On the geometric factors in fractured media

Abstract

In double‐porosity and multiple continuum models the fractured rock domain can be simplified as two overlapping continua, one for the matrix block system and the other for the fracture network. In this case, it is necessary to define an exchange term accounting for the transfer of fluid and solute masses between the two continua. A newly derived geometric parameter appears in the fluid exchange term, and is valid for any point‐centered block. The geometric parameter is more general and has a clear physical meaning. It is a function of both the shape and the size of the matrix block and agrees well with the double porosity model. The geometric center and conductance of the element is different under the quasi‐steady state compared to the steady state. Quasi‐steady condition is more suitable than steady state condition for modeling fractured media.     

Preparation of layered nickel aluminium double hydroxide from waste solution of nickel

The separation of nickel has been carried out from a waste solution containing 3.18 g/L Ni with other impurities such as Fe, Zn, Cu and As. Iron was removed by precipitation and Cu and Zn were removed by solvent extraction using LIX 622N and NaTOPS-99, respectively. After removal of all these impurities nickel was extracted by 1.5 M NaTOPS-99 in two counter-current stages at A:O ratio of 3:1 and the loaded organic was stripped with 30 g/L H₂SO₄ at phase ratio of unity. The strip solution of nickel was treated with Al₂(NO)₃ · 9H₂O for co-precipitation by increasing the pH of solution with 1 M NaOH up to 10. The Ni–Al layered double hydroxide was confirmed through XRD characterization.     

硫酸钙与氢气反应的动力学研究

通过综合热分析仪研究了硫酸钙与氢气的反应过程,用Flynn-Wall-Ozawa公式,求出不同转化率下的活化能,并将其外推为零,得到无副反应时的活化能Eα→0=198.02kJ/mol。然后运用Coast-Redfern积分式,计算出30种机理函数和不同升温速率所对应的活化能E,并将升温速率外推为零,得到热平衡态的Eβ→0。通过比较Eα→0与Eβ→0,确定反应过程的最概然函数。     

半桥驱动芯片中LDMOS的设计仿真

借助工艺和器件仿真软件,对一种用于功率MOSFET和IGBT栅极驱动的半桥驱动芯片中的横向高压功率器件LDMOS进行了设计与仿真。该器件采用了双RESURF技术及双层浮空场板结构,通过对双层浮空场板层之间的距离以及双RESURF结构的ptop层的长度和浓度的优化设计,利用传统的Bi-CMOS工艺获得击穿电压689V和比导通电阻273×10–3.cm2的LDMOS。     

一种基于随机矩阵的双因子身份验证方法

身份认证在网络应用系统中起着重要作用。该文介绍一种基于随机矩阵的双因子身份验证方法的实现思路，以随机矩阵的行列坐标作为相互约束条件，提出了一种全新的基于互联网上的电子身份的密码验证方法。此方法具有很强的防泄漏、防黑客盗号、防木马盗号的能力。     

实现IPv4向IPv6过渡的双协议栈技术和隧道技术

该文介绍了两种向IPv6过渡的策略,阐述了向IPv6过渡的迫切性,讨论了使用双协议栈和使用隧道技术两种基本原理。以及目前向IPv6过渡的状况。     

铀溶液临界装置抗震分析

铀溶液临界装置充装大量液体,抗震分析采用简捷有效的附加质量法处理液动压力的关键问题.容器高架夹套、质量分布上重下轻以及连接松脱的结构特点导致系统抗震能力较差.对此,通过对交叉加固和平板约束方案的对比分析,最终采用在装置上部增加约束的方法极大提高了系统抗震能力,使装置抗震性能满足了有关要求,并为设计提供了可行的结构优化方案.     

分数槽绕组排列与接线

通过对分数槽电动热相量讨论分析，得出分数槽绕组排列与接线原理。     

Preparation and characterization of Mg–Al layered double hydroxides intercalated with benzenesulfonate and benzenedisulfonate

Mg–Al layered double hydroxides (Mg–Al LDHs) intercalated with benzenesulfonate (BS^–) and benzenedisulfonate (BDS^2–) ions were prepared by coprecipitation and characterized by X-ray diffraction, FT-IR spectroscopy, and chemical analyses. The intercalated BS^– and BDS^2– maintained their intrinsic molecular structures within the Mg–Al LDH interlayers. At low intercalation levels, the benzene ring of BS^– in BS · Mg–Al LDH was inclined at 30° relative to the plane of the brucite-like layers of Mg–Al LDH. With increasing BS^– content, the benzene ring adopted an additional configuration perpendicular to the Mg–Al LDH layers. In BDS-intercalated Mg–Al LDH, the benzene ring of BDS^2– was tilted at 26° relative to the plane of the Mg–Al LDH layers. Intercalation levels of BDS^2– were smaller than those of BS^– despite the greater charge density of BDS^2–, which was likely attributable to a greater degree of electrostatic repulsion between intercalated anions.     

双标记药物中放射性强度比值测定方法的应用 双标记药物中放射性强度比值测定方法的应用

研究药物体内代谢过程都要涉及药物的分离、定性和定量,以往多采用化学方法进行检测分析,但对其样品的处理要求高、操作繁琐、灵敏度低、有时尚难满足实验要求;也有利用高速液相色谱、色谱-质谱联用技术对药物进行分析,操作虽然简单了一些,但仍有对样品处理要求较高的问题。如此,我们设想采用双标记药物后,测定两种放射性核素强度的 研究药物体内代谢过程都要涉及药物的分离、定性和定量,以往多采用化学方法进行检测分析,但对其样品的处理要求高、操作繁琐、灵敏度低、有时尚难满足实验要求;也有利用高速液相色谱、色谱-质谱联用技术对药物进行分析,操作虽然简单了一些,但仍有对样品处理要求较高的问题。如此,我们设想采用双标记药物后,测定两种放射性核素强度的