Stability of weighted spectral distribution in a pseudo tree-like network model

The comparison of networks with different orders strongly depends on the stability analysis of graph features in evolving systems. In this paper, we rigorously investigate the stability of the weighted spectral distribution（i.e., a spectral graph feature） as the network order increases. First, we use deterministic scale-free networks generated by a pseudo treelike model to derive the precise formula of the spectral feature, and then analyze the stability of the spectral feature based on the precise formula. Except for the scale-free feature, the pseudo tree-like model exhibits the hierarchical and small-world structures of complex networks. The stability analysis is useful for the classification of networks with different orders and the similarity analysis of networks that may belong to the same evolving system.

Thermal-hydraulic modeling and analysis of hydraulic system by pseudo-bond graph

To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.

A 3-DOF Pseudo-Rigid-Body Model for Tension-Based Compliant Bistable Mechanisms

Compliant bistable mechanisms, devices with two distinct stable equilibrium positions, are used in a variety of applications, such as switches, clasps, and valves. Many kinds of compliant bistable mechanisms were proposed and studied during the past decade. Among them, tension-based compliant bistable mechanisms, that incorporate tension pivots as their flexible members, feature in short travel distance and low power consuming. So far, the design of this kind of bistable mechanisms is done using finite element method through trial and error, thus is time-consuming. By treating the tension pivots as fixed-guided segments and their elongation as a spring, we developed a novel three degree-of-freedom （3-DOF） pseudo-rigid-body model （PRBM） for this kind of bistable mechanisms. The principle of virtual work is used to derive the force-deflection relationship of the PRBM model. The comparison between the PRBM results and the experimental results of the force-deflection characteristics shows that the PRBM can predict not only the bistable behavior of the tension-based bistable mechanisms, but also their soft spring-like post-bistable behavior and the spring-like force-deflection characteristics when pulling in the reverse direction from the as-fabricated position, which is called reverse behavior. The 3-DOF PRBM can be used to design and identify tension-based bistable mechanisms. Using the PRBM instead of the trial-and-error method can greatly reduce the development time of this kind of bistable mechanisms.

Pseudo-invariant Eigen-operator for Deriving Energy-Level Gap for Jaynes-Cummings Model

我们通过分析标准 Jaynes-Cummings 模型扩大不变的 eigen 操作员的概念到 pseudo-invarianteigen-operator 大小写。我们以这个模型的超级对称的发电机发现 thepseudo 不变的 eigen 操作员，哪个到为 Jaynes-Cummings Hamiltonian 的精力级的差距的 diretlyleads。

Weighted Pseudo Almost Periodic Solutions for a Class of Hematopoiesis Model with Time-Varying Delay

In this paper, firstly, a notion of a class of generalized weighted pseudo al- most periodic function is introduced, then we investigate some basic and essential properties of the space that consists of these functions. Finally, we study the exis- tence of weighted pseudo almost periodic solutions to hematopoiesis model with time- varying delay.

Long-distance propagation of pseudo-partially coherent Gaussian Schell-model beams in atmospheric turbulence

Propagation properties of spatially pseudo-partially coherent Gaussian Schell-model beams through the atmo- spheric turbulence over a long-distance uplink path are studied by numerical simulation. A linear coordination trans- formation is introduced to overcome the window effect and the loss-of-resolution problem. The beam spreading, beam wandering, and intensity scintillation as functions of turbulence strength, source correlation length, and change fre- quency of random phase that models the partial coherence of the source are analyzed. It is found that the beam spreading and the intensity scintillation of the partially coherent beam are less affected by the turbulence than those of the coherent one, but it suffers from a more severe diffractive effect, and the change frequency of random phase has no evident influence on it. The beam wandering is insensitive to the variation of source correlation length, and decreases firstly then goes to a fixed value as the change frequency increases.

Pseudo-invariant Eigen-Operator Method for Solving Field-Intensity-Dependent Jaynes-Cummings Model

By using the pseudo invariant eigen-operator method we analyze the field-intensity-dependent JaynesCumming (JC) model. The pseudo-invariant eigen-operator is found in terms of the supersymmetric generators. Theenergy-level gap of this JC Hamiltonian is derived. This approach seems concise.

Large Eddy Simulation of Pseudo-Shock Waves Using Wall Model

A supersonic turbulent flowfield involving the pseudo-shock waves in an isolator of a supersonic combustion ramjet is computed using two different LES codes which are a high-order upwind finite volume scheme, and a sixth order compact differencing scheme utilizing the localized artificial diffusivity method for stabilizing shock waves and employing a wall model to enable the use of coarse mesh. In the validation study where a supersonic turbulent boundary layer flow over a flat plate is examined, both LES codes are well validated using velocity profile in the boundary layer given by the hot-wire anemometry and normal stress given by the laser Doppler anemometry. In particular, the sixth order compact differencing scheme gives closer agreements with these experimental data. Then, the validated LES codes are applied to solve the Mach number 2.5 supersonic turbulent flowfield involving the pseudo-shock waves. It is shown that typical features of unsteady flowfield of the pseudo-shock waves are well obtained by both schemes. Again, it is indicated that the sixth order compact differencing scheme gives closer agreements with the existing velocity data obtained by particle image velocimetry and pressure fluctuation data on the wall surface. Besides, the computational cost of the compact differencing scheme is found to be 1/7 of that for the upwind finite volume scheme, even though a wall model is solved at each grid point on the wall surface. Therefore, the obtained results in the present study allow recommending the sixth order compact differencing scheme with a wall model for simulating supersonic turbulent flowfield in an isolator involving the pseudo-shock waves.

Asymptotic Normality of Pseudo-LS Estimator of Error Variance in Partly Linear Autoregressive Models

Consider the model Y_t=βY_t-1+g(Y_(t-2))+ε_t for 3＜=t＜=T.Here g is an unknown function,βis an unknown parameter,ε_t are i.i.d,random errors with mean 0 and varianceσ~2 and the fourth momentα_4,andε_t are independent of Y_s for all t＞=3 and s=1,2. Pseudo-LS estimators■_T^2,■4T and■_T^2 ofσ~s,α_4 and Var(ε_3~2)are respectively constructed based on piecewise polynomial approximator of g.The weak consistency of■4T and■_T^2 are proved.The asymptotic normality of■_T^2 is given,i.e.T^(1/2)(■_T^2-σ~2)/■_T converges in distribution to N(0,1).The result can be used to establish large sample interval estimates ofσ~2 or to make large sample tests forσ~2.

基于降维机理模型的储能电池安全充电在线控制技术

大倍率充电会引起储能电池负极析锂,进一步可能会诱发电池热失控并导致安全事故。而析锂副反应与电池负极电位直接相关,通过模型精确预测负极电位,传输至储能电池管理系统调整充电工况,可以有效抑制负极析锂。因此,文中提出一种基于降维机理简化伪二维(simplified pseudo two-dimensional,SP2D)模型的储能电池安全充电在线控制技术。首先,对伪二维(pseudo two-dimensional,P2D)模型中部分偏微分方程进行降维简化,建立SP2D模型,同时采用不同的方法获取相应的模型参数。其次,使用实验数据的端电压和负极电位对模型进行验证,结果表明模型在不同倍率恒流工况下精度较高。再次,基于SP2D模型结合比例控制器开展电池无析锂安全充电的仿真工作,结果表明,电池经过1895 s充电即达到截止电压4.3 V,且充电过程中负极电位均处于无析锂安全电位区间。最后,对仿真得到的充电策略进行循环和拆解验证,结果表明提出的充电方法能够实现电池无析锂安全充电。

η坐标系下假不可压大气模式动力框架改进

发展高分辨区域中尺度天气预报模式是改进暴雨落区预报的一个重要途径。区域中尺度模式空间分辨率达到100 m,对当前计算资源提出了严峻挑战。一种可行的解决方案是发展滤除声波的模式替代全弹性模式。滤除声波的模式可以使用较大的时间步长积分,能显著提高积分效率。作者在2018年利用一种声波滤除理论——假不可压理论,初步在地形追随质量坐标系(η坐标系)下建立了假不可压模式。数值试验表明模式的结果是合理可信的,然而关键问题是没有滤除声波。本文改进了假不可压模式,建立新的假不可压模式干动力框架。新动力框架控制方程的关键改进是使用椭圆方程求解扰动气压,理论上保证了声波的滤除。新动力框架的时间积分方案更简洁,不使用时步分裂算法。对比改进的假不可压模式和WRF(Weather Research and Forecasting)模式的干热泡对流数值试验结果,发现假不可压模式获得了与WRF模式相似的动力场和热力场分布,且模拟的气压扰动时间序列平滑,说明声波已被滤除,相比2018版本的假不可压模式,这是较大的改进。

底水油藏水侵量计算新方法

针对底水油藏的开发,在缺乏试井数据的情况下采用常规油藏物质平衡法以及试井分析方法均难以确定水驱控制储量,进而无法获得水体参数和特征来计算油田的水侵量。为了更加准确的预测水驱油田水侵量,结合生产动态资料,选择符合的水驱特征曲线计算水驱控制储量。在此基础上,考虑油环油、溶解气、水体等因素,建立物质平衡方程,通过亏空体积曲线法计算获得水侵量。利用Fetkvoitch拟稳态模型,采用试错法,优化计算水体体积和水侵系数,保证Fetkvoitch拟稳态模型求解的水侵量和亏空体积曲线法求解的水侵量最接近,得到最优的水体体积和水侵系数对未来生产动态中水侵量进行预测。运用油藏数值模拟软件建立的模型与本文提出两种的计算方法拟合结果对比可知的水体体积的误差为2.6%、水侵指数的误差为2.2%,计算结果准确,为底水油藏计算水侵量提供了可靠的依据,并为预测水侵量提供了新的方法。

基于R-L分数阶定义的PCCM Boost变换器建模与分析

研究了基于R-L分数阶定义的电感电流伪连续PCCM(pseudo-continuous conduction mode)Boost变换器模型,并由此导出了变换器的状态平均模型,然后推导出升压比,直流静态工作点,电感电流波纹以及输出电压波纹的表达式。结果表明,与基于Caputo分数阶定义下的变换器模型相应表达式比较,R-L分数阶定义下的直流静态工作点和升压比不仅与占空比相关,而且还与电感和电容的阶数有关,输出电压波纹的表达式不仅与分数阶电感的阶数α有关,与分数阶电容的阶数β也相关。电感和电容的阶数对状态变量的直流分量和分数阶PCCM Boost的稳态特性有很大影响。最后,在MATLAB/SIMULINK中搭建了R-L分数阶PCCM Boost变换器数学模型和电路模型,仿真结果显示R-L分数阶PCCM Boost变换器模型的分析结果比其他PCCM Boost模型的分析结果更加稳定,误差更小。

基于精确子域模型法的表贴式直线电机永磁体磁场解析

在永磁同步电机的设计工作中,磁场解析计算是一项十分重要的工作。为此,针对表贴式直线电机永磁体的磁场开展了解析建模工作。首先,将伪周期法与精确子域法相结合,求解出了在特定伪周期下的永磁体虚拟阵列的磁场分布解析式;其次,使伪周期趋近无穷,利用傅里叶级数与傅里叶变换之间的对应关系,求得单个永磁体的磁场分布解析式,并借助有限元方法仿真验证了其准确性;再次,利用永磁体的磁场分布解析式,推导了一类表贴式直线电机的永磁体阵列的磁场分布解析式,实现了对于表贴式直线电机磁场的精确刻画;最后,利用有限元方法仿真验证了准确性。

基于伪解析法的TTI介质纯qP波地震波场正演模拟

近年来,各向异性介质纯qP波正演模拟及逆时偏移成像技术受到广泛关注。常规拟声波方程存在伪横波干扰、受模型参数限制(ε≥δ)、传播不稳定和计算精度不高等因素影响,极大地限制了其应用。为此,本文将qP波拟微分方程变换到空间—波数域,并通过坐标变换,推导了时间域TTI介质二阶纯qP波波动方程;为提高计算精度,引入伪解析算法(pseudo analytical method, PAM),实现了基于伪解析法的TTI介质纯qP波地震波场正演模拟。数值模拟结果表明:(1)本文方法克服了拟声波方程的局限性,消除了伪横波干扰,不受模型参数限制且地震波场能稳定传播;(2)与其他方法相比,伪解析法能有效提高数值模拟精度;(3)简单及复杂模型测试验证了本文方法的正确性与适用性。

北斗卫星船载导航信号并行捕获算法

信号捕获作为实现北斗卫星船载导航的第一阶段,也是最重要的一环,为此研究基于北斗卫星船载导航信号并行捕获算法,在短时间内捕获卫星信号,为船舶提供高精度的定位和导航服务。建立北斗卫星导航信号模型,依据模型生成的北斗卫星导航信号,采用傅里叶变换(Fast Fourier Transformation,FFT)算法以及快速傅里叶逆变换(Inverse Fast Fourier Transform,IFFT)算法,通过并行频率搜索和并行码相位搜索分别将伪随机码相位、载波频移的二维搜索变成一维进行并行搜索,获取北斗卫星信号的伪随机码和载波频移,实现北斗卫星船载导航信号并行捕获。实验结果表明,该算法可以成功地捕获船载导航信号,并且捕获耗时短;对船载导航信号的载波频率估计误差小。

基于村镇建筑的新型沙漠砂混凝土砌块墙体的抗震性能研究

利用沙漠砂研发的蒸压加气混凝土砌块是一种新型砌体材料。为了研究这种新型砌块在村镇建筑中的应用,考虑在不同竖向压应力和构造柱的约束作用下,对4片沙漠砂蒸压加气混凝土砌块墙体开展拟静力试验,通过对比分析4片墙体在低周反复荷载作用下的破坏特性、力-位移曲线、骨架曲线、刚度退化曲线及延性等性能指标。结果表明:1)墙体主要以剪切破坏为主,未设置构造柱墙体主裂缝沿约45°贯彻整个墙体,设置构造柱墙体主裂缝呈“倒八”字型,且当竖向压应力增大时,墙体的抗震承载力也随之增大,抗侧刚度有所提高,但延性随之减小;2)竖向压应力相同情况下,对比分析表明设置构造柱墙体的极限承载力约是素墙体的2.22倍,延性提高了约60%,且刚度也有所提升;3)基于主拉应力理论和库仑破坏理论分别建立了适用于该新型砌块墙体的抗震承载力计算公式,且库仑破坏理论建立的抗震承载力计算公式应用更合理;4)建立了恢复力模型骨架曲线,能够较好地反映沙漠砂蒸压加气混凝土砌块墙体的试验特点。

基于格子玻尔兹曼方法的横向交变质量力对核沸腾影响的数值分析

采用格子玻尔兹曼方法的单组份伪势模型与有限差分耦合的混合热格子玻尔兹曼模型,对在横向交变质量力作用下的单汽泡核态沸腾过程进行了研究,探讨了在不同接触角和过热度下,横向交变质量力的振幅和交变频率对汽泡脱离底壁的脱离特性的影响。结果表明,施加横向交变质量力会造成汽泡脱离直径减小,同时加速汽泡脱离底壁。其次,壁面越疏水,汽泡的脱离行为受到横向交变质量力的影响越大;壁面过热度越大,汽泡的脱离行为受到横向质量力的影响也越大。另外,在模拟工况下,当横向交变质量力的振幅大于0.01时,添加横向交变质量力会使汽泡的脱离直径与脱离周期均减小;而横向交变质量力的交变频率仅在某一频段时,使得汽泡的脱离周期减小。

一种自复位摇摆墙的改进Bouc-Wen滞回模型

Bouc-Wen模型是一种可表征结构及构件刚度、强度退化等的多功能非线性光滑滞回模型,可广泛应用于各类结构滞回行为的描述。自复位摇摆墙(Self-centering rocking wall, SCRW)结构由于其优越的抗震和自复位性能,滞回曲线呈“旗帜型”。为了更好地表征这种“旗帜型”滞回特性,在Bouc-Wen模型的基础上,建立一种具有较高精度和较好实用性的改进Bouc-Wen滞回模型。改进的Bouc-Wen模型参数是决定结构滞回性能力学特征的关键。由于该模型参数众多且选择范围不明确,为适应该类模型参数高效识别的需求,通过在MATLAB/Simulink环境中搭建程序框图,实现了对该理论模型控制参数的定性及定量分析,并运用遗传算法对10个SCRW试验结果进行参数识别,对识别结果进行统计分析,建立各参数与滞回曲线关键点的关系式,基于统计结果给出了各参数的建议取值范围;最后,通过SCRW拟静力试验对改进的滞回模型和参数取值范围进行了验证。结果表明:这种单自由度改进的Bouc-Wen滞回模型能较好地反映SCRW在往复荷载作用下无残余变形和强度、刚度退化特点的“旗帜型”滞回特性。所提出的参数取值范围显著提升了改进Bouc-Wen模型的识别精度与效率,识别过程对类似模型的参数识别具有参考价值。

大数据背景下社交平台伪健康信息传播影响因素研究

探究大数据背景下社交平台伪健康信息传播影响因素,为有关部门更好地制定伪健康信息管理策略提供参考与借鉴。整合S-O-R模型和MOA理论,引入个性化推荐这一新变量,构建社交平台伪健康信息传播影响因素模型,利用问卷调查和结构方程模型验证模型和假设的合理性。研究表明信息交换、健康关注度、信息质量、信息新颖和个性化推荐正向影响用户感知,进而正向影响用户伪健康信息传播行为,而健康信息素养负向影响用户伪健康信息传播行为,并据此提出管理社交平台伪健康信息传播的可行性建议。