中国1:100万地貌图衡阳(G-49)幅简析——1.地貌结构特征及其发育过程

中国1:100万地貌图衡阳(G—49)幅,具有“+”字形过渡性的地貌格局,图幅范围内“丹霞地貌”和“喀斯特地貌”很发育,地貌类型多样,以流水地貌为主。在地质构造和地壳运动影响下,断裂发育,特别是新构造运动及外力因素,对区域地貌的形成,起着很大的作用。     

Hot compressive deformation behaviors of Mg–10Gd–3Y–0.5Zr alloy

In this paper, the hot compressive deformation characteristics of a Mg–10Gd–3Y–0.5Zr(GW103K) alloy have been investigated by isothermal compression test at the temperature range of 350–450°C and strain rate range of 0.0001–0.1s~(-1). True stress–strain relationships at various strain rates showed the typical strain hardening and softening stage which is indicative of dynamic recrystallization during deformation. The results showed that the peak stress was obviously dependent on temperature and strain rate. A constitutive equation to describe the deformation process was established based on the hyperbolic sine function. The stress exponent n and apparent activation energy Q were determined to be 3.018 and 203.947 k J/mol, respectively. Microstructure investigation showed that dislocation slipping was the dominant deformation mechanism during the hot deformation at all conditions. However, at the temperatures lower than 400 °C and strain rates higher than 0.01 s~(-1), twinning was observed to be activated, which indicated another deformation mechanism. Dynamic recrystallization and dynamic precipitation were found to occur simultaneously under such deformation condition.     

长江流域的环境灾害与经济发照

长江流域是我国重要的自然资源聚集区和经济增长带。近几十年来,长江流域的环境灾害经常发生,其原因一方面与森林锐减有关,另一方面与工业发展有关。为了在长江流域保持可持续发展,必须在转变观念、控制人口、完善机构、保护森林、普法执法等方面加强工作。     

圆柱活齿传动的强度计算

在圆柱活齿传动受力分析的基础上．利用微分几何、弹性力学和优化设计的方法推导出这种传动的强度计算公式．这些公式可供设计计算时参考．     

基于支持向量机的混沌时间序列非线性预测

提出一种新的应用支持向量机回归原理的混沌时间序列非线性预测方法,同时利用自适应的方法对支持向量机的参数进行优化.仿真结果显示支持向量机具有比传统的回归方法更好的泛化能力,预测方法具有很高的预测精度,同时还讨论了支持向量机中参数以及嵌入维数的变化对泛化误差的影响,得出的结论与统计学习理论中的VC维理论相一致.     

兼顾连笔和笔顺的联机手写汉字识别方法

为解决联机手写汉字识别技术中兼顾连笔和笔顺的难题，提出了联机手写汉字的模糊属性关系图描述和基于知识的松驰匹配方法。该方法能充分描述汉字结构、对手写变形不敏感，并具有良好的连笔字识别能力和适应不同笔顺的特点。基于上述方法，作者实现了一个联机手写汉字识别系统。实验结果表明，本方法能够有效地增加对于低限制书写汉字的识别正确率，并具有较好的抗噪声能力。经过２２５３０汉字测试，首位识别率达９８．８％，前十位识别率达９９．７％。     

Synthesis,characterization, and theoretical study of N,S-codoped nano-TiO<Subscript>2</Subscript> with photocatalytic activities

Nitrogen and sulfur doped titanium dioxide photocatalysts were prepared by the sol-gel method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra (DRS). Photocatalytic activities of the samples were investigated on the degradation of methyl orange (MO). The effect of the dopants on the electronic structure of TiO₂ was studied by the first-principles calculations based on the density functional theory (DFT). The orbital hybridization resulted in energy gap narrowing and electronic delocalization in the crystal of doped TiO₂. Mobile electrons of varied energetic states could offer enhanced electron transfer, together with optical absorption improvement. The results show that the doping elements of N and S play a cooperative role in the modification of electronic structure, which enhances the photocatalytic performance. The experimentally observed absorption edges of N-doped TiO₂, S-doped TiO₂, and N, S-codoped TiO₂ are 420, 413, and 429 nm, respectively, which can be explained by the theoretical calculation results.     

纳米TiO2光降解触媒丝的制备

以草酸氧钛酸为前驱物,采用"浸渍-提拉法"在玻璃纤维丝基体上生成纳米TiO2前驱物薄膜,经过热分解得到纳米TiO2光降解触媒丝.XRD分析表明触媒丝表面薄膜为锐钛矿型TiO2, SEM形貌分析表明有部分小颗粒TiO2团聚在薄膜表面,颗粒粒度≤100 nm.该纳米TiO2光降解触媒丝能够在1 h内使罗丹明B在紫外光作用下降解66.67%～72.22%.     

WO_3-Fe_2O_3异质结的制备及光催化活性

利用新型燃烧法和水热法分别制得α-Fe2O3及六方晶系无水WO3,再用溶剂分散法制得WO3-Fe2O3异质结.采用XRD,TEM,BET比表面积、紫外-可见漫反射谱 (DRS) 等技术对WO3-Fe2O3进行了表征,并以罗丹明B的光催化降解为探针反应, 评价了其光催化活性.结果表明,复合氧化物WO3-Fe2O3的粒子形态均为棒状,粒径约为80 nm,比表面积为46.91 m2/g;在可见光区有强吸收, 带隙估算为2.4 eV;对多种染料具有光催化降解活性,其中0.1 g WO3-Fe2O3(ω(Fe2O3 )=5%)在可见光作用下,100 mL 10 mg/L的罗丹明B降解率可达到97.73%, 表现出明显的可见光降解活性.通过计算半导体能带位置,讨论了光催化反应活性提高的机理.     

多元羟乙氧基苯的合成

以多元酚为原料，乙醇做溶剂，在相转移催化剂条件下与氯乙醇作用，合成多元羟乙氧基苯的方法，提高了产品产率，缩短了反应时间。