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As the complexity and size of the projects undertaken by horizontal directional drilling (HDD) contractors rapidly increase, there is a growing need for the development of dedicated software designed to meet the industry's special needs and requirements. This paper presents the results of a survey of the HDD industry's software needs as well as a summary of commercially available software specifically designed for this industry. In addition, the development of two computerized applications tailored for the HDD industry are described. The first of these applications is an integrated data management system that combines asset management, cost control, estimating, and project tracking capabilities, enabling decision makers to closely monitor field performance in terms of expenditure and productivity. The second application is a simulation model developed for optimizing the utilization of drilling rigs and hydro-vacuum trucks on large-scale urban projects. Both applications are designed to improve the planning, estimating, and productivity of directional drilling projects, ultimately reducing the cost of expanding underground infrastructure networks. [ABSTRACT FROM AUTHOR]

A method is presented for estimating mean crossing rates for the stationary response of linear systems to non-normal excitation modeled by polynomials of Gaussian processes. Information about the non-Gaussian system response is derived in terms of statistical moments that are accurately calculated from a closed system of linear algebraic equations. This information is used to construct the most unbiased response distribution using the maximum entropy principle, a consistent method of inductive inference. Mean crossing rates are then estimated by mapping a standard Gaussian process into the nonGaussian response and by using the property that the two processes have nearly equal crossing rates. The proposed method is applied to compute mean crossing rates and probability density functions for the response of a simple oscillator to the following types of excitation processes: the square of the Ornstein-Uhlenbeck process, and third degree polynomials of Gaussian processes. [ABSTRACT FROM AUTHOR]

The behavior and modeling of connections, which form the essential bases of accounting for connection flexibility in the analysis and design of steel-frame structures, have been under investigation since the 1930s. This technical note presents a sufficient condition on the moment-rotation characteristic of the connection model that will ensure uniqueness in the analysis of steel frames when nonlinear semirigid connection behavior is taken into account. This sufficient condition should be useful in the development of various connection models. [ABSTRACT FROM AUTHOR]