Effect of fluid column dynamics on longitudinal vibrations of an ultra deepwater riser covered by an orifice plug

The paper studies longitudinal vibrations of an ultra-deepwater drilling riser whose bottom end is disconnected from the sea floor and covered by a plug (a blind one or the one with a hole). An elastic shell is used as a model of a riser pipe. The fluid column motion in the riser is described by the Navier–Stokes equation for a compressible fluid. Losses of fluid pressure during its flowing through a hole in the plug are taken into account. Solution of the riser equations is carried out in the frequency domain. Analysis of the effect which the riser length, wave period and height, and the plug-hole diameter on the amplitude of the riser's tension vibrations is conducted. A riser manufactured of strong aluminium alloys, some of prospective materials for ultra deepwater drilling, was considered as a prototype. It has been shown that risers 2000–4000 m long, plug-hole, and a riser 6000 m long with plug-hole of 0.087 m in diameter can withstand wave height of >15 m throughout the frequency range.     

差示FT-Raman和11B NMR方法研究过饱和镁硼酸盐的溶液结构

用差示FT -Raman和11BNMR光谱研究了MgB6O10 ·7 5H2 O、MgB4O7·9H2 O、Mg2 B6O10 ·1 5H2 O三种镁硼酸盐饱和和过饱和溶液的结构机理 ,其结果表明饱和溶液和过饱和溶液中均存在B(OH) 3 、B(OH) -4、B3 O3 (OH) -4、B5O6(OH) 4 -粒子。镁硼酸盐的结晶过程是一个复杂的动力学平衡过程     

Sn-Ni化学镀硅酸钙镁矿物晶须的制备与表征

以硅酸钙镁晶须为原料,采用化学镀方法制备一种镀Sn-Ni硅酸钙镁晶须,并用SEM,XRD,EDS和FT-IR对镀Sn-Ni硅酸钙镁晶须进行表征。结果表明:镀Sn-Ni硅酸钙镁晶须是一种针状结构的硅酸盐晶须材料,除有部分聚集增粗外,其形貌几乎没有变化;镀Sn-Ni硅酸钙镁晶须的主要化学组成为:w(O)48.24%,w(Si)10.78%,w(Mg)5.44%,w(Ca)2.26%,w(Sn)22.45%,w(Ni)2.19%,w(Na)4.38%,w(P)2.46%和w(S)1.80%;镀Sn-Ni硅酸钙镁晶须在1100cm-1～850cm-1强吸收区的振动频率的增加值与在750cm-1～600cm-1弱吸收区的振动频率的降低值均为4.98cm-1;镀Sn-Ni硅酸钙镁晶须的主体结构和化学键没有发生根本上改变,Sn-Ni化学镀在本质上是一种物理包覆过程。该研究为提高矿产资源的综合开发和利用水平提供了一种新的思路和方法。     

土耳其火山沉积硼矿床成矿条件综述

土耳其硼酸盐矿床,集中分布在该国西北的西安拉托尼亚地区。重要矿床有比加迪奇、凯斯特莱克、苏丹泽里、埃默特和基尔卡。这些矿床均发育于障壁山间盆地第三纪浅水湖相沉积中,是干旱、半干旱气候条件下非海洋环境的产物。除碳酸盐、硼酸盐等化学沉积之外,山间盆地还广泛接受碎屑沉积,如砾岩、砂岩、粘土、泥岩,以及大量火山碎屑岩、凝灰岩、层凝灰岩等。矿床不同,沉积学特征亦异,但第三纪沉积均具明显的旋回性或韵律性。所有矿床均与火山活动伴生,二者的密切程度超过世界任何硼酸盐矿床。中国辽吉硼矿带的火山沉积变质硼矿床,也许在变质前与前者在矿化上具有共性,只是后者强调了“变质”成矿。     

盐卤硼酸盐化学ⅩⅩ.：天然含硼盐卤的蒸发相图

在进行青藏高原盐湖含硼盐卤天然蒸发和25℃等温蒸发实验的基础上,绘制成复杂盐卤的蒸发相图。该相图与Na~+、K~+、Mg~(2+)//Cl、SO_4~(2-)—H_2O体系25℃介稳相图基本上相符合。在将蒸发相图与该五元体系平衡溶解度相图进行比较后,从盐溶液化学的角度对蒸发相图的形成原因进行了解释。     

硼酸盐矿物的振动光谱研究：Ⅰ：喇曼光谱特征

本文利用激光喇曼光谱研究了不同类型的硼酸盐矿物,讨论了它们的谱带特征及其归属。研究结果表明,具简单基团的喇曼光谱可以作出比较明确的归属,且与红外光谱结果一致,而同时具三、四配位硼的矿物,其配阴离子虽很复杂,各种谱带相互叠加,但仍可以对主要谱带作出初步的归属。     

Comparative Study of Nucleation by Different Alcoholic Solutions of Benzoin, and Benzoin Dust

Nucleation properties of different alcoholic solutions of Benzoin and Benzoin dust have been studied by varying the seeding temperature in a laboratory Cold Chamber. In the present study, three different alcoholic solutions are being used and these are due to the standard Ethyl alcohol, one higher alcohol i.e. Isopropyle alcohol and one lower alcohol i.e. Methyl alcohol. In addition, Benzil dust and droplets of Acetone and Chloroform have been used to examine if these agents have any ice nucleation ability. It has been observed that all alcoholic solutions of Benzoin have sufficient ice nucleation ability at the negative side of 0^°C, with the maximum concentration occurring at −14.4^°C. In case of Benzoin dust, the nucleation ability is better on the positive side of 0^°C than the negative side. On the other hand, Benzil dust has insignificant nucleation ability and the droplets of two other agents have no nucleation ability at all.Considering the chemical as well as crystalline structure, one can conclude that the presence of OH group in the seeding molecule plays the central role in ice nucleation/hydrate crystal formation. In fact, a number of supplementary experiments like crystal growth in an incubator, XRD analysis and NMR study are performed to identify the nature of crystals formed by Benzoin dust above 0^°C. One can conclude that these are hydrate crystals of Benzoin with water caging around Benzoin crystals.     

四硼酸十八铝晶须制备实验中的原料和产品分析

本文报道了在四硼酸十八铝晶须材料制备实验中，原料明矾、脱水明矾和硼酸，以及制成品四硼酸十八铝晶须的熔样处理和分析方法，同时给出有关分析结果。     

Aluminium grain boundary diffusion in polycrystalline mullite ceramics

Aluminium tracer diffusivities were measured in polycrystalline mullite. The artificial aluminium isotope ²⁶Al was used as tracer isotope. An advanced preparation technique for the ²⁶Al₂O₃ tracer source allowed to apply secondary ion mass spectrometry (SIMS) in order to analyse ²⁶Al depth distributions in the polycrystalline material. Pre-exponential factors and activation enthalpies were determined for compositions of 78 wt.% Al₂O₃, 22 wt.% SiO₂ (high-alumina material) and of 72 wt.% Al₂O₃, 28 wt.% SiO₂ (low-alumina material), respectively. A strong dependence of the ²⁶Al grain boundary diffusivity on the composition is observed. The results are discussed in comparison to previous data on grain boundary diffusivities of oxygen in mullite samples from the same batch. Dedicated to Prof. Hermann Schmalzried on the occasion of his 75th birthday.     

青海大柴旦地区低品位硼矿富集加工技术创新效果分析

青海省大柴旦地区是我国硼资源主要产地之一,经数十年的开采,矿体中富矿已基本枯竭。通过对大柴旦地区硼资源的分析,重点介绍了分级富集与沉矿浮选联合流程法和直接分级法两种低品位硼矿富集技术,同时对两种技术的内容、路线以及创新效果进行了讨论,并由创新效果的比较分析,得出两种方法的优点和创新性,同时提出对未来低品位硼矿富集技术的展望。