Surface tension of liquid silicon

Experimental data on the surface tension of liquid silicon are analyzed. The effect of oxygen and other impurities is discussed. A large body of data is statistically processed. The expression = 0.82–0.3 × 10^–3 (T – 1685) (J/m²) is recommended for the surface tension as a function of temperature in the range from 1685 to 1830 K.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 38, No. 6, 2004, pp. 699–707.Original Russian Text Copyright © 2004 by Shishkin, Basin.     

Greedily computing associative aggregations on sliding windows

We present an algorithm for combining the elements of subsequences of a sequence with an associative operator. The subsequences are given by a sliding window of varying size. Our algorithm is greedy and computes the result with the minimal number of operator applications.     

Automated analysis of security-design models

We have previously proposed SecureUML, an expressive UML-based language for constructing security-design models, which are models that combine design specifications for distributed systems with specifications of their security policies. Here, we show how to automate the analysis of such models in a semantically precise and meaningful way. In our approach, models are formalized together with scenarios that represent possible run-time instances. Queries about properties of the security policy modeled are expressed as formulas in UML’s Object Constraint Language. The policy may include both declarative aspects, i.e., static access-control information such as the assignment of users and permissions to roles, and programmatic aspects, which depend on dynamic information, namely the satisfaction of authorization constraints in a given scenario. We show how such properties can be evaluated, completely automatically, in the context of the metamodel of the security-design language. We demonstrate, through examples, that this approach can be used to formalize and check non-trivial security properties. The approach has been implemented in the SecureMOVA tool and all of the examples presented have been checked using this tool.     

Optimal filtering for polynomial system states with polynomial multiplicative noise

In this paper, the optimal filtering problem for polynomial system states with polynomial multiplicative noise over linear observations is treated proceeding from the general expression for the stochastic Ito differential of the optimal estimate and the error variance. As a result, the Ito differentials for the optimal estimate and error variance corresponding to the stated filtering problem are first derived. The procedure for obtaining a closed system of the filtering equations for any polynomial state with polynomial multiplicative noise over linear observations is then established, which yields the explicit closed form of the filtering equations in the particular cases of a linear state equation with linear multiplicative noise and a bilinear state equation with bilinear multiplicative noise. In the example, performance of the designed optimal filter is verified for a quadratic state with a quadratic multiplicative noise over linear observations against the optimal filter for a quadratic state with a state‐independent noise and a conventional extended Kalman–Bucy filter. Copyright © 2006 John Wiley & Sons, Ltd.     

Optimal control for a polynomial system with a quadratic criterion over infinite horizon

This paper proposes an optimal control algorithm for a polynomial system with a quadratic criterion over infinite horizon. The designed regulator gives a closed-form solution to the infinite horizon optimal control problem for a polynomial system with a quadratic criterion. The obtained solution consists of a feedback control law obtained by solving a Riccati algebraic equation dependent on the state. Numerical simulations in the example show advantages of the developed algorithm.     

Optimal controller for uncertain stochastic polynomial systems with deterministic disturbances

This article presents the optimal quadratic-Gaussian controller for uncertain stochastic polynomial systems with unknown coefficients and matched deterministic disturbances over linear observations and a quadratic criterion. The optimal closed-form controller equations are obtained through the separation principle, whose applicability to the considered problem is substantiated. As intermediate results, this article gives closed-form solutions of the optimal regulator, controller and identifier problems for stochastic polynomial systems with linear control input and a quadratic criterion. The original problem for uncertain stochastic polynomial systems with matched deterministic disturbances is solved using the integral sliding mode algorithm. Performance of the obtained optimal controller is verified in the illustrative example against the conventional quadratic-Gaussian controller that is optimal for stochastic polynomial systems with known parameters and without deterministic disturbances. Simulation graphs demonstrating overall performance and computational accuracy of the designed optimal controller are included.     

四川盆地天然气录井特点与识别方法

四川盆地天然气录井具有隐蔽性强的特点，使过平衡钻井中不易识别、发现气层，易发生井漏与井喷，对产层的解释评价也有一定难度。为此，总结和归纳了四川盆地天然气录井特点与识别方法：在常规钻井条件下的天然气识别方法主要靠气测，辅之以钻时、岩屑录井技术，并及时进行小层对比，以确保发现储层。欠平衡钻井的天然气识别方法主要有4种：①气测录井仍是判断油气显示的主要依据；②精细分析钻时，从微弱变化中明查储层；③正确录取和鉴别岩屑是及时发现储层的关键；④及时观察出口工程参数及火焰的变化，是发现气层的佐证。天然气录井中的井控工作包括：搞好地质预报预告，及时发现油气水漏显示与预警，加强坐岗记录以保证钻井安全。     

断陷盆地群的含油气系统特征——以海拉尔盆地乌尔逊、贝尔凹陷为例

从构造、地层及生、储、盖组合特征出发，以含油气系统的基本原理为依据，划分和比较了乌尔逊、贝尔凹陷6个含油气系统的基本特征，根据各含油气系统的断陷构造样式、断裂发育特征、油气藏类型和分布，总结出双断反转型、断超反转型、断超串型型、简单双断型和无机CO2型共5种类型的含油气系统模式，以此为依据预测了海拉尔盆地其它次级断陷的含油气系统类型。