连铸小方坯的组织与性能研究

The hot cracking of the continuous casting bullit is connected with its macrostructure and mechanical property burnt. The macrostructure and the mechanical property of 0. 13 wt- %C continuous casting bullit was investigated. The results are as follows: 1) the classical representation of the casting bullit shows three distinct zones, a peripherial region of small equiaxed grains, a columnar zone, and a central equiaxed zone. The rapid increase of the under cooling layer thickness is the criterion of the transformation from the columnar zone to central equiaxed zone; 2) The hardness decreases with the reducing of the solidification speed; 3) The tensile strength decreases gradually from the peripherial equiaxed maximum principal strain zone to central equiaxed zone ,and increases with the drop of the temperature.     

Deposition of boron nitride on graphite at 1300 K

A method for the deposition of BN onto graphite and other substrates is described. Boron trichloride (BCl₃) and ammonia (NH₃) diluted with Ar were used as reacting gases. The deposition process was carried out at 1300 K as well as lower temperatures in an open system at pressures of 1 atm. The consequences of the introduction of hydrogen to the system were considered. It was demonstrated that the replacement of argon with hydrogen increases the efficiency of the process as well as the theoretical rate of BN deposition. However, the acceleration of the deposition seems to be unprofitable, because the resulting supersaturation leads to the formation of an amorphous phase. The modification of the experimental conditions were proposed.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

代谢综合征的流行病学调查与分析

目的：了解20岁以上成年人代谢综合征的发生率；对比分析其相关的危险因素及保护因素。方法：(1)通过1026名20岁以上成人体检，应用修订的代谢综合征的美国诊断标准，凡具备以下5项标准中3项及3项以上，即①体质指数(BMI)≥24，②甘油三酯ρ(TG)≥150mg／dL，③高密度脂蛋白胆固醇ρ(HDL—C)男＜40mg／dL、ρ(HDL—C)女＜50mg／dL，④空腹血糖ρ(FBC)≥110mg／dL，⑤收缩期血压(SBP)≥130mmHg或舒张期血压(DBP)≥85mmHg或SBP／DBP≥130mmHg／85mmHg(1mmHg＝0．133kPa)，诊断为代谢综合征，共检出136名为病例组。(2)从既往无高血压、糖尿病、冠心病及血脂异常史，且本次筛检未纳入代谢综合征的人群中，抽取与病例组性别、年龄相当的136名进行配对调查分析，计算其相关因素的χ^2值、P值、机会比(OR)值，以及机会比值的95％可信限(OR 95％CI)。结果：(1)从1026名中共检出代谢综合征136名，其发生率为13．26％；(2)调查分析发现摄入过量和长时间处于坐位而又缺乏运动两项可能为代谢综合征的危险因素；而运动可能是代谢综合征的保护因素。结论：(1)本次广东地区部分人群筛查20岁以上成人代谢综合征的发生率为13．26％，虽较美国人为低，但中年组为17．48％，老年组高达29．27％，必须引起重视；(2)坚持终身运动和合理膳食可能是预防代谢综合征的切实可行、经济、有效的措施。     

一个数学建模问题的简单解法

银行利率给出了一个简单计算方法 ,这种方法更符合中学生思维的习惯 .     

动态随机弹性在期权定价中的应用

给出动态随机弹性的概念及运算性质,讨论了动态随机弹性在期权定价模型中的应用.主要结果有:(1)在波动率为常数时,期权价格对的弹性,得到了动态随机弹性服从运动,并给出了相应的经济解释;(2)由于波动率一般不是常数,也是随机过程,因此本文进一步研究了期权价格对波动率的弹性,就股票价格的波动情况给出了数学描述和金融意义上的解释.     

Mathematical analysis of investment systems

Investment systems are studied using a framework that emphasize their profiles (the cumulative probability distribution on all the possible percentage gains of trades) and their log return functions (the expected average return per trade in logarithmic scale as a function of the investment size in terms of the percentage of the available capital). The efficiency index for an investment system, defined as the maximum of the log return function, is proposed as a measure to compare investment systems for their intrinsic merit. This efficiency index can be viewed as a generalization of Shannon's information rate for a communication channel. Applications are illustrated.     

Research on Hawking Radiation as Tunneling from Schwarzshild-anti-de Sitter Black Hole

After taking into account energy conservation and the particle’s self-gravitation interaction, Hawking radiation of the massive particle as tunneling from Schwarzshild-anti-de Sitter black hole is studied by using Parikh-Wilczek’s semi-classical quantum tunneling approach. Meanwhile, Hawking radiation as tunneling from the black hole is reexamined by developing Angheben–Nadalini–Vanzo–Zerbini (ANVZ) covariant method to cover energy conservation and the particle’s self-gravitation interaction. Both the results perfectly generalize those obtained by Parikh and Wilczek, and show that the tunneling rate is related to the change of Bekenstein-Hawking entropy, and the factual emission spectrum is not exactly thermal, but satisfies the underlying unitary theory. PACS: 04.70-s, 9760. Lf.     

On the blow-up rate of large solutions for a porous media logistic equation on radial domain

In this paper we establish the exact blow-up rate of the large solutions of a porous media logistic equation. We consider the carrying capacity function with a general decay rate at the boundary instead of the usual cases when it can be approximated by a distant function. Obtaining the accurate blow-up rate allows us to establish the uniqueness result. Our result covers all previous results on the ball domain and can be further adapted in a more general domain.     

Lp[0,1]空间Müntz有理逼近的Jackson型估计

设Λ={λn}n∞=1为正的实数数列,且当n→∞时,有λn↘0.本文给出了当λn≤Mn-1/2,n=1,2,…,(其中M＞0为一正常数)时Müntz系统{xλn}的有理函数在Lp[0,1]空间的逼近速度,主要结论为Rn(f,Λ) Lp≤CMω(f,n-1/2)Lp,1≤p≤∞.     

多气隙电阻板室抗辐照性能研究

给出了为RHIC-STAR飞行时间探测器设计的多气隙电阻板室(MRPC)的辐照实验结果. 实验采用100mCi⁶⁰Co γ源, 采用不同的剂量率对MRPC进行辐照. 一个室在大剂量率2.87×10^－2Gy/h下辐照了24h后, 其性能如噪声计数率, 暗电流等均大大退化. 另一个室在相对低剂量率5.31×10^－4Gy/h下辐照了530h, 其性能没有见到任何变坏. 实验的目的是为了了解这种探测器在几年的运行中经过大剂量的辐照后的性能变化情况.