Is nonlinear model predictive control with fuzzy predictive model proper for managing the blood glucose level in typeI diabetes?

In recent decades, due to the increasing risk of diabetes, the measurement and control of the blood sugar is of great importance. In typeI diabetes, because of the lack of insulin secretion, the cells cannot absorb glucose, and thus have a low level of glucose. To control blood glucose, the insulin must be injected to the body. In fact, the injection must be in a completely controlled environment. If the level of the insulin exceeds the physiological limits, it may cause death. This paper presents an online approach to control the blood glucose level using a nonlinear model predictive control. This method, maintains the level of blood glucose concentration within a normal range. Thus, the blood glucose level is measured in each minute and predicted for the next time interval. If that is not in the normal range, amount of the insulin which must be injected will be determined. The proposed control approach includes important features such as model uncertainties and prevents acute decrease in the blood glucose level, and instability. In order to assess performance of the proposed controller, computer simulations have been carried out in Matlab/Simulink. Simulation results will reveal the effectiveness of the proposed nonlinear model predictive controller in adjusting the blood glucose level by injecting required insulin. So if the nutrition of the person decreases instantly, the hypoglycemia does not happen.

Symplectic multi-level method for solving nonlinear optimal control problem

By converting an optimal control problem for nonlinear systems to a Hamiltonian system,a symplecitc-preserving method is proposed.The state and costate variables are approximated by the Lagrange polynomial.The state variables at two ends of the time interval are taken as independent variables.Based on the dual variable principle,nonlinear optimal control problems are replaced with nonlinear equations.Furthermore,in the implementation of the symplectic algorithm,based on the 2N algorithm,a multilevel method is proposed.When the time grid is refined from low level to high level,the initial state and costate variables of the nonlinear equations can be obtained from the Lagrange interpolation at the low level grid to improve efficiency.Numerical simulations show the precision and the efficiency of the proposed algorithm in this paper.

基于水平集带方法的柔顺机构拓扑优化研究

水平集方法在拓扑优化问题中采用隐式函数的零水平集描述结构边界,由于可以方便的表达结构拓扑变化并使结构边界保持清晰和光滑的特性,水平集方法很快成为拓扑优化领域的重要方法之一。但是由于水平集方法在优化过程中存在拓扑变化的不连续性,容易出现数值不稳定、初始设计依赖性等问题。近年来水平集带方法的提出可以有效改善这一现象,成为提升水平集方法拓扑表达能力的重要手段。本文将水平集带引入到参数化水平集拓扑优化方法中,并对其在柔顺机构优化设计问题中的应用开展研究。水平集带方法在水平集函数的零水平集附近引入水平集带区域,采用水平集函数插值可以得到带宽范围内[0,1]区间连续分布的材料密度,并在优化过程中通过逐渐减小水平集带的宽度使带宽范围内的材料密度逐渐收敛至0-1分布。该方法结合了变密度法的优势,使优化过程中材料密度变化保持连续,可以提升参数化水平集方法的稳定性,得到更优的目标函数值,并有效改善水平集方法的初始设计依赖性问题。本文通过多个柔顺机构的拓扑优化算例从不同初始设计、不规则设计域及几何非线性等多方面分析和验证了该方法的有效性,计算结果表明该方法对面向实际工程的复杂设计问题具有较好的适用性。

电动式换能器:结构、性能及其在声学模拟和校准中的应用与发展趋势

电动式换能器以其小尺寸、超低频、超宽带发射的特点,在舰船辐射噪声模拟、声呐系统校准等领域具有广泛应用。总结了电动式换能器的结构及性能特点,讨论了超低频、超宽带发射的原理,回顾了电动式换能器驱动磁路优化、工作频带拓宽、工作深度提升等相关工作。针对电动式换能器研究中的非线性问题,提出了优化驱动磁路来降低输出力的非线性效应、改善电动式换能器与功率放大器的阻抗匹配以降低波形畸变及谐波失真。对于声腔对换能器性能的影响,可以通过在声腔内充入特性阻抗较小的气体以抑制声源级响应起伏现象。电动式换能器未来的研究应以改善大深度环境下超低频段的声辐射性能、提升连续工作时间及可靠性、降低非线性失真为主要方向。

电子通信突变非线性多频干扰检测方法

电子通信中同频段窄带信号通常含有多种不同频谱的非线性信号,对通信造成突发性干扰。此类非线性信号干扰的多频段表现性强且特征种类多,检测难度较大。为此提出一种考虑动态特征的突变非线性多频干扰检测方法。构建电子通信模型,采集信号样本,根据时域逐步增加的关系完成信号的扩频。计算扩频前和扩频后的幅度差值,根据信号跟随时间变化的递推关系推导出每个源点区域的实时状态特征。采用DFT多级模型按照特征大小顺序逐一检测,若信号超过门限值,则输入到下一级检测层中;若信号低于门限值,直接输出非线性多频干扰检测结果。实验证明:研究方法能够高精度检测电子通信突变非线性多频干扰的时域和频域幅值,说明上述方法的应用性能更好,研究价值较高。

基于扰动观测器的双容液位系统RBF神经网络滑模控制

针对双容液位系统存在的外部扰动、模型参数不确定等问题,设计了一种基于非线性扰动观测器(nonlinear disturbance observer,NDOB)的径向基函数神经网络滑模控制(radial basis function neural network sliding mode control,RNNSMC)方法。建立双容液位系统数学模型,采用积分型滑模面来提高系统的鲁棒性,在常规积分滑模控制的基础上,通过RBF神经网络(RBF neural network,RNN)对系统的非线性函数进行逼近,并设计非线性扰动观测器估计外部扰动,选用Lyapunov稳定性判据证明了控制策略的闭环稳定性。仿真结果表明,所提控制策略与积分滑模控制(integral sliding mode control,ISMC)方法相比,不需要精确的数学模型,且控制精度更高,抗干扰能力更强。

基于客流博弈均衡的旅客列车双层开行方案优化

为提高旅客列车运行效益及旅客出行满意度,以铁路运营部门净收益、列车空座位走行公里最小化为上层0-1规划模型,以旅客出行满意度最大化为下层客流均衡模型,构建了纯整数非线性高速铁路旅客列车开行方案双层规划模型。针对下层客流均衡模型,通过划分博弈环境和分析旅客乘车出行选择行为,选取旅客同质群体作为局中人,构造各局中人合理赢得函数,对每个博弈环境均运用非合作博弈理论进行客流均衡分配。基于构建的模型特征分析,采用NSGA-Ⅱ算法求解上层停站方案模型,运用QPSO算法求解下层客流博弈均衡模型,并以兰新高速铁路为例验证了模型及算法的可行性。结果表明:该算法可获得使铁路运营部门与旅客双方均满意的Nash均衡解,由此得到的开行方案铁路旅客损失率为0%。

电力隧道自动巡检机器人调平系统设计与运动学分析

为了解决机器人在行走过程中车身倾斜导致数据采集失准的问题,设计了一款基于比例-积分(Proportional Integral,PI)鲁棒滑模控制系统的3-RPS并联调平机构。首先,根据螺旋和反螺旋理论进行了构型综合;其次,对3-RPS调平机构进行了动力学分析计算,构建其动力学模型,并在此基础上引入自适应鲁棒滑模算法,对PI控制器进行优化改进,提高稳定性和自适应修正能力,利用李雅普诺夫(Lyapunov)函数对非线性控制系统进行了稳定性验证;最后,通过Matlab/Simulink对比模拟试验,获得控制误差曲线。仿真结果表明,基于鲁棒滑模算法优化后的PI控制系统自适应修正效果显著,大幅度降低了控制稳态误差。研究为3-RPS并联调平机构物理样机研制提供了基础。

Distribution of Vibrational Energy Levels of Protein Molecular Chains

The distributions of the quantum vibrational energy levels of the protein molecular chain are found by the discretely nonlinear Schrodinger equation appropriate to protein obtained from the Davydov theory. The results calculated by this method are basically consistent with the experimental values. Furthermore, the energy spectra at high excited states have also been obtained for the molecular chain which is helpful in researching the properties of infrared absorption and Raman scattering of the protein molecules.

Periodic Modulation of Nonlinearity in a Two-Core Photonic Crystal Fiber: A Numerical Investigation

We present a numerical investigation of the propagation and the switching of ultra-short pulses (100 fs) in a two-core nonlinear coupler of photonic crystal fibers constructed with periodically modulated the non-linearity fiber (PMNL-PFC). Our simulations are taking into account different amplitude and frequency modulations of the PMNL-PFC. A coupler for coupling whose length is Lc = 1.8 cm, the transmission characteristics, the compression factor, the crosstalk (Xtalk) and extinction ratio (Xratio) levels of the first order solitons were studied for low to high pump energies considering 2Lc. By an analysis on the reference channel (channel 2), it is observed that at low modulation frequencies an increase occurs in the switching power increasing transmission efficiency. For high modulation frequencies, the transmitted energy efficiency loses. The switching pulses are stronger for low frequency and high amplitude modulation. The Xtalk is a function of the measurement made on the secondary channel (channel 1). It was observed that this unwanted high-frequency energy increases to lessen the measure of the amplitude modulation. In summary, we have demonstrated that introduction of a non-linearity profile takes the periodically modulated PMNL-PFC to strong variations at transmission efficiency, Xtalk, Xratio a function of frequency and modulation amplitude and the input power.

A new finite difference scheme for a dissipative cubic nonlinear Schrdinger equation

This paper considers the one-dimensional dissipative cubic nonlinear SchrSdinger equation with zero Dirichlet boundary conditions on a bounded domain. The equation is discretized in time by a linear implicit three-level central difference scheme, which has analogous discrete conservation laws of charge and energy. The convergence with two orders and the stability of the scheme are analysed using a priori estimates. Numerical tests show that the three-level scheme is more efficient.

Effects of periodic modulation on the nonlinear Landau-Zener tunneling

We study the Landau-Zener tunneling of a nonlinear two-level system by applying a periodic modulation on its energy bias. We find that the two levels are splitting at the zero points of the zero order Bessel function for high- frequency modulation. Moreover, we obtain the effective coupling constant between two levels at the zero points of the zero order Bessel function by calculating the final tunneling probability at these points. It seems that the effective coupling constant can be regarded as the approximation of the higher order Bessel function at these points. For the low-frequency modulation, we find that the final tunneling probability is a function of the interaction strength. For the weak inter-level coupling case, we find that the final tunneling probability is more disordered as the interaction strength becomes larger.

A study on the seismic behavior of a retrofitted building based on nonlinear static and dynamic analyses

This study describes the seismic performance of an existing five storey reinforced concrete building which represents the typical properties of low-rise non-ductile buildings in Turkey. The effectiveness of shear walls and the steel bracings in retrofitting the building was examined through nonlinear static and dynamic analyses. By using the nonlinear static analysis, retrofitted buildings seismic performances under lateral seismic load were compared with each other. Moreover, the performance points and response levels of the existing and retrofitting cases were determined by way of the capacity-spectrum method described in ATC-40 (1996). For the nonlinear dynamic analysis the records were selected to represent wide ranges of duration and frequency content. Considering the change in the stiffness and the energy dissipation capacities, the performance of the existing and retrofitted buildings were evaluated in terms of story drifts and damage states. It was found that each earthquake record exhibited its own peculiarities, dictated by frequency content, duration, sequence of peaks and their amplitude. The seismic performance of retrofitted buildings resulted in lower displacements and higher energy dissipation capacity depending mainly on the properties of the ground motions and the retrofitting strategies. Moreover, severe structural damage (irreparable or collapse) was observed for the existing building. However, buildings with retrofit alternatives exhibited lower damage levels changing from no damage to irreparable damage states.

Period components in the monthly mean sea level variations in the Pacific Ocean

To study the period components in the monthly mean sea level variations in the Pacific Ocean, this paper analyses the monthly mean series of 236 tide gauge stations in the Pacific on the basis of the improved analytical method of the monthly mean sea level period signals. The results show that the oscillation periods of the sea level series are not fixed, but vary with stations. This paper also discusses the existences of the quasi-2 years atmospheric oscillation period, the 3～7 a period related to the El Nino events, sunspots, double sunspots and the 25～30 a overlength oscillation periods. The corresponding amplitudes and initial phase angles as well as the linear trend coefficient are obtained by using significant period components plus the linear trend to fit the monthly mean sea level series. A conspicuous features of the results are found,i. e.,taking 25°～30°S as the axial line in the Pacific, the annual lags gradually increase to the north and the south respectively, depicting a variation trend of partial symmetry. But in China seas, the north and south distributional trend of the annual period lags is almost opposite to those in most parts of the Pacific Ocean. In the low-latitude zone where El Nino events occur or impose more significant effects, the ratio of the sum of amplitudes of various periods within 2～7 a to the annual amplitude is equal to or more than 1. 0, while that of the sum of amplitudes of periods larger than 8 a to the annual amplitude is equal to or more than 0. 5. This suggests that the dominant role of annual amplitude in the monthly mean sea level series of this region has declined and that, correspondingly, there exist significant period components of El Nino events as well as the long-period oscillations of quasi-10 a and over 10 a. In the high-latitude zone, off China, in North America north of 40°N and the coast of Japan, the annual period oscillation occupies a dominant position in the various period components.

Trend analysis of relative sea level rise or fall of the tide gauge stations in the Pacific

On the basis of the analytical results of the period components of monthly mean sea level of 236 stationsin the Pacific, the period components plus linear trend are ed to fit the monthly mean sea level series. The statisticalresults of linear trend Coefficients of these stations indicate that, if the abnormal values of sea-level rise and fall are neglected, the average rise rate of relative sea level in the Pacific is 1. 16 mm/a. Affected by nonuniformity Of land subsidence and other factors, the regional change of relative sea level rise or fall in the Pacific is greater. In the light of thepositive or negative values of linear trend coefficients as well as the geographical position of the sea area, zoning is madeof the sea level rise or fall in the Pacific including the coastal areas of China and Southeast Asia to obtain the averagerate of rise or fall in each sea area. The rise or fall trends of relative sea level obtained for the entire Pacific Ocean,west coast of North America, the northern and central South America, the greater part of the tropical Pacific and thecoastal Islands of Japan are basically in keeping with the other relevant results. The regional average estimated result ofthe relative sea level in the coast of East Asia is on the rise while the estimated results provided by Barnett tend todrop; the main cause of this nonuniformity is the number of stations selected and the distributional density.

Research on the spectral analysis and testmethod of period signals in monthly mean sea level

This paper summarizes the general methods,existing problems and their causes of the period analysis for the monthly mean sea level and points out that it is the key to the analysing period signals and forecasting the change trend of the monthly mean sea level that the periods of the signals are selected reasonably. As there are often many period signals in these series, nonlinear effects exist between pairs of period signals. In order to avoid the false periods that may be introduced due to the effects of side lobes and the periods with statistical phase significance coherence that may be introduced due to the effects of nonlinear effects and their restraint to other period signals, the maximum entropy spectral analysis and the corresponding significance period test may be performed repeatedly on the basis of the bispectrum analysis and meanwhile the most significant period component is filtered out by the least square filtering method, i. e., the method of the significance period analysis with mixed spectra modeled by a nonlinear system is adopted and the signal periods approaching the reality are selected one by one. The examples of the bispectrum analysis, the signal period analysis by mixed spectra and the fitting parameters for combined period components with linear trend in the time series of monthly mean sea level are given in this paper.

数字化水平对企业碳绩效的非线性影响——绿色技术创新的中介作用

基于数字化战略与“双碳”目标,从数字化建设、应用和发展3个维度探讨数字化水平对企业碳绩效的非线性影响机理以及绿色技术创新在其中的中介传导机制,选取2010—2020年中国工业企业数据和动态GMM模型进行实证检验。结果表明,数字化建设、应用和发展水平均与企业碳绩效之间呈先抑后扬的U型关系,大多数中西部省份的数字建设与应用水平未跨过拐点,对企业碳绩效的影响尚处于抑制阶段,而东部和少数中西部省份的数字化发展水平已跨过拐点,对企业碳绩效具有显著促进效应;发明型、改进型绿色技术创新均在数字化建设、应用和发展水平与企业碳绩效之间起部分中介作用。中介效应分解发现,与改进型绿色技术创新相比,发明型绿色技术创新在数字化水平各维度与企业碳绩效之间的中介作用更显著。经过变换数据年份等稳健性检验后,上述结论仍然成立。

Sliding Mode Control, with Integrator, for a Class of Mimo Nonlinear Systems

In this paper, the robust control problem of general nonlinear multi-input multi-output (MIMO) systems is proposed. The robustness against unknown disturbances is considered. Two algorithms based on the Sliding Mode Control (SMC) for nonlinear coupled multi-input multi-output (MIMO) systems are proposed: the first order sliding mode control (FOSMC) with saturation (sat) function and the FOSMC with sat combined with integrator controller. Those algorithms were simulated and implemented on the three tanks test-bed system and the exprimental results confirm the effectiveness of our control design.

Computation of Error in Estimation of Nonlinearity in ADC Using Histogram Technique

Computation of error in estimation of nonlinearity in ADC using histogram test are reported in this paper. Error determination in estimation of Differential Nonlinearity (DNL) and Integral Nonlinearity (INL) of an ADC is done by taking deviation of estimated value from actual value. Error in estimated INL and DNL is determined to check the usefulness of basic histogram test algorithm. Arbitrary error is introduced in ideal simulated ADC transfer characteristics and full scale simulated sine wave is applied to ADC for computation of error in estimation of transition levels and nonlinearity. Simulation results for 5 and 8 bit ADC are pre-sented which show effectiveness of the proposed method.