeno (T–S) fuzzy model is proposed to represent the nonlinear model of micro-electro mechanical systems (MEMS) gyroscope and improve the tracking and compensation performance. A robust adaptive sliding mode control with on-line identification for the upper bounds of external disturbances and an adaptive estimator for the model uncertainty parameters are proposed in the Lyapunov framework. The adaptive algorithm of model uncertainty parameters could compensate the error between the optimal T–S model and the designed T–S model, and decrease the chattering of the sliding surface. Based on Lyapunov methods, these adaptive laws can guarantee that the system is asymptotically stable. For the purpose of comparison, the designed controller is also implemented on the nonlinear model of MEMS gyroscope. Numerical simulations are investigated to verify the effectiveness of the proposed control scheme on the T–S model and the nonlinear model.     

声矢量传感器线阵波导不变量被动测距研究

介绍一种利用水声信道的统计不变特征(波导不变量)实现被动测距的方法。对接收LOFAR(Low FrequencyAnalysis Record)图使用HOUGH变换等边缘提取技术提取条纹,得到波导不变量以及抛物线参数的估计值,进而得到目标的CPA(Closest Point of Approach)点距离。矢量水听器的振速通道数据所得LOFAR图信噪比明显高于声压LOFAR图,可以提高测距精度。仿真和试验数据结果显示本方法能以较高的精度提取CPA点距离。对比波导不变量经验值和在线估计值所得最近点距离结果,发现使用具有一定精度的在线估计波导不变量值可以显著提高测距精度。