Directed flow of lambda hyperons in (2-6 )A GeV Au+Au collisions

Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.     

近红外光谱法预测粗皮桉木材气干密度的影响因素分析

采用近红外光谱分析技术,对粗皮桉木材气干密度校正模型的影响因素进行比较研究.使用直接测量法测量了粗皮桉木材的气干密度,并用近红外光谱仪采集试样的近红外漫反射光谱,对不同切面、厚度、含水率和粗糙度的粗皮桉木材试样的原始光谱进行二阶导数预处理并选择一定光谱段建立回归模型.以50～140个试样作为校正集建立木材气干密度的偏最...     

Wideband high-efficient linear polarization rotators

We demonstrate a wideband polarization rotator with characteristics of high efficiency and large-range incidence angle by using a very simple anisotropic reflective metasurface. The calculated results show that reflection coefficient of cross polarization is larger than 71% over an octave frequency bandwidth from ~4.9 GHz to ~10.4 GHz. The proposed metasurface can still work very well even at incidence angle of 60?. The experiment at microwave frequencies is carried out and its results agree well with the simulated ones.     

Characterization of Cr‐doped Sb2Te3 films and their application to phase‐change memory

Phase‐change memory (PCM) is regarded as one of the most promising candidates for the next‐generation nonvolatile memory. Its storage medium, phase‐change material, has attracted continuous exploration. Along the traditional GeTe–Sb₂Te₃ tie line, the binary compound Sb₂Te₃ is a high‐speed phase‐change material matrix. However, the low crystallization temperature prevents its practical application in PCM. Here, Cr is doped into Sb₂Te₃, called Cr–Sb₂Te₃ (CST), to improve the thermal stability. We find that, with increase of the Cr concentration, grains are obviously refined. However, all the CST films exhibit a single hexagonal phase as Sb₂Te₃ without phase separation. Also, the Cr helps to inhibit oxidation of Sb atoms. For the selected film CST_10.5, the resistance ratio between amorphous and crystalline states is more than two orders of magnitude; the temperature for 10‐year data retention is 120.8 °C, which indicates better thermal stability than GST and pure Sb₂Te₃. PCM cells based on CST_10.5 present small threshold current/voltage (4 μA/0.67 V). In addition, the cell can be operated by a low SET/RESET voltage pulse (1.1 V/2.4 V) with 50 ns width. Thus, Cr–Sb₂Te₃ with suitable composition is a promising novel phase‐change material used for PCM with high speed and good thermal stability performances. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

交通装备售后绩效保障系统控制策略研究

针对装备售后保障逐渐向绩效保障模式转变的趋势,文章研究绩效模式下的交通装备售后保障系统控制策略,分析部件损耗特征并给出不同模拟情境下的最优控制策略;首先,从仓库备件库存出发推导出备件库存水平状态概率分布,并获得如可用度等系统绩效性能指标,然后,建立绩效约束的保障系统优化模型并设计出有效的遗传算法;最后,进行数值实验;结果表明,平均故障间隔时间对保障系统控制策略的影响大,而备件可修复率对保障系统控制策略的影响较小。     

短寿命核转轮传送装置

在中国原子能科学研究院的串列式静电加速器上建立了传送短寿命核的转轮装置,可用于鉴别和研究寿命短至几秒的核素．该装置已用于新的缺中子核素９０Ｒｕ的鉴别及其半衰期和衰变γ的测量． A wheel device for transporting short-lived nuclei has been constructed at the HI-13 tandem accelerator of CIAE. The device can be used in the identification and investigation of nuclides with life-times as short as a few seconds. With the aid of this device a new nutron-deficient nuclide 90Ru has been identified. Its half-life and decay γ-rays have been measured.     

热压制备(AgSbTe2)100-x-(GeTe)x合金的热电性能

以Pb粉、Te粉、Ag粉、Ge粉为原材料,在真空气氛下合成(AgSbTe₂)_100-x-(GeTe)_x (x=80---90) (TAGS)合金热电材料, X射线衍射(XRD)分析表明,热压烧结后合金具有低温菱形结构. 通过热压烧结法将TAGS粉末制备成块体材料,运用XRD和扫描电子显微镜对材料的物相成分、 晶体结构和形貌进行了表征.采用直流四探针法测定样品的电导率,当样品两端的温差为1---4℃ 的情况下测量Seebeck系数.通过材料热电性能测试,研究了30---500℃温度范围内不同组分 样品性能参数的变化.结果表明,所制备的TAGS热电材料具有纳米结构, 其性能随着组分的变化而变化, TAGS-80具有较好的热电性能,在530℃时具有最高热电优值(ZT=1.80).     

碳纤维复合材料内部缺陷深度的定量红外检测

利用脉冲红外热成像技术对碳纤维复合材料试件内部的模拟脱黏缺陷的深度进行测量, 研究在被测物热属性参数未知情况下,碳纤维增强塑料中缺陷深度的测量方法. 分析了平板材料在脉冲热源激励下的一维热传导模型;给出了内部缺陷深度的红外测量原理; 选用对数温度二阶微分峰值时刻作为特征时间测量缺陷深度; 考虑单点标定测量深度可能产生较大的随机误差,提出利用最小二乘法多项式拟合建立阶梯件中阶梯深度与其对应的对数温度时间二阶微分曲线峰值时间两者之间的标定关系式的方法, 选择在相对误差平方和最小情形下的拟合关系式作为脱黏缺陷深度测量的标定关系式. 实验结果表明,利用该方法测量脱黏缺陷深度的精度优于单点法标定测量结果, 实现了在被检测材料热属性参数未知的情况下仍能较准确地测量脱黏缺陷深度.     

A wide dynamic range laser rangefinder with cm-level resolution based on AGC amplifier structure

A pulsed time-of-flight (TOF) laser rangefinder with a pulsed laser diode and an avalanche photo diode (APD) receiver is constructed and tested. Trigged by an avalanche transistor, the laser diode can emit a periodic pulse with rise time of ～2 ns. A new structure with auto gain control (AGC) circuits both in the pre-amplifier and the post-amplifier is presented. Through this technology, not only the dynamic range of the receiver is extended, but also the walk error of timing discriminators is reduced. Large measurement range from 5 m to 500 m is achieved without any cooperative target. The single-shot precision is 3 cm for the weakest signal. Compared with previous laser rangefinders, the complexity of this system is greatly simplified.