法面扫描井间距离的解析算法

法面扫描是分析实钻轨迹偏离程度、邻井防碰、定向井中靶等井间关系的重要方法。然而,传统方法存在2个主要缺陷:一是采用比较井段两端点是否位于法面异侧来判别法面与比较井是否存在交点的方法不具有普遍适用性,可能会遗漏掉邻井防碰的危险点;二是用迭代法来求解法面与比较井的交点,需要进行大量的轨迹插值与比较等方面的计算,计算量大、收敛性差。为此,基于井眼轨迹的空间圆弧模型,发展完善了法面与比较井是否相交的判别方法,并研究提出了求解其交点的解析法。这些方法不需要对比较井进行插值计算,仅需要比较井的设计轨道节点或实钻轨迹测点数据就能得到准确的计算结果,大大减小了计算量。应用实例验证了研究结果的科学性和适用性。

Application of response surface methodology(RSM) for optimization of leaching parameters for ash reduction from low-grade coal

Coal is the world＇s most abundant energy source because of its abundance and relatively low cost. Due to the scarcity in the supply of high-grade coal, it is necessary to use low-.grade coal for fulfilling energy demands of modern civilization. However, due to ItS high ash and moisture content, low-grade coal exerts the substantial impact on their consumption like pyrolysis, liquefaction, gasification and combus- tion process. The present research aimed to develop the efficient technique for the production of clean coal by optimizing the operating parameters with the help of response surface methodology. The effect of three independent variables such as hydrofluoric acid （HF） concentration （10-20% by vo!ume ）,. temper- ature （60-100 ~C）, and time （90-180 min）, for ash reduction from the low-grade coal was Investigated.. A quadratic model was proposed to correlate the independent variables for maximum ash reduction at the optimum process condition by using central composite design （CC.D）method. The study reveals that HF concentration was the most effective parameter for ash reduction in comparison with time and temper- ature. It may be due to the higher F-statistics value for HF concentration, which effects to large extent of ash reduction. The characterization of coal was evaluated by Fourier transform infrared spectroscopy （FTIR） analysis and Field-emission scanning electron microscopy with energy-dispersive X-ray （FESEM- EDX） analysis for confirmation of the ash reduction.

Oxidation characteristics of boron particles

The oxidation characteristics of boron particles, boron-A with the diameter of 2.545 μm and boron-B with the diameter of 10.638 μm, at low temperature（1500 K） have been investigated by thermogravimetry（TG） coupled with simultaneous differential scanning calorimetry（DSC）, infrared and mass spectra. A rapid oxidation stage of boron particles, followed by a slow oxidation stage of sintered particles, is found from the TG and DSC curves. The onset temperatures of the oxidation process of boron-A particles are in the range of 806–889 K, which are at least 105 K lower than those of boron-B at the same condition. As the partial pressure of oxygen increases from 5% to 35%, the onset temperature of boron-A or boron-B particles decreases. However, when the partial pressure of oxygen is above 35%, the onset temperature becomes constant, implying a saturation effect of oxygen on the reaction rate. It indicates that the chemical adsorption of oxygen, i.e. chemical reaction, on the particle surface is the rate-limited step at the beginning of the rapid oxidation stage. Therefore, the first-order chemical reaction model is used to simulate the oxidation of boron particles, even that of the sinter. The average activation energies of the particles are 291.3 kJ/mol for boron-A and 338.4 k J/mol for boron-B. While the average activation energies of the sintered particles are 36.35 k J/mol for boron-A and 31.87 kJ/mol for boron-B. The pre-exponential factor of the particles is -10^4, while that of the sinter is 10^-1. The oxidation rate constant of boron is qualitatively mainly affected by the specific surface of the sample and the thickness of the oxide layer.

Isothermal crystallization of polypropylene/surface modified silica nanocomposites

In the present work, 3-methacryloxypropyltrimethoxy-silane silanized silica （SiO2-WD70） and 9,10-dihydro-9-oxa-10-phospha- phenanthrene-10-oxide immobilized silica （SiO2-WD70-DOPO） nanoparticles were prepared. Silica, SiO2-WD70 and SiO2- WD70-DOPO were incorporated into polypropylene （PP） by melt compounding. Differential scanning calorimetry （DSC）, X-ray diffraction （XRD） and polarized optical microscopy （POM） were employed to investigate the isothermal crystallization behavior of PP and PP/silica composites. The kinetic constant （kn）, and half crystallization time （t1/2） were calculated by Avrami equation, while the surface free energy of folding was calculated by Lauritzen-Hoffman theory. The increased k,, decreased t1/2 and the surface free energy （ere） in the order ofPP, PP/SiO2, PP/SiO2-WD70 and PP/SiO2-WD70-DOPO nanocomposites were attributed to the surface modification of silica. XRD indicated that SiO2-WD70-DOPO addition had no effect on PP crystal structure but accelerated the crystallization rate. POM determined that SiO2-WD70-DOPO addition promoted the nucleation of PP by inducing a higher nucleation density during isothermal conditions. The surface modified nanoparticle SiO2-WD70-DOPO might find possible application as a new type of inorganic nano-sized nucleation agent for PP.