单标记方法在ψ(3686)重子对衰变中的应用研究

基于BOSS软件框架,利用5.06×10~8ψ(3686)蒙特卡罗样本,对单标记方法与遍举方法在ψ(3686)重子对衰变测量中的应用开展了研究.结果表明在未考虑次级衰变分支比的情况下单标记方法探测效率达到了34.35%,而遍举方法探测效率仅有3.79%.通过对比两种方法得到的探测效率、信噪比、信号事例数等,我们发现单标记方法在粲偶素衰变到重子对末态的测量中具有更大的优势.

基于液压力矩对非圆齿轮马达配流规律的研究

在研究非圆齿轮液压马达各容腔液压力矩的存在状态及作用规律的基础上,采用分析各容腔力矩存在状态的方法,结合配油盘的设计理论,对马达的配流规律进行研究,得到马达的具体配流规律。使得对配流盘的分析及配流规律的研究有理有据且结果更加直观,为非圆齿轮液压马达的研究提供理论支持。

汽车空气弹簧特性分析

利用CATIA软件创建空气弹簧的结构模型,分析普通路面对汽车平顺性的影响,用MATLAB软件编程对空气弹簧进行数据分析,分析空气弹簧运动过程中的动力学特性,文中主要研究汽车膜式弹簧的刚度特性、频率特性等在空气弹簧瞬间跳动过程有什么变化,根据特性变化分析空气弹簧的设计理念。

一种新型椭圆齿轮马达的动力学分析

为了增大非圆齿轮马达的排量,平衡马达的径向力,提出了6-8阶低速大扭矩椭圆齿轮马达。从椭圆齿轮的传动特性出发,得到了该椭圆齿轮系统的建模过程,绘制出了该非圆行星齿轮系统中各个齿轮的节曲线以及齿廓图形。在分析各个激振参数,并考虑了行星齿轮系统中各啮合齿轮的时变啮和刚度,啮合相位及齿轮副间隙的基础上,建立了椭圆行星齿轮系统的的动力学方程,并得出了系统的动态响应。动力学模型建立与求解的方法对于一般的非圆行星齿轮系统的动力学分析具有普遍适用的意义。

谒方汉英陵园

献宇陵园幻彩光，浓荫荟萃百花香。豪雄殉国捐躯后，芳骨英魂民尽张。

Evidence for the decays of ∧_c^+→∑^+η and ∑^+η’

We study the hadronic decays of ∧c^+ to the final states ∑^+η and ∑^+η, using an e^+e^- annihilation data sample of 567 pb^-1 taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCII collider. We find evidence for the decays ∧^+→∑^+η and ∑^+η' and with statistical significance of and , respectively. Normalizing to the reference decays ∧^+→∑^+π^0 and ∑^+ω, we obtain the ratios of the branching fractions B(∧C^+→∑^+η)/V(∧^→∑^+π^0)and B(∧C^+→∑^+η)/B(∧C^+→∑^+ω)to be and , respectively. The upper limits at the 90% confidence level are set to be B(∧C^→∑^+η)/V(∧^+→∑^+π^0)<0.58 and B(∧C^+→∑^+η)/B(∧C^+→∑^+ω)<1.2. Using BESIII measurements of the branching fractions of the reference decays, we determine B(∧C^+→∑^+η)=(0.41±019±0.05)%(<0.68%) and B(∧C^+→∑^+η)=(1.34+0.53+0.19)%(<1.9%). Here, the first uncertainties are statistical and the second systematic. The obtained branching fraction of ∧C^+→∑^+η is consistent with the previous measurement, and the branching fraction of ∧C^+→∑^+η is measured for the first time.

Measurement of e^+e^-→D■ cross sections at the ψ(3770) resonance

We report new measurements of the cross sections for the production of DD final states at theψ（3770）resonance.Our data sample consists of an integrated luminosity of 2.93 fb^（-1）of e~＋e^-annihilation data produced by the BEPCⅡ collider and collected and analyzed with the BESⅢ detector.We exclusively reconstruct three D^0and six D~＋hadronic decay modes and use the ratio of the yield of fully reconstructed DD events（“double tags”）to the yield of all reconstructed D or D mesons（“single tags”）to determine the number of D^0 D^0and D~＋D^-events,benefiting from the cancellation of many systematic uncertainties.Combining these yields with an independent determination of the integrated luminosity of the data sample,we find the cross sections to beσ（e~＋e^-→D^0D^0）=（3.615±0.010±0.038）nb andσ（e~＋e^-→D~＋D^-）=（2.830±0.011±0.026）nb,where the uncertainties are statistical and systematic,respectively.

Measurement of the integrated Luminosities of cross-section scan data samples around theψ(3770)mass region

To investigate the nature of the Ψ（3770） resonance and to measure the cross section for e^＋e^-→DD, a cross-section scan data sample, distributed among 41 center-of-mass energy points from 3.73 to 3.89 GeV, was taken with the BESIII detector operated at the BEPCII collider in the year 2010. By analyzing the large angle Bhabha scattering events, we measure the integrated luminosity of the data sample at each center-of-mass energy point. The total integrated luminosity of the data sample is 76.16±0.04±0.61 pb^-1, where the first uncertainty is statistical and the second systematic.