An efficient hierarchicaltraversal algorithm for ray tracing

Ray tracing has been shown to be an excellent technique for rendering realistic images. However, it is important to reduce the lengthy computation time resulting from the brute-force nature of the original ray-tracing algorithms. In this paper, two ideas are proposed to speep up the well-known hierarchical subdivision method. First, a new hierarchy traversal scheme is described to reduce the number of raybounding volume intersection tests for secondary rays. Then, a plane-sweep method is proposed to make fewer intersection checks for eye rays. Experiments and discussions are presented to prove the feasibility of our methods.     

济钢中板厂加快技术创新的对策

本文通过对中板厂近年来技术改造后工艺装置和技术水平的分析，并结合中国加入WTO后对中国钢铁企业面临全球化市场竞争严峻性的认识，提出了中板厂在实现高产生产模式后，应加快技术创新的步伐，尽快完成由高产向优质、多品种、低消耗的高效化生产模式转化的主导思想、措施及建议。     

Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field

The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magneticfield was investigated both theoretically and experimentally The separation efficiency was calculated based on thetrajectory method and compared with experimental results. It is found that the separation efficiency is a functilnondimensional parameters t_i·d_p~2B_e~2/μ_fμ_eα~2 and α/δ.The effective way to improve the separation efficiency is to increasethe effective magnetic flux density and decrease the pipe radius. and the value of α/δ should be kept about 2 in orderto obtain the optimum separation efficiency.     

微重力落塔电磁悬吊、释放技术研究

论述了微重力落塔电磁悬吊、释放、提升机构的关键技术,电磁释放过程的特性分析以及微重力落塔实际试验的情况。分析说明:悬吊、释放性能的好坏决定了试验落舱的微重力水平,也是微重力落塔试验能否成功的关键技术。     

Electrical Resistance Measurement of Glass Transition and Crystallization Characteristics of Zr—Al—Cu—Ni Metallic Glasses

In this paper,glass transition and thermal stability of the Zr-Al-Cu-Ni metallic glasses were investigated by using electrical resistance measurement(ERM),DSC and X-ray diffraction techniques.The experimental results show that the ERM is capable of detecting the glass transition of the amorphous alloys and can help to distinguish the crystallization products of the Zr-Al-Cu-Ni metallic glasses owing to the difference of the electrical resistivity between the precipitation phases.     

非晶Sm5Fe74.3Nb1.5Si11.7B4.5C2.5Cu0.5合金经预退火后的晶化动力学的DTA研究

研究了非晶Sm5Fe74.3Nb1.5Si11.7B4.5C2.5Cu0.5合金经400℃，保温10min预退火后的晶化动力学。结果表明；该合金的晶化相为α-Fe固溶体和Sm2Fe17Cx金属间化合物，两相的晶化表观激活能分别为557KJ/mol和514KJ/mol，当晶化体积分数为60%时，α-Fe相的晶化激活能达极大值；Sm2Fe17Cx相晶化激活能则随其晶化体积分数的增加而逐渐减小。     

添加CaF2-YF3的AlN陶瓷的热导率

用CaF2和YF3做添加剂，在1750℃制备了热导率高于170W/m.K的的AlN陶瓷，并用XRD和SEM研究了AlN陶瓷在烧结过程中的相组成，微结构以及晶格参数的变化，并讨论了其对热导率的影响，研究发现，当使用CaF2-YF3做添加剂时，微结构差异对AlN陶瓷热导率的影响很小，AlN陶瓷的热导率主要由AlN晶格氧缺陷浓度决定，由于CaF2-YF3能有效降低AlN颗粒表面的氧含量，从而有利于获得高的热导率。     

显式BEZIER三角曲面的构造及其在离散数据插值中的应用

本文较系统地讨论了显式Bezier三角曲面的Clough-Tocher分割构造方法，并从工程应用角度提出了一种准C‘连续的Bezier三角曲面。由这种准C‘连续的Bezier三角曲面，通过进一步求解整体C‘连续的Bezier三角曲面在解决3D离散数据的曲面插值中取得了较好的应用效果。     

Synthesis and aqueous solution behaviors of sodium sulfonate‐terminated dendritic poly(ester‐amine)

Sodium sulfonate‐terminated dendritic poly(ester‐amine) (SPEA) was synthesized by sulfonation of acrylic double bond‐terminated dendritic poly(ester‐amine) (APEA) with sodium hydrogen sulfite (NaHSO₃) in mixture of diglycol and 2‐butanone under normal pressure. The structure of SPEA was characterized by IR, ¹H‐NMR, and elemental analysis. SPEA was water‐soluble. 1.0–40.0% (mass) SPEA aqueous solutions appeared as dilatant fluid. When pH value varied from 1.5 to 12.0, the viscosity of 1–5% (mass) SPEA aqueous solutions changed very small, and the electric conductivity almost kept stable within pH 3.0–10.0. The relationship between the viscosity and the concentration of SPEA water solutions was similar to that of NaCl water solutions. The surface tension of SPEA water solutions was lower than that of polyethylene glycol 2000 water solutions with the same concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Green and self-lubricating polyoxymethylene composites filled with low-density polyethylene and rice husk flour

Polyoxymethylene (POM) composites filled with low-density polyethylene (LDPE) and rice husk flour (RHF) were prepared by injection molding. The POM/5 wt % LDPE/7.5 wt % RHF composite exhibited the lowest wear rate, whereas the coefficient of friction remained low, and the POM/5 wt % LDPE/5 wt % RHF composite had the best mechanical properties. X-ray diffraction analysis was carried out, and the worn surfaces were examined with scanning electron microscopy. The results showed that the addition of the filler reduced the crystallinity degree of the POM composites. The main wear mechanism for unfilled POM was adhesion, whereas for the POM composites, wear seemed to occur mainly by fatigue and abrasion. It was experimentally confirmed that the POM composite filled with LDPE and RHF, which is well-performing, low-cost, and environmentally friendly, could be a potential material for tribological applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008