Noise-induced transitions in a double-well potential at low friction

A new integral representation of the transition rate holds for any friction and is shown to allow a feasible evaluation in a wide friction range. Analytic approximations include the (high-friction) Kramers result with the leading correction, as well as a low-friction case. The method is complementary to a recent one of Melnikov and Meshkov.     

低对比度非均匀干涉条纹图预处理研究

干涉条纹的预处理是干涉检测技术的重要步骤 ,但低对比度、非均匀干涉条纹图的处理是比较困难的。采用分区直方图调整法 ,根据条纹图的实际情况设置分区大小 ,并进行直方图调整 ,然后经过二值化、平滑、细化、整形等处理 ,得到单像素条纹图 ,为后续的条纹定位和物理量反演打下良好基础。实验证明该方法可以得到十分满意的结果     

Non‐Conformity with Faraday Law by Magnetoelectrolysis with Aluminum Electrodes

The present paper presents a study on the anode dissolution and corrosion of aluminum electrodes by electrolysis of aqueous solutions of sodium chloride in a magnetic field. The electrolysis was carried out under a galvanostatic regime with direct current and a uniform electric field. The magnetic field was generated by permanent magnets placed along the axis between an anode and cathode. The parameter current efficiency was used as a measure of the non‐conformity with the generalized Faraday law observed.     

在低价氮离子中实现3s-2p软X射线的最佳条件研究

从实现离子的基态和激发态之间粒子数反转的主要参量入手，数值计算了基态的 粒子数密度、上能级和下能级的统计权重之比、三体复合速率和自发辐射衰减速率之比等每个参量对反转粒子数密度的影响，并且以基于光场感生电离（OFI）复合机制B－likeN系统为例对实际系统进行分析讨论，给出了实现基于光场感生电离B-like N45.21nm3s-2p跃迁激光放大的最大激光功率密度。     

利用帧积分法去除微光图像噪声研究

在微光成像中，迭加在图像上的时空域噪声，不仅限制了系统可工作的最低照度，而且使显示图像具有随机蠕动颗粒闪烁的外观。图像处理技术能够提高图像质量，增强微光成像系统作用距离。实验证明，帧积分法对光子噪声以及系统内部信息载流子产生与复合所引起的散粒噪声的抑制有十分有效的作用。     

低温煤焦油常渣C5沥青质的分离与表征

从低温煤焦油中蒸馏提取出大于350℃的常渣,以正戊烷、正戊烷+5%乙醇、正戊烷+5%异丙醇三种溶剂沉淀沥青质。通过1H-NMR、13C-NMR、傅里叶变换离子回旋共振质谱仪(FT-ICR MS)、元素分析和相对分子量测定等手段对重组分沥青质的结构参数、杂原子化合物的分布等方面进行了分析,构建含杂原子的平均分子结构模型。结果表明,乙醇和异丙醇的加入可以显著降低C5-沥青质的收率,所得沥青质的芳香性增强,平均分子量增大,为更高缩合度的具有较短侧链的结构;极性溶剂的加入没有改变沥青质中杂原子化合物的类型,但是O1和O2中一部分低缩合度的化合物转移到可溶质中,O3-O6化合物的相对丰度增大,表明混合溶剂有利于萃取低缩合度的化合物。     

基于局部线性变换的色阶映射算法

为了提高高动态图像显示的视觉效果,提出了一种基于局部线性变换的色阶映射算法。针对图像直接线性压缩能力较差的缺点,本文提出一种局部的线性变换模型。由于局部窗的结构,是利用局部窗的中心像素点与窗内的其他像素点的均值,方差的关系构造而成,因此基于局部线性变换的色阶映射算法能够抑制由具有高对比度的图像边缘所引起的鬼影和光晕现象。首先,根据线性变换将图像的色阶映射转换为求解泛函的最优解;其次,通过推导求解出线性变换的参数并将泛函最优化问题转换为求解一个线性方程组问题;最后求解线性方程组,得出视觉效果较好的低动态范围图像。有效避免传统色阶映射出现的光晕和亮度不连续的现象,能够更多的保留高动态图像的细节。最后通过实验结果对比分析,通过信息熵和对比度两个参数可以体现文中算法较好。     

The possibility of the decomposition of 2'-deoxyribose moiety of thymidine induced by the low energy electron attachment

To evaluate the possibility of the decomposition of 2-deoxyribose moiety of thymidine induced by low energy electrons (LEE) attachment, the transition states and the energy barriers of the bond breaking processes of the ribose of the nucleoside have been studied theoretically by applying the density functional theory with the double zeta basis sets (DZP++). The energy barriers for the breakage of the C-C bonds (C(1')-C(2'), C(2')-C(3'), C(3')-C(4'), and C(4')-C(5')) of the ribose group of the radical anion of thymidine are found to be high (ca. 42-57 kcal/mol). The total energies of the C-C bond-broken products are significantly higher than that of the radical anion dT(*-). The decomposition of dT(*-) through the C-C bond rupture is unlikely to take place. The rupture of the C(1')-O(4') bond of dT(*-) needs an activation energy as low as 10.4 kcal/mol. However, the reversed reaction (C(1')-O(4') bond formation) needs the activation energy low as 0.3 kcal/mol. Therefore, the intermediate product LM1(C1')-(O4') is unlikely to be stable and the C(1')-O(4') bond-broken is not favored. The activation energy of the C(4')-O(4') bond rupture process amounts to 20.5 kcal/mol. The total energy of the C(4')-O(4') bond broken product is about 6.5 kcal/mol lower than that of the reactant dT(*-). The subsequent N1-glycosidic bond breaking process is found to have a very low energy barrier. Therefore, the LEE-induced base release through the C(4')-O(4') bond rupture might be a possible pathway.     

MnOx-SnO2 Catalysts Synthesized by a Redox Coprecipitation Method for Selective Catalytic Reduction of NO by NH3

MnO_x-SnO₂ composite oxides prepared by a redox coprecipitation route were tested in selective catalytic reduction of NO by NH₃ at low temperatures. The results showed that the MnO_x-SnO₂ catalyst with a Mn/(Mn+Sn) molar ratio of 75% exhibited the best performance, on which NO conversion of 100% could be achieved at temperatures of 120–200 °C. The characterization results of N₂ adsorption-desorption, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that the higher surface area, the formation of solid solution between manganese and tin oxides, and the high oxidation state manganese species were responsible for the high catalytic activity of the MnO_x-SnO₂ catalyst.