旋转对称非球面自动加工控制算法研究

介绍了计算机控制光学表面成型（ＣＣＯＳ） 技术的基本原理,对双旋转磨头的去除函数进行研究,研究了不同形状的磨头的去除函数特性,并在多次实验的基础上得到了最优的加工参数,在去除函数的基础上提出了模板函数的概念及算法。根据加工旋转对称非球面光学表面的特点,结合模板函数提出了一种基于同心圆磨头运动轨迹的控制算法。运用该算法对神光Ⅲ号打靶非球面透镜的一种工艺试样（ Φ３００ｍ ｍ ,Ｆ５－９ ,最大非球面度为４６μｍ） 进行自动加工,面型精度达到１λ（ＲＭＳ,λ＝ ６３２－８ｎｍ）,取得了满意的结果。     

Study of latent and etched tracks by a charged particle transmission technique

A recently suggested technique for non-destructive investigation of inhomogeneities in thin objects, which is based on the measurement of the energy spectra of charged particles transmitted through the object, is used for the study of thermal annealing of 10–20 μm thick polyethylene terephtalate, polypropylene and polycarbonate foils irradiated with 1–10 MeV/amu heavy ions. At elevated temperature a foil linear contraction is observed on pristine and irradiated material. Also the foil roughness increases with increasing temperature. On the same foils with etched pores 0.5–1.0 μm in diameter, the thermal annealing results in gradual closing of the pores up to about 30% of their initial diameter at the temperatures of 150–175°C. At higher temperatures the pore diameter increases and achieves its initial value.     

Comparison of Makrofol-E and CR-39 as Solid State Nuclear Track Detectors

A comparison of the etching parameters as well as the neutron response for Makrofol-E and CR-39 was considered as solid state nuclear track detectors. The calculated sensitivity for both detectors was compared with the measured one. It is found that CR-39 has higher response to fast neutrons than Makrofol-E. The response increase due to decreasing the rate of layer removed and increasing the etch-pits per unit area.     

Lichens as biomonitors for the determination of polycyclic aromatic hydrocarbons (PAHs) in Caracas Valley,Venezuela

Biomonitoring of PAH air pollution using lichens was carried out. Sixteen PAHs were studied in 11 locations along the valley of Caracas (Venezuela). The results of this work indicate that 14 of the 16 analysed PAHs were highly accumulated into the lichen thalli of Pyxine coralligera Malme. PAH levels in the samples revealed that the several volatile PAHs (naphthalene, acenaphtylene, acenaphtene, and fluoranthene) have the highest levels in the majority of the studied locations. The fluoranthene/pyrene and phenantrene/antracene ratios suggested that the major sources of PAHs are anthropogenic, mainly associated with gasoline and diesel combustion (pyrolytic) and unburnt oil derivates (petrogenic). The total PAH concentrations obtained in the present study were in the range of 0.24 to 9.08?µg/g, similar to those reported by other works in European and Asian cities.     

Topological laminations on surfaces

We present and prove a topological characterization of geodesic laminations on hyperbolic surfaces of finite type.     

原子光谱和X射线衍射研究禄丰恐龙化石与围岩特征

迄今为止,禄丰老长箐是世界挖掘恐龙化石较多、涵盖时间最长(含有早、中两个侏罗纪的化石)的地区。老长箐恐龙化石的发掘,为古生物研究提供了得天独厚的实验基地。文章首次对该地区3个不同层位的恐龙化石及其围岩的成分和结构做了初步分析。首先采用原子发射光谱分析,发现化石及土样中的含钙量均较高(＞5%);但硅元素的含量则差别较大,在化石中的含硅量较低(3%～8%),围岩中的含硅量较高(＞10%);化石中的含磷量也较高。X射线能谱的进一步分析发现,化石中的主要化学成分是CaCO₃(66%), 其次是SiO₂(17%);围岩中的主要成分是SiO₂(＞80%),其次是CaCO₃(12%)。此外还发现,化石和围岩的最大区别是,化石中含有氟磷酸钙,而围岩中没有该成分。这一点可以作为鉴别伪化石的一个重要特征。文章为化石的鉴别、为人类研究禄丰老长箐恐龙的生态和演化提供了一定的实验依据。     

Determination of microquantities of Be in samples using α-sensitive track etch detectors

A new technique of determining Be content in samples using 4.66 MeV γ-rays is proposed. This energy range is sufficient to knock out the neutron from the ⁹Be nucleaus and to excite the first 2.9 MeV level of the ⁸Be nuclei. 1.5 MeV alpha particles are registered by means of CR-39 or cellulose nitrate detectors. Alpha particles produced in the reaction of γ-rays with Li nuclei which are contained in samples may cause the background. The latter is excluded by heating of samples before irradiation for Li molecules to be evaporated. ¹¹B nuclei do not produce alpha particles at the energy range of γ-rays presented above.The results obtained in the experiments of determining Be content in natural beryl crystal samples are in good agreement with their known chemical composition. Microparticles containing Beryllium were found in soil samples from the Ust-Kamenogorsk are deposit region, which contains 10⁻³ − 10⁻⁴ g/g of Be. The sensitivity of the method is 10⁻⁶ g/g of Be in solids.     

Optimization of the heavy nuclei track etching in olivine crystals from meteorites

The investigation of the track etching velocity dependence for nuclei with Z50 on pH of the etching solution in the olivine crystals from Marjalahti and Eagle Station meteorites, containing galactic cosmic-ray nuclear tracks and also the crystals from Marjalahti meteorite, calibrated at the UNILAC (GSI, Darmstadt) with 14.17 MeV/N ²⁰⁸Pb nuclei, were performed.

The pH of the etching solution were changed from 7.8 to 9.4. It is shown that the optimal track etch condition were realised at pH of etching solution in the interval from 8.4 to 8.8.

The results of the Galactic cosmic-ray nuclei tracks with Z83 revealed in olivine crystals are presented. They were additionally irradiated at 90% to the surface with accelerated 14 MeV/N ¹³²Xe nuclei.     

Electrochemical Determination of Organic Compounds in Automotive Fuels

This article critically reviews the electroanalytical methods devoted for the determination of organic compounds in automotive fuels that can range from contaminants to additives typically introduced into liquid biofuels and liquid fossil fuels. Contaminants such as aldehydes and ketones in bioethanol, free fatty acids and glycerol in biodiesel, and sulfur and nitrogen organic compounds in gasoline and diesel fuel, and additives such as colour markers and antioxidants added to fuels were determined by electroanalytical methods. Special focus is given to electrodes, electrochemical techniques, and sample preparation strategies. Future directions of research on electroanalysis of liquid fuels are presented.     

Designing polymers for nuclear track detection

This article describes our attempts since 1996 to systematically design and synthesize monomers and corresponding polymers for nuclear track detection. So far more than 15 homopolymers/copolymers have been prepared and tested by us for this purpose. Some of these polymers show better track detection characteristics vis-á-vis commercially available poly allyl diglycol carbonate (PADC) track detectors.