基于时间演化响应面模型的JWL状态方程参数标定方法

综合试验数据和建模与模拟结果,标定爆轰产物JWL(Jones-Wilkins-Lee)状态方程中的唯象参数,对理解爆轰膨胀驱动过程和评价做功能力至关重要。时间演化代理模型能构建重要参数与系统响应量(system response quantity,SRQ)之间较为简洁的函数关系,为描述爆轰动力行为和参数标定提供一种快速高精度算法。本文首先利用拉丁超立方抽样(Latin hypercube sampling,LHS)技术对爆轰产物JWL状态方程中的不确定参数进行抽样,选取有效数据并分成两组:第一组进行高分辨率仿真,使用具有自主知识产权爆轰数值软件CFD2D计算得到径向壁位置和径向壁速度,输出结果用于构建不确定JWL参数和SRQ之间的时间演化响应面模型;第二组用于评估时间演化代理模型的精确度。其次,定义代理模型与试验数据之间的残差,进而搜索最小残差获得最优参数。结果表明:将最优参数代入高分辨率模型后导出的SRQ的输出结果和试验数据吻合较好,从而完成了参数标定和模型确认。结果为武器型号设计和装备性能评估提供依据。

基于背景估计的合成孔径声呐图像自动均衡方法

为了解决合成孔径声呐图像远近灰度不均衡,对比度低,图像判别困难等问题,提出了一种基于图像的局部邻域和距离向相结合的自适应背景估计的均衡方法。首先提出了基于照度模型的均衡模型,然后通过非均衡时间演化模型和构造均衡函数计算图像的差分来估计背景分量,并在迭代过程中通过残余能量大小自动优化参数和判断迭代终止,最后通过照度模型得到均衡结果。通过实际数据验证和分析,发现经过均衡处理后的声呐图像,其背景更加真实,对比度提高,目标和纹理得到增强,同时,噪声和其他干扰信号也得到了有效的抑制。算法在图像的局部均衡性、信息量大小、细节丰富度、进一步验证了该算法的实用性和有效性。

局部背景变分迭代下的合成孔径声呐图像自适应均衡

针对合成孔径声呐图像存在的局部灰度畸变、对比度不高、目标被掩盖等问题,提出一种自适应均衡增强处理方法。首先,通过变分理论建立图像域非均衡时间演化模型;然后,利用声呐图像的局部信息及均衡时间演化过程中相邻时刻图像的差分关系,构建指数加权形式的均衡函数,并在迭代过程中进行权系数自动更新和背景分量估计;最后,通过背景均衡和动态范围调整得到均衡结果。实际数据验证和分析结果表明:均衡后的声呐图像背景变得更平整,对比度提高,目标与纹理得到增强,噪声等干扰也得到有效抑制;相较于对比算法,图像的局部均衡性、等效视数、峰值信噪比、局部结构相似性等均表现最优,实用性和有效性得到保证。

How Well does BCC_CSM1.1 Reproduce the 20th Century Climate Change over China?

The historical simulation of phase five of the Coupled Model Intercomparison Project （CMIP5） ex- periments performed by the Beijing Climate Center cli- mate system model （BCC_CSM1.1） is evaluated regard- ing the time evolutions of the global and China mean sur- face air temperature （SAT） and surface climate change over China in recent decades. BCC CSM1.1 has better capability at reproducing the time evolutions of the global and China mean SAT than BCC_CSM1.0. By the year 2005, the BCC_CSM1.1 model simulates a warming am- plitude of approximately I℃ in China over the 1961- 1990 mean, which is consistent with observation. The distributions of the warming trend over China in the four seasons during 1958-2004 are basically reproduced by BCC CSM1.1, with the warmest occurring in winter. Al- though the cooling signal of Southwest China in spring is partly reproduced by BCC_CSM1.1, the cooling trend over central eastern China in summer is omitted by the model. For the precipitation change, BCC_CSM1.1 has good performance in spring, with drought in Southeast China. After removing the linear trend, the interannual correlation map between the model and the observation shows that the model has better capability at reproducing the summer SAT over China and spring precipitation over Southeast China.

Projection of PM_(2.5) and Ozone Concentration Changes over the Jing-Jin-Ji Region in China

Based on GISS-E2-R model simulations, the changes in PM2.5 and ozone concentrations during 2016– 35 are analyzed over the Jing-Jin-Ji region under different future emissions scenarios: 2.6, 4.5, 6.0, 8.5 Representative Concentration Pathways scenarios(RCP2.6, RCP4.5, RCP6.0, and RCP8.5), compared to the baseline periods of 1851–70(pre-industrial) and 1986–2005(present day). The results show that PM2.5 increases under all emissions scenarios, with the maximum value occurring in the southeastern part of the region under most scenarios. As for ozone, its concentration is projected to increase during 2016–35 under all emissions scenarios, compared to the baseline periods. The temporal evolutions of PM2.5 and ozone show PM2.5 reaching a peak during 2020–40, while ozone will likely increase steadily in the future.

Time-Dependent Evolution of Two Coupled Luttinger Models of Spin-1/2 Fermions

Based on the field-theoretical bosonization we consider the spinful system consisting of two disconnected Luttinger liquids, which are coupled at time t = 0 through chiral density-density interactions. We show the wellknown spin-charge separation in this 1D system by means of bosonization and Bogoliubov transformation. To evaluate analytically the one-particle equal-time correlation functions, Cazalilla＇s methods are extended to spin-charge sectors. It is found that in long time limit the behavior of correlations does not coincide with that of equilibrium equal-time correlations of two coupled spinful Luttinger liquids. In order to compare with experimental results, the improved exponent that governs the power-law behavior of equal-time correlations of the non-equilibrium system is obtained at the end of this work.

Scaling in Rate-Changeable Birth and Death Processes with Random Removals

We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I（t）k or lose one monomer at a rate J（t）k, and with a probability P（t） an aggregate of any size is randomly removed. We then anedytically investigate the kinetic evolution of the model by means of the rate equation. The results show that the scaling behavior of the aggregate size distribution is dependent crucially on the net birth rate I（t） - J（t） as well as the birth rate I（t）. The aggregate size distribution can approach a standard or modified scaling form in some cases, but it may take a scale-free form in other cases. Moreover, the species can survive finally only if either I（t） - J（t） ≥ P（t） or [J（t） ＋ P（t） - I（t）]t ≈ 0 at t ≥ 1; otherwise, it will become extinct.

Decoherence Effect in An Anisotropic Two-Qubit Heisenberg XYZ Model with Inhomogeneous Magnetic Field

Taking the decoherence effect into account, the entanglement evolution of a two-qubit anisotropic Heisenberg XYZ chain in the presence of inhomogeneous magnetic field is investigated. The time evolution of concurrence is studied for the initial state cos θ｜01） ＋ sin θ｜10） at zero temperature. The influences of inhomogeneous magnetic field, anisotropic parameter and decoherence on entanglement dynamic are addressed in detail, and a concurrence formula of the steady state is found. It is shown that the entanglement sudden death （ESD） and entanglement sudden birth （ESB） appear with the decoherence effect, and the stable concurrence depends on the uniform magnetic field B, anisotropic parameter △ and environment coupling strength γ, which is independent of different initial states and nonuniform magnetic field b.

Modeling to predict the time evolution of negative bias temperature instability(NBTI) induced single event transient pulse broadening

An analytical model is proposed to calculate single event transient (SET) pulse width with bulk complementary metal oxide semiconductor (CMOS) technology based on the physics of semiconductor devices. Combining with the most prevalent negative bias temperature instability (NBTI) degradation model, a novel analytical model is developed to predict the time evolution of the NBTI induced SET broadening in the production, and NBTI experiments and three-dimensional numerical device simulations are used to verify the model. At the same time, an analytical model to predict the time evolution of the NBTI induced SET broadening in the propagation is also proposed, and NBTI experiments and the simulation program with integrated circuit emphasis (SPICE) are used to verify the proposed model.

On Models of Nonlinear Evolution Paths in Adiabatic Quantum Algorithms

In this paper,we study two different nonlinear interpolating paths in adiabatic evolution algorithms for solving a particular class of quantum search problems where both the initial and final Hamiltonian are one-dimensional projector Hamiltonians on the corresponding ground state.If the overlap between the initial state and final state of the quantum system is not equal to zero,both of these models can provide a constant time speedup over the usual adiabatic algorithms by increasing some another corresponding "complexity".But when the initial state has a zero overlap with the solution state in the problem,the second model leads to an infinite time complexity of the algorithm for whatever interpolating functions being applied while the first one can still provide a constant running time.However,inspired by a related reference,a variant of the first model can be constructed which also fails for the problem when the overlap is exactly equal to zero if we want to make up the "intrinsic" fault of the second model - an increase in energy.Two concrete theorems are given to serve as explanations why neither of these two models can improve the usual adiabatic evolution algorithms for the phenomenon above.These just tell us what should be noted when using certain nonlinear evolution paths in adiabatic quantum algorithms for some special kind of problems.

On a Nonlinear Model in Adiabatic Evolutions

In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using.