A new ground resistance was developed for use in existing vertical bore heat exchanger VBHEx design algorithms. The new ground resistance accounts for the added heat transfer mode of convection due to groundwater flow by using as its foundation the solution for a moving line heat source. The combined ground resistance is presented in terms of the dimensionless Fourier and Peclet parameters. Results show that significant convection heat transfer may occur within a variety of hydrogeological regimes, particularly when the Peclet number is larger than 0.01. Since the new model captures the influence of groundwater flow, the resulting ground resistance differs markedly from the conduction-only ground resistance currently used in many vertical borehole heat exchanger design algorithms.

This paper is written to contribute a software, named WinTruss, with illustration, for analyzing trusses. The software is a resulting product of a design project by a senior student in a sequence of two courses in Creative Project Design for mechanical engineering students at the University of Arkansas. WinTruss runs on PC Windows 95 and later. Being easy-to-use, intuitive, flexible, and powerful, this software is in the process of being made available to instructors and students at Arkansas for enriching the learning experience of students in courses that involve the analysis and design of trusses. The built-in "User Name and ID" dialog box, to be filled out by the user just before submitting the input truss for computer solution, and the "time stamp" on the hard copy of the solution are special pedagogical features. These features allow an instructor to better monitor the actual computer usage by individual students as assignments in a course.