MPEG-2先进音频编码(AAC)的研究和软件仿真

ＭＰＥＧ－２ＡＡＣ是ＩＳＯ／ＩＥＣ ＭＰＥＧ组织继 ＭＰＥＧ－１、ＭＰＥＧ－２音频编解码标准后,制定 的最新国际标准（ＩＳＯ／ＩＥＣ １３８１８－７）,在６４ｋｂｐｓ／每声道低码率时能提供全透明音质。本文对其编 解码算法进行了简要介绍。论文作者对ＭＰＥＧ－２ＡＡＣ进行了软件仿真,文中介绍了仿真结果,仿 真时对ＡＡＣ标准所附编码范例中的一些不妥之处,作了改进,文中列举了６方面的修正。     

C2分子的分析势能函数与垂直电离势

用ａｂｉｎｉｔｉｏ计算方法和实验光谱数据分别导出Ｃ２分子基态Ｘ１Σ＋ｇ和激发态ｄ３Πｇ的Ｍｕｒｅｌ－Ｓｏｒｂｉｅ函数，同时用ＱＣＩＳＤ／６－３１１Ｇ方法优化出Ｃ－２、Ｃ＋２、Ｃ２＋２分子离子基态的平衡核间距，算出Ｃ２分子的垂直电离势，计算数据与实验光谱数据进行了比较。     

MPEG-2先进音频编码(AAC)的研究和软件仿真

ＭＰＥＧ－２３ＡＡＣ是ＩＳＯ／ＩＥＣＭＰＥＧ组织继ＭＰＥＧ－１,ＭＰＥＧ－２音频编解码标准后,制定的最新国际标准（ＩＳＯ／ＩＥＣ１３８１８－７）在６４ｋｂｐｓ／每声道低码率时能提供全透明音质,本文对其编解码算法进行了简要介绍,论文作者对ＭＰＥＧ－２ＡＡＣ进行了软件仿真,文中介绍了仿真结果,仿真时对ＡＡＣ标准所附编码范 中的一些不妥之处,作了改进,文中列举了６方面的修正。     

N_2分子X~1Σ_g~ ,A~3Σ_u~ 和B~3Π_g的势能函数

用文献［１，２，８］介绍的方法推导了Ｎ２分子的基态（Ｘ１Σ＋ｇ）和激发态（Ａ３Σ＋ｕ和Ｂ３Πｇ）的合理离解极限。计算并比较了在６－３１１Ｇ基集合，ＵＨＦ、ＣＩＤ、ＵＣＩＳＤ和ＱＣＩＳＤ水平下Ｎ２分子上述三个电子态的平衡结构和谐振频率；并用ＱＣＩＳＤ／６－３１１Ｇ计算了各态的系列单点势能值，由正规方程组拟合Ｍｕｒｒｅｌ－Ｓｏｒｂｉｅ函数得到了相应各态的完整势能函数，结果与实验数计算值符合得比较好。     

N2分子X^1Σg^＋,A^3Σu^＋和B^3Пg的势能函数

用文献［１，２，８］介绍的方法推导了Ｎ２分子的基态（Ｘ＾１Σｇ＾＋）的激发态（Ａ＾３Σｕ＾＋和Ｂ＾３Пｇ）的合理离解极限。计算并比较了在６－３１１Ｇ＾＊基集合，ＵＨＦ、ＣＩＤ、ＵＣＩＳＤ和ＱＣＩＳＤ水平下Ｎ２分子上述三个电子态的平衡结构和谐振频率；并用ＱＣＩＳＤ／６－３１１Ｇ＾＊计算了各态的系列单点势能值，由正规方程组拟合Ｍｕｒｒｅｌｌ－Ｓｏｒｂｉｅ函数得到了相应各态的完整势能函数，结果与实验数计     

LaH分子的X1∑+态的势能函数

应用原子分析反应静力学原理导出ＬａＨ分子的电子状态和可能的离解极限,考虑相对论紧致有效势ＰＣＥＰ（Ｒｅｌａｔｉｖｉｓｔｉｃ Ｃｏｍｐａｃｔ Ｅｆｆｅｃｔｉｖｅ Ｐｏｔｅｎｔｉａｌ）近似下,用ＱＣＩＳＤ方法计算了ＬａＨ分子基态Ｘ＾１Σ＾＋的平衡几何Ｒｅ和离解能Ｄｅ为２．１２５Ａ和２．６２３ｅＶ,并在计算出来的一系列背地里点势能基础上,用正规方程组拟合Ｍｕｒｒｅｌｌ－Ｓｏｒｂｉｅ（Ｍ－Ｓ）势能函数,得     

S2分子X^3—Σ^—g和B^3Σ^—u态的势能函数和振动光谱特征

应用实验光谱数据，导出了Ｓ２的基态分子Ｘ３Σ－ｇ和激发态Ｂ３Σ－ｕ的ＭｕｒｅｌＳｏｒｂｉｅ势能函数，并用ＱＣＩＳＤ（Ｔ）／６－３１１Ｇ方法对基态进行了计算，结果在吸引支出现了回避相交而产生了一个浅平极大，其他部位与实验结果符合甚好。计算了Ｂ３Σ－ｕ和Ｘ３Σ－ｇ态的全部振动能级，以及激发态（Ｂ３Σ－ｕ）振动能级≤９和基态（Ｘ３Σ－ｇ）振动能级≤３０之间的Ｄｅｓｌａｎｄｒｅｓ表。给出了Ｂ３Σ－ｕ－Ｘ３Σ－ｇ跃迁Ｃｏｎｄｏｎ抛物线，各振动态的计算结果与实验值很好符合。     

[Mo3S7]分子簇和聚合簇合物的振动光谱和电子光谱

本文报道了分立簇「Ｍｏ３Ｓ７（ｄｔｐ）３Ｉ」１及它的四聚物｛「Ｍｏ３ＳＵ（ｄｔｐ）３」４Ｉ｝．｛（ＨｇＩ３）４．Ｋ｝２（ｄｔｐ＝Ｓ２Ｐ（ＯＣ２Ｈ５）＾－２的ＩＲ,Ｒａｍａｎ和ＵＶ－Ｖｉｓ光谱,并讨论分立的「Ｍｏ３Ｓ７（ｄｔｐ）３Ｉ」在四聚后这些光谱的变化。     

在小硅化物SiX~m（X＝Be、B、C、N、O、F、Ne，m＝～4－＋2）中分子成键倾向的从头算研究

此文用从头计算法，在ＨＦ、ＭＰ２、ＭＰ３水平下，使用基组６—３１Ｇ、６—３１＋Ｇ对ＳｉＯ的等电子分子ＳｉＸｍ（Ｘ＝Ｂｅ、Ｂ、Ｃ、Ｎ、Ｐ、Ｎｅ，ｍ＝－４～＋２）进行了几何优化，并计算了相应的平衡几何构型下的振动频率，对ＳｉＯ分子，使用ＱＣＩＳＤ（Ｔ）方法考虑了不同水平下的电子相关效应，并考虑了不同基函数６－３１＋Ｇ和６－３１１＋Ｇ的影响。计算结果表明，所有分子的势能曲线都有稳定的极小值，并且键长与频率在ＨＦ、ＭＰ２、ＭＰ３水平上都呈现出明显的规律性，通过与实验上存在的稳定分子ＳｉＯ相比较，可以预言ＮＳＩｉ－和ＳｉＦ＋比其它分子有较明显的成键可能性，所以，ＮＳｉ－和ＳｉＦ＋有可能形成稳定的分子。     

角分辨XPS对自组装单分子层厚度和官能团位置的定性及定量研究

用角分辨ＸＰＳ（Ａｎｇｌｅ－ｒｅｓｏｌｖｅｄＸＰＳ）研究研究了ＨＳ（ＣＨ２）１０ＣＯＯＨ（Ｉ）ＨＳ（ＣＨ２）３ＯＣ６Ｈ４Ｎ＝ＮＣ６Ｈ４（ＣＨ２）７ＣＨ３（ＩＩ）和ＨＳ（ＣＨ２）６ＨＳ（Ⅲ）３种分子在Ａｕ膜表面制备的自组装单分子层，得出了（Ｉ）中Ｓ原子，（Ⅱ）中Ｓ，Ｎ原子距膜表面的垂直距离，并结合构象分析确定了分子的取向和倾角，对分子（Ⅲ）则得出分子在紫外光照射下氧化反应的选择性，发现氧化主要在底层     

Reducing slab track vibration into bridge using elastic materials in high speed railway

In this paper, the problem of vibration transmission from slab track structures into bridge is studied by theoretical analysis. A vehicle-track-bridge coupling system dynamics model is established based on a multibody dynamics theory and a finite element method. The system model consists of vehicle model, track-bridge model and wheel/rail interaction model. The vehicle model is established based on the multibody dynamics theory, and the tack-bridge model is established by the finite element method. The vehicle model and track-bridge model are coupled through wheel/rail interaction model, and the track irregularities are included. The system dynamic responses are calculated, and the effectiveness of elastic materials in vibration reducing is discussed. The results demonstrate that elastic materials like slab mat layer inserted between slab track and bridge can reduce vibration transmitted from track into the bridge. Some suggestions for the design and application of slab mat are provided in the end of the paper.     

Application of the conditional source-term estimation model for turbulence–chemistry interactions in a premixed flame

Conditional Source-term Estimation (CSE) is a closure model for turbulence–chemistry interactions. This model uses the first-order CMC hypothesis to close the chemical reaction source terms. The conditional scalar field is estimated by solving an integral equation using inverse methods. It was originally developed and has been used extensively in non-premixed combustion. This work is the first application of this combustion model for a premixed flame. CSE is coupled with a Trajectory Generated Low-Dimensional Manifold (TGLDM) model for chemistry. The CSE-TGLDM combustion model is used in a RANS code to simulate a turbulent premixed Bunsen burner. Along with this combustion model, a similar model which relies on the flamelet assumption is also used for comparison. The results of these two approaches in the prediction of the velocity field, temperature and species mass fractions are compared together. Although the flamelet model is less computationally expensive, the CSE combustion model is more general and does not have the limiting assumption underlying the flamelet model.     

A dual model strategy to transfer multivariate calibration models for near-infrared spectral analysis

A dual-model method is proposed for correcting the calibration model. In the method, a primary calibration model is built using the spectra of a primary instrument and a correction model is established to describe the ratios between the predicted results from the spectra of different instruments. The prediction for the spectra of secondary instrument can be achieved by correcting the prediction of the primary model. A mathematical proof is described for the existence of the correction model, and the model is investigated using a near-infrared spectroscopic dataset of plant leaf samples measured on two instruments. The results show that a precise correction model is obtained and the model can be used to correct the predictions of the primary model. The correlation coefficients between the predicted and the reference ratios are above 0.9, and the prediction error after the correction is at the same level of the primary model.     

Ta及Nanbu库仑碰撞模型数值对比研究

深入研究库仑碰撞,对两种库仑碰撞模型-Ta模型与Nanbu模型在理论上进行了对比分析,详细阐述了两种模型中散射角大小的区别.在已有的采用Ta模型的全三维粒子模拟/蒙特长罗(PIC/MCC)算法基础上,采用Nanbu模型对电子间库仑碰撞计算模块重新进行了算法设计.分别应用Ta模型、Nanbu模型和无库仑碰撞的全三维PIC/MCC算法对国外热门负氢离子源JAEA 10A中的电子能量沉积进行了模拟分析.模拟结果与实验结果的对比分析发现:1)库仑碰撞使电子能量分布更接近于麦克斯韦分布;2)相对于传统的Ta模型,Nanbu模型的散射角考虑了多体碰撞的累加效果从而具有更高的期望值,按其模拟得到的电子温度具有更高的精度.这些为国内外学者设计相关算法指明了方向.     

Automatic fringe analysis of the induced anisotropy of bent optical fibres

A new theoretical model considering the refraction of the incident light beam by the fibre is suggested to determine the refractive index profile of bent optical fibres. This new model (slabs model) considering the cross section of the bent optical fibre consists of large number of slabs. The slabs model bases on the refraction of the incident beam by the fibre. The refractive index profile of the optical fibre cladding before bending obtained using the automated Fizeau interferometer with the aid of suggested model is compared with other models such as, the homogenous model and the multilayer model to verify the ability of this slab model. The refractive index profile of the bent optical fibre cladding is investigated using this suggested model. In addition, the new model is used to obtain the induced birefringence and the guiding parameters. The bending radius is recommended to be greater than 7.1 mm for the used optical fibre. The consideration of the refraction increases the accuracy of the results.     

用视密度加权平均二阶矩模型模拟旋流两相流动

本文用视密度加权平均代替时平均,建立了视密度加权平均的统一二阶矩两相湍流模型方程组（ＭＵＳＭ）,其中用体积分数代替了数密度,用颗粒驰豫时间作为封闭两相脉动速度关联方程耗散项的时间尺度,并引入了颗粒视在的气体速度脉动的输运方程。用ＭＵＳＭ模型模拟了旋流数为０．４７的气粒两相流动。并和实验结果及时间平均的ＵＳＭ模型的模拟结果进行了对照,两种模型均能较好地预报的两相的轴向和切向速度,轴向和切向脉动速度。此外,ＭＵＳＭ模型可以减少所用方程数,节省计算量。因此视密度加权平均的统一二阶矩两相湍流模型是一种对时间平均的统一二阶矩模型的改进,今后可以进一步扩大应用。     

THE INDENPENDENT α PARTICLE MODEL OF LIGHT NUCLEI

An α particle model of light nuclei is proposed. The physical picture of the model is clear, its wave functions are simpler and convenient for some applications. When it is used in the problems of multiple scattering, each term in the series of the multiple scattering expansion can be integrated out analytically. The experiments of elastic electron scattering can be well fited by using the model wave functions. The investigations of the model indicate that the usual rigid a particle model is the classical homologue of our model.     

包含液相扩散方程简化的锂离子电池电化学模型

锂离子电池的电化学模型对于电池特性分析和电池管理具有重要意义,但是准二维(P2D)模型复杂度太高,为了在保证模型精度的基础上尽量降低复杂度,本文提出了一种包含液相简化的P2D (LSP2D)模型,该模型首先基于电化学平均动力学将电池端电压化简成为仅耦合固相Li+浓度c_s和液相Li+浓度c_e的方程,然后进一步对表达c_s和c_e演化规律的偏微分方程进行抛物线近似化简,使得最终的模型由多项式组成.COMSOL仿真表明在放电倍率为1C时该模型与单粒子(SP)模型的估算精度和速度相当,但在放电倍率为3C时,该模型的估算时间比P2D模型减少了99.73%,与SP模型相当,估算精度相比SP模型有大幅度提升.     

非对称黏性空气动力学声带模型及其病理喉声源分类

二质量块模型(SH模型)在模拟病理发声时未考虑弹性力对发声系统的影响,也未考虑黏性气流在声门闭合阶段的作用,本文提出一种非对称黏性空气动力学声带模型(ISAC模型)。对非对称振动时的附加弹性系数和弹性形变进行分析,修正质量块所受的碰撞力,随位移量变化调节原始模型中的劲度系数,模拟环甲肌和甲杓肌的张力作用;通过声门倾角变化得到声门处的气流分布,以实现声带壁上的非对称气流压力作用。该模型应用于发声病理诊断,模型仿真和病理喉声源分类识别的实验结果显示,各声门特征参数相对误差不超过1.5%,ISAC模型的加权平均误差低于SH模型,二分类识别率和细分准确率均高于SH模型。      

入耳式耳机腔体结构的模型与优化

耳机的频响是由单元和腔体结构共同决定的。现有的耳机腔体结构仿真多采用集总参数模型,这类模型在高频段存在缺陷。该文在入耳式耳机的腔体结构仿真中引入基于传输线理论的声学模型,与传统模型相比,考虑损耗的传输线模型可提高入耳式耳机5 kHz～10 kHz频响仿真的准确性。在此基础上,优化算法提出改善耳机中高频频响的出声管设计方法。