横波速度径向层析成像方法及应用研究

近来三维声波成像技术的一个重要进展是利用偶极子弯曲波反演地层径向横波速度剖面。确定地层径向横波速度变化对评价井壁稳定性、估算地应力和优化油藏生产等有着重要的意义。偶极横波测井激发的弯曲波低频探测较深,高频探测较浅,本文根据偶极弯曲波的频散特征,采用约束反演的方法求取地层径向横波速度变化。在实际测井中,经常会遇到偶极子弯曲波的频散曲线在高频时缺失或者不准确的情况,这会使约束反演方法产生误差。针对这一现象,本文提出利用理论频散数据进行高频约束,并通过数值模拟验证了改进后约束反演方法的正确性。本文给出了一个致密气层的横波速度径向剖面综合应用实例,发现地层径向横波速度变化程度与岩石脆性有很好的对应关系,最终的压裂效果由压前、压后正交偶极横波各向异性的变化得到了印证,压裂后油气产量提高。     

二维电磁逆散射问题的时域高斯-牛顿反演算法

为了直接利用超宽带(UWB)时域测量数据,同时重建二维(2D)目标(OI)的介电常数和电导率,本文将频域高斯-牛顿反演(GNI)算法发展为时域形式.迭代重建过程中,正问题由时域有限差分(FDTD)法求解,而逆问题的病态特性用自适应正则化技术抑制.四类数值算例中,噪声影响均被考虑,仿真结果初步证实了改进算法的可行性和鲁棒性.重建图像呈现超分辨率(SR),有望应用到早期乳腺癌检测等实际问题中.     

Some notes on identities for Dirichlet L-functions

Let q ≥ 3 be an integer, and χ be a Dirichlet character modulo q, L(s, χ) denote the Dirichlet L-function corresponding to χ. In this paper, we show some early information on the mean value of the Dirichlet L-functions and give some new identities for     

Asymptotic probability of majority inversion under a general binomial voting model

We obtain limits on the probability of majority inversion when the number of voters tends to infinity, for a binomial voting model specific to each state with different population sizes, and for different voting quotas in the two stages of the voting procedure. The case of weighted votes at the second stage is also discussed. For an important special case where the limit cannot be determined, we provide an exact expression for the inversion probability, but only for unweighted votes.     

与Smarandache函数有关的一个方程的解的注记

设φ(n)、S(n)分别表示正整数n的Euler函数和Smarandache函数,白海荣和廖群英在[Smarandache函数的几类相关方程的解,数学学报中文版,2019,62(2):247-254]中称方程φ(n)=∑d|nS(d)只有两个解,分别为n=2^5和n=3×2^5.本文指出,这两个数均不是此方程的解,并指出其出错原因是因为他们对M?bius反转公式的错误理解所造成的.     

一种基于正反演过程的油田注水管网计算方法

为了确定油田注水管网中注水方案,采用一种正演反演迭代的算法。该算法的主要思想是:对于油田注水管网首先进行反演计算,计算泵站的需求流量,然后进行正演计算,判断所有注水井是否满足配注要求,如果所有注水井满足配注要求则停止计算,否则减少不满足的注水井一定步长的需求配注流量,进入下一次迭代运算。该算法不需要列写注水管网系统方程组,实现简单,使用迭代方法,适合计算机编程。实验结果表明,该算法具有快速性和准确性。     

SirX: a selective inversion recovery experiment on X‐nuclei for the determination of the exchange rate of slow chemical exchanges between two sites

Nuclear magnetic resonance spectroscopy has proven to be powerful for the study of dynamic processes. A new pulse sequence, SirX, is designed to provide boundary conditions that simplify the McConnell equations. Both an initial rate approximation and a whole curve fitting to the time course of magnetization can be used to calculate the exchange rate. These methods were used to study the exchange kinetics of N,N‐dimethylacetamide. As compared with the well‐established exchange spectroscopy suitable to studies of slow exchange, SirX has the advantage of being less time consuming and capable of providing more reliable kinetic data. Furthermore, by setting the observation on X‐nuclei with larger chemical shift dispersion as compared with an observation on ¹H resonance, SirX extends the upper limit of a reliable determination of exchange rates. Copyright © 2015 John Wiley & Sons, Ltd.     

反转构造对油气成藏的影响

反转构造是含油气盆地中较为常见的构造样式，其对油气聚集、成藏具有重要影响。反转构造主要是由两期方向相反的应力作用的结果，根据应力的不同可将反转构造分为正反转构造和负反转构造，依据反转构造的尺度可将反转构造分为断层的反转、盆地的反转及盆地系的反转。构造反转既可以导致油气运移、聚集，也可以使原有油气藏遭受破坏，导致油气逸散，究竟是否有利取决于反转构造的反转程度。     

Validation of an enantioselective LC–MS/MS method to quantify enantiomers of (±)‐OTX015 in mice plasma: Lack of in vivo inversion of (−)‐OTX015 to its antipode

A highly sensitive, specific and enantioselective assay has been validated for the quantitation of OTX015 enantiomers [(+)‐OTX015 and (−)‐OTX015] in mice plasma on LC–MS/MS‐electrospray ionization as per regulatory guidelines. Protein precipitation was used to extract (±)‐OTX015 enantiomers and internal standard (IS) from mice plasma. The active [(−)‐OTX015] and inactive [(+)‐OTX015] enantiomers were resolved on a Chiralpak‐IA column using an isocratic mobile phase (0.2% ammonia/acetonitrile 20 : 80, v /v) at a flow rate of 1.2 mL/min. The total run time was 6.0 min. (+)‐OTX015, (−)‐OTX015 and IS eluted at 3.34, 4.08 and 4.77 min, respectively. The MS/MS ion transitions monitored were m/z 492 → 383 for OTX015 and m/z 457 → 401 for IS. The standard curves for OTX015 enantiomers were linear (r ² > 0.998) in the concentration range 1.03–1030 ng/mL. The inter‐ and intraday precisions were in the range 2.20–13.3 and 8.03–12.1% and 3.80–14.4 and 8.97–13.6% for (+)‐OTX015 and (−)‐OTX015, respectively. Both the enantiomers were found to be stable in a battery of stability studies. This novel method has been applied to the study of stereoselective oral pharmacokinetics of (−)‐OTX015 and unequivocally demonstrated that (−)‐OTX015 does not undergo chiral inversion to its antipode in vivo in mice.