Fe2O3与TiF3添加剂对LiBH4-MgH2复合氢化物体系的协同催化作用

通过球磨方法制备出2LiBH4-MgH2,2LiBH4-MgH2-10%Fe2O3,2LiBH4-MgH2-10%TiF3,2LiBH4-MgH2-5%Fe2O3-5%TiF3和2LiBH4-MgH2-10%Fe2O3-10%TiF35个复合氢化物体系,用热重(TG)、差示扫描量热(DSC)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和压力-组成-温度仪(PCT)等对所制备体系进行表征.结果表明,Fe2O3和TiF3的掺杂均能够有效地改善2LiBH4-MgH2复合体系的放氢性能,尤其是两者共掺杂的2LiBH4-MgH2-10%Fe2O3-10%TiF3体系,初始放氢温度为110℃,总放氢量达到约9.6%.对2LiBH4-MgH2-5%Fe2O3-5%TiF3体系的PCT表征结果表明,在400℃时,10 min内放氢量达到了8.6%,放氢热力学和放氢动力学均优于单一相的掺杂,体现了两相掺杂的协同催化作用.     

THE ASYMPTOTIC DISTRIBUTIONS OF EMPIRICAL LIKELIHOOD RATIO STATISTICS IN THE PRESENCE OF MEASUREMENT ERROR

Suppose that several different imperfect instruments and one perfect instrument are independently used to measure some characteristics of a population. Thus, measurements of two or more sets of samples with varying accuracies are obtained. Statistical inference should be based on the pooled samples. In this article, the authors also assumes that all the imperfect instruments are unbiased. They consider the problem of combining this information to make statistical tests for parameters more relevant. They define the empirical likelihood ratio functions and obtain their asymptotic distributions in the presence of measurement error.     

大型超静定回转窑支承载荷求解通用方法

回转窑是冶金、水泥、耐火材料连续生产中的关键设备，是一种重载、大扭矩、多支点、超静定运行系统。本文针对回转窑载荷分布和刚度变化复杂的特点，建立起支承载荷求解的通用力学模型和求解矩阵，分别推导出窑头、窑尾为悬臂端和简支支承时，支承载荷分配与轴线偏差的线性关系式，并给出应用实例。这对合理调整与维护回转窑，保证它安全、高效地运行，有效提高企业经济效益有重要意义。     

Digital discrimination of neutron and γ ray using an organic scintillation detector based on wavelet transform modulus maximum

A novel algorithm for the discrimination of neutron and γ -ray events with wavelet transform modulus maximum (WTMM) in an organic scintillation has been investigated. Voltage pulses arising from a BC501A organic liquid scintillation detector in a mixed radiation field have been recorded with a fast digital sampling oscilloscope. The WTMM method using frequency-domain features exhibits a strong insensitivity to noise and can be used to discriminate neutron and γ -ray events based on their different asymptotic decay trend between the positive modulus maximum curve and the negative modulus maximum curve in the scale-space plane. This technique has been verified by the corresponding mixed-field data assessed by the time-of-flight (TOF) method and the charge comparison (CC) method. It is shown that the characterization of neutron and γ ray achieved by the discrimination method based on WTMM is consistent with that afforded by the TOF method and better than the CC method. Moreover, the WTMM method itself has presented its ability to eliminate the noise without any pretreatment to the pulses.     

等离子体天线开启时间光电时差测量法

将发射光谱信号引入到辉光放电等离子体天线开启时间测量当中,根据等离子体光信号与激励电压信号的时间差测出辉光等离子体天线的开启时间。结果发现该方法可有效测量直流和频率较高的交流辉光等离子体天线开启时间。直流和kHz级交流等离子体天线开启时间约为在1 ms,MHz级交流等离子体天线开启时间在0.5 ms左右。而对于50 Hz低频交流等离子体天线,由于放电状态不稳定,测量误差较大。天线的开启时间与激励电源的功率和电源的响应时间有很大关系。在一定范围内,随放电功率增加,天线的开启时间缩短。同时放电功率的增加也增大了天线开启时间测量结果的可重复性,误差减小,为1%~2%。     

基于SSA–LSTM框架的花岗岩失稳破坏前兆细观组分分析

以花岗岩为例,使用阈值分割技术识别了岩石的细观组分,分析了单轴压缩条件下岩石破坏前兆的细观组分特征,使用麻雀搜索算法（sparrow search algorithm, SSA）对长短期记忆（long short-term memory, LSTM）进行了改进,基于改进的LSTM对岩石破坏细观组分前兆进行了预测。结果表明,裂隙面积第二次激增、石英或长石面积第二次陡降可作为岩石的破坏前兆;基于细观组分的岩石破坏前兆时间比肉眼观察到岩石破坏时间提前了约4 s;改进LSTM对岩石破坏石英前兆的预测能力最强,长石次之,对裂隙预测能力最差。

     

Al2O3-ZrO2-YAG复相粉末的低温合成研究

用低温原位合成技术制备了Al2O3-ZrO2-YAG复相粉末,在1100℃,5h热处理后,Al-Zr-Y-O体系中的主相为ZrO2四方相,其余为无定形相,表明ZrO2抑制了Al2O3和YAG晶粒的生长,同时Al2O3和YAG抑制了ZrO2从四方相向单斜相的转变.在1580℃,1h热处理后,Al-Zr-Y-O体系中的复相组成为(115+90x)Al2O3+54(Y2O3)x·ZrO2+(32-36x)YAG,其中0 ≤x＜0.88(mol).     

大口径掺钛蓝宝石晶体放大的实验研究

分析了口径为80 mm的钛宝石晶体内的增益特性,对大口径钛宝石晶体中的泵浦光能量密度和泵浦光口径进行了优化设计。对于80 mm×17 mm的晶体,最佳工作光束口径为55 mm,泵浦能量为50 J;对于80 mm×30 mm的晶体,最佳工作光束口径为60 mm,泵浦能量为90 J,且其横向小信号增益远小于80 mm×17 mm晶体的。对影响大口径钛宝石晶体放大的横向放大自发辐射（ASE）和寄生振荡采用折射率匹配的包边技术进行了抑制。实验表明,该方法把允许横向增益从13提高到了2 100。实验系统为100 J绿光台面泵浦激光器,100 TW主放大器采用四程空间构型放大光路。80 mm×17 mm钛宝石晶体c轴水平放置,泵浦光和主激光均为水平偏振。当以泵浦光能量为49 J对主放大器进行双端泵浦,注入信号光能量为1.2 J,光束口径60 mm时,获得了14.2 J的放大光输出和286 TW的最高峰值功率。     

P1波入射准饱和土的波型转换问题

针对各向同性准饱和土体中体波的传播问题,本文深入研究了P1波(第一纵波)入射土体时所出现的波型转换现象。在准饱和土波动方程的基础上,通过数值算例,找出标准参数土体模型的临界饱和度及波型转换角,并分析土体孔隙率、渗流系数、水压力和入射波频率等参数对该现象的影响。     

光学神经网络模式识别系统原理及其现状

评述光学神经网络模式识别系统的原理及发展现状并就几个比较典型的问题进行了讨论。