近垒及垒下能区28Si+174Yb体系的裂变碎片质量分布

使用两块大面积平行板雪崩计数器,测量了近垒及垒下28Si+174Yb熔合裂变碎片质量-角度关联分布及质量分布。质量-角度二维图显示在该反应能量区间内并没有发现明显的准裂变成分。运用单高斯曲线拟合了裂变碎片的质量分布并抽取了质量宽度。结果表明:在库仑势垒以上,质量宽度随着反应能量的升高而增大;在库仑势垒以下能区,发现质量宽度随着反应能量的降低而呈现轻微增大的趋势。运用鞍点统计模型对本次实验数据拟合发现,需用比文献给出的更大的刚度系数才能重现实验结果,其物理原因还需要进一步研究。In order to study the fission mechanism, the mass distributions and mass-angle distributions of the fission fragments for 28Si+174Yb were measured near the Coulomb barrier. The mass-angle correlations do not indicate any possible quasi-fission events in this bombarding energy range. The mass distributions were fitted by the single Gaussian distribution and then the mass widths were extracted. At above-barrier energies, the mass widths were found to increase with the energy. However, the mass widths show slight increase with decreasing energy below the barrier. Additionally, the mass widths can not be reproduced in the framework of the saddle statistic model with the given parameter, so further study is still needed.     

192Tl高自旋态能级结构研究

通过熔合蒸发反应181Ta（16O,5n）192Tl,在入射束流为97 MeV能量下,布居192Tl的高自旋态,更新了192Tl的能级纲图。共增加8条新能级,尝试性地指定了能级自旋,将负宇称晕带的能级推高到23-?。讨论了192Tl与相邻同位素奇奇核194,196,198Tl负宇称晕带的旋称劈裂与反转现象,发现随着中子数增加,196,198Tl在高自旋处出现了旋称反转,其原因可能是由于中子质子相互作用与科里奥利力相互竞争所致。High spin states of 192Tl were populated by the 181Ta(16O, 5n)192Tl heavy ion fusion evaporation reaction at 97 MeV beam energy. A new level scheme with 8 new levels was constructed and the level spins were tentatively assigned. The negative yrast band was extended up to 23-?. Systematics of signature of inversion were also discussed for the negative yrast band of odd-odd Tl istopes. Signature inversion has been found in 196,198Tl with neutron number increasing in these four Tl isotopes, and it is explained by the competition between the strength of n-p interaction and Coriolis force.     

Radiation effect of neutrons produced by D–D side reactions on a D–3He fusion reactor

One of the most important characteristics in D–³He fusion reactors is neutron production via D–D side reactions. The neutrons can activate structural material, degrading them and ultimately converting them into high-level radioactive waste, while it is really costly and difficult to remove them. The neutrons from a fusion reactor could also be used to make weapons-grade nuclear material, rendering such types of fusion reactors a serious proliferation hazard. A related problem is the presence of radioactive elements such as tritium in D–³He plasma, either as fuel for or as products of the nuclear reactions; substantial quantities of radioactive elements would not only pose a general health risk, but tritium in particular would also be another proliferation hazard. The problems of neutron radiation and radioactive element production are especially interconnected because both would result from the D–D side reaction. Therefore, the presentation approach for reducing neutrons via D–D nuclear side reactions in a D–³He fusion reactor is very important. For doing this research, energy losses and neutron power fraction in D–³He fusion reactors are investigated. Calculations show neutrons produced by the D–D nuclear side reaction could be reduced by changing to a more ³He-rich fuel mixture, but then the bremsstrahlung power loss fraction would increase in the D–³He fusion reactor.     

A new simple approach to predict entropy of fusion of nitroaromatic compounds

In this paper, a new model is introduced to predict entropy of fusion of nitroaromatic compounds, which can be used for some well-known high explosives such as 2,4,6-trinitrotoluene (TNT) and N-methyl-N,2,4,6-tetranitroaniline (TETRYL). Novel correlation contains two different functions for which elemental composition and symmetry of nitroaromatic compounds are used to present additive and non-additive contributions, respectively. The presence of some molecular fragments may influence the value of non-additive function. The root-mean-square (rms) deviation of predictions of entropy of fusion from 66 measured values (corresponding to 61 molecules) is 7.88 J/K mol. The predicted results are compared with one of the best available semi-empirical methods, which show the reliability of the new method is relatively good.     

An aggregation framework based on coherent lower previsions: Application to Zadeh’s paradox and sensor networks

The problem of aggregating two or more sources of information containing knowledge about a common domain is considered. We propose an aggregation framework for the case where the available information is modelled by coherent lower previsions, corresponding to convex sets of probability mass functions. The consistency between aggregated beliefs and sources of information is discussed. A closed formula, which specializes our rule to a particular class of models, is also derived. Two applications consisting in a possible explanation of Zadeh’s paradox and an algorithm for estimation fusion in sensor networks are finally reported.     

基于贝叶斯信息融合的岸桥有限元模型修正研究

为建立精确的岸桥有限元模型,研究了基于贝叶斯信息融合的模型修正方法．通过方差分析,确定待修正参数,利用中心复合试验设计获取样本点,根据有限元计算结果与实测的结果残差为目标函数获得响应样本．拟合样本点和响应样本值构建二阶多项式响应面模型,并检验响应面模型的精度．基于贝叶斯理论更新融合系数来优化响应面参数,从而获得修正模型．以宁波大榭3号岸桥为工程背景,对比修正后的模态频率和实测频率,最大频率相对误差不超过5%,进而验证了基于贝叶斯信息融合的动力学有限元模型修正方法的有效性．修正后的有限元模型可进一步应用于岸桥的健康监测和安全评估．     

Assessment of quality consistency in traditional Chinese medicine using multi‐wavelength fusion profiling by integrated quantitative fingerprint method: Niuhuang Jiedu pill as an example

Under the wave of the revival of traditional Chinese medicine, there is a quite imperative duty to study an integrated and comprehensive method of fingerprint data processing and analysis on the quality consistency of traditional Chinese medicine. So, we proposed six parameters from two aspects (qualitative and quantitative), three levels (biased to strong peaks, biased to weak peaks, no obvious bias), to comprehensively evaluate the similarity of the two fingerprints. On this basis, another five parameters were proposed to evaluate the integrated effects (consistency, volatility, and similarity). This method was applied to 22 batches of Niuhuang Jiedu pill samples. Next, a practical and convenient multi‐wavelength fusion method was designed to provide more information, and the generated fusion profilings were used for subsequent evaluation. The characteristics of the parameters were confirmed by correlation analysis. The results of both hierarchical clustering analysis and principal component analysis for raw data and standardized data were consistent with integrated quantitative fingerprint method results. At the same time, this method gave a reasonable explanation for abnormal and dissimilar samples. This work illustrated that the proposed method was particularly suitable for similarity analysis of fingerprints and capable of ensuring the quality consistency in traditional Chinese medicine.     

低信噪比条件下多节点声呐目标跟踪算法*

低信噪比条件下,单个主动或单个被动声呐节点难以实现目标跟踪。多节点声呐系统希望通过增加探测节点提高系统探测能力,但其性能提高与否取决于选择合适的数据融合算法。本文利用双节点声呐试验数据研究低信噪比条件下的目标跟踪方法,采用“结合置信度水平的表决融合”算法对多个探测节点得到的数据进行融合,既考虑了目标回波信号的信噪比特性,又考虑了目标运动的连续性特征,还考虑了各节点探测结果的决策优化,最终实现较高精度的目标跟踪。算法实现了数据级、特征级和决策级的统一、融合,通过对判决依据进行量化、分层,简化判决的复杂性。试验数据处理结果表明,该方法能较好地解决低信噪比条件下多节点声呐目标跟踪问题,目标跟踪精度较高。     

激光加载下金属锡材料微喷颗粒与低密度泡沫混合实验研究

金属材料的微喷是冲击加载下金属表面发生的一种动态破碎现象,微喷研究在很多领域都具有重要意义,包括惯性约束聚变(ICF)和烟火制造等.由于激光实验特有的优势,近几年国内外开展了很多利用强激光驱动冲击加载研究材料微喷过程的实验.利用泡沫材料对微喷颗粒进行静态软回收虽然可以获得颗粒的形态分布、颗粒尺寸及颗粒质量等定量结果,但并不能反演微喷颗粒从进入泡沫到停滞过程中的动态混合过程.为此,在神光Ⅱ升级装置上利用皮秒脉冲激光照射金丝产生高能X射线,实现了对锡微喷颗粒与低密度泡沫混合过程的高时间分辨和高空间分辨背光照相.背光图像面密度结果证实微喷颗粒在泡沫中并没有发生二次破碎.静态回收结果表明,在锡材料与泡沫紧贴放置的情况下,微喷颗粒在泡沫中的穿透深度随着加载压强升高呈现先增大后减小的规律,与非紧贴放置的实验结果有明显的差别.     

基于参数化模型的内冷屏设计优化流程的开发

在中国聚变工程实验堆(CFETR)集成设计平台(CIDP)的设计框架中,基于参数化模型开发了能够高效开展内冷屏设计优化的工作流程。通过OPTIMUS 软件驱动CATIA、ANSYS 等CAD/CAE 软件进行自动建模及有限元分析,利用响应面模型、敏感度分析等方法确定与优化目标关系密切的参数,该流程根据内冷屏的参数化模型的几何参数驱动优化流程得到满足设计判据的优化设计参数。在应用示例中,考虑到等离子体破裂工况下冷屏的安全运行要求,在电磁-结构分析得到的应力满足设计判据的前提下,通过优化几何参数使内冷屏的质量最小,从而降低建造成本、提高经济性。