一类新的反Smarandache几何级数周期行列式

本文定义了一类新的反Smarandache几何级数周期行列式,并利用初等数论的方法和行列式的性质,对这类行列式进行了研究,给出了它们的通项公式。     

长治市土壤墒情预测方法探讨

反映旱与涝的主要指标是土壤含水率。通过对长治市墒情测验历史资料分析及降水、蒸发等因子对土壤含水率变化的分析，根据有关下渗原理，总结墒情计算方法，得出墒情预测公式。     

非均匀沙分级推移质公式

根据近底泥沙交换的随机-力学模式及输沙率概率分布，从理论上建立了非均匀沙任意粒级推移质输沙率的新公式。采用作者提出的分级起动概率和颗粒跳跃速度表达式处理有关参数，而公式所及常数则由均匀沙输移试验资料确定。由此获得的非均匀沙分级推移质公式物理概念清楚、数学处理严密、能自动适应均匀沙情形。用非均匀沙分级输移试验资料的验证结果表明，理论能合理地描述非均匀沙推移质运动的客观规律。     

ON CALCULATIONS OF THE DRAG COEFFICIENT Cd AND THE FALL VELOCITY ω OF SPHERICAL BODIES

ＯＮＣＡＬＣＵＬＡＴＩＯＮＳＯＦＴＨＥＤＲＡＧＣＯＥＦＦＩＣＩＥＮＴＣｄＡＮＤＴＨＥＦＡＬＬＶＥＬＯＣＩＴＹωＯＦＳＰＨＥＲＩＣＡＬＢＯＤＩＥＳＸｉａｎｇＺｈａｏ－ｆａ（ＩｎｓｔｉｔｕｔｅｏｆＥｓｔｕａｒｙａｎｄＣｏａｓｔｌａｎｄ，ＹｅｌｌｏｗＲｉｖ...     

关于曲线积分和曲面积分教学中几个难点的突破

加强曲线、曲面积分概念讲解,标准化曲线、曲面积分的计算程序,沟通有关积分之间关系,以消除学生 对斯托克斯等公式的深奥感,有效地突破了曲线、曲面积分教学中的几个难点。     

抛石护岸防冲的几个问题

根据河湾迎流顶冲位置和河床冲深，确定护岸范围和优选护岸护底方案。对于抛石护岸所应用的土工织物滤层的规格和国外典型实例作了介绍，并分析试验资料，给出了抛石大小和抛石落距的计算公式。     

双面滑动交线方位角及倾角计算式推求

地质人员推求双面滑动交线方位角及倾角,采用赤平投影作图法,手工操作和计算机操作均可;但是,习惯于用数学解析方法的设计人员常感到不够直观,使用不便。文章所推导的这2个角的计算式,表达较为简明,操作要求清楚,可供试用。     

Computing the covariance of two Brownian area integrals

We compute the expected product of two correlated Brownian area integrals, a problem that arises in the analysis of a popular sorting algorithm. Along the way we find three different formulas for the expectation of the product of the absolute values of two standard normal random variables with correlation θ . These two formulas are found: (a) via conditioning and the non-central chi-square distribution; (b) via Mehler's formula; (c) by representing the correlated normal random variables in terms of independent normal's and integration using polar coordinates.     

Covariance formulas via marginal martingw

Prenctice and Cai recently introduced and studied the function C defined as the covariance function of the two marginal counting process martingales of a pair of dependent survival times (T₁, T₂ ). They show that the function C together with the marginal distributions determines the joint survival function F of (T₁, T₂ ). In this note we show how the key characterizing equation of Prentice and Cai yields a formula for the covariance of T₁ and T₂ in termsof the marginal mean residual life functions and C. The resulting formula generalizes a formula for the variance of a one-dimensional random variable Tdueto Pyke (1965). We also explore several generalizations of the covariance formula, and obtain a valid k-dimensional version of the Prentice and Cai formula.     

Bridging the gap between a stationary point process and its Palm distribution

In the context of stationary point processes measurements are usually made from a time point chosen at random or from an occurrence chosen at random. That is, either the stationary distribution P or its Palm distribution P° is the ruling probability measure. In this paper an approach is presented to bridge the gap between these distributions. We consider probability measures which give exactly the same events zero probability as P°, having simple relations with P . Relations between P and P° are derived with these intermediate measures as bridges. With the resulting Radon-Nikodym densities several well-known results can be proved easily. New results are derived. As a corollary of cross ergodic theorems a conditional version of the well-known inversion formula is proved. Several approximations of P° are considered, for instance the local characterization of P^o as a limit of conditional probability measures P° N The total variation distance between P° and P₁ can be expressed in terms of the P-distribution function of the forward recurrence time.