Marc Hoit

NCSU's Virtual Computing Lab: A Cloud Computing Solution

The delivery of many diverse computing services over the Internet, with flexible provisioning, has led to much greater efficiency, substantial cost savings, and many ways to enable and empower end users. NCSUs own experience with cloud computing, through its Virtual Computing Lab, indicates that this approach would be beneficial to a much wider audience.ays to enable and empower end users. NCSUs own experience with cloud computing, through its Virtual Computing Lab, indicates that this approach would be beneficial to a much wider audience.

An equation numbering algorithm based on a minimum front criteria

Abstract An algorithm is presented which defines the optimum equation numbering sequence for the Gauss Elimination solution of finite element systems. The equation numbering sequence generated is identical to the equation solving sequence used in the well-known “Frontal Method”, in which the next equation to be eliminated is determined by the minimum front criteria. After the numbering sequence is determined, the equations are stored in profile form. Therefore, the new algorithm is named the “Profile-Front Minimization” or “PFM” algorithm. In this paper, existing methods for equation renumbering are discussed. The theoretical development and the computer implementation of the PFM method are then presented. Solution times and storage requirements for several examples are summarized and the PFM algorithm is compared to other techniques. In all the examples studied, the PFM algorithm produced equation numbering sequences which resulted in the minimum solution times. In addition, the PFM method, for higher order finite element systems, requires significantly less computer storage than other methods. The Fortran listing of the subroutines for the PFM algorithm are give. These can be used directly by Profile or Frontal solvers since both nodal and element numbering sequences are produced. These subroutines have proven to be extremely effective when used on microcomputers.

First-year integrated curricula across engineering education coalitions

The National Science Foundation has supported creation of eight engineering education coalitions: Ecsel, Synthesis, Gateway, SUCCEED, Foundation, Greenfield, Academy and Scceme. One common area of work among these coalitions has been restructuring first-year engineering curricula. Within some of the Coalitions, schools have designed and implemented integrated first-year curricula. The purpose of this paper is to survey the different pilots that have been developed, abstract some design alternatives which can be explored by schools interested in developing an integrated first-year curriculum, indicated some logistical challenges, and present brief descriptions of various curricula along with highlights of the assessment results which have been obtained.

A computer adaptive language for the development of structural analysis programs

Abstract A group of FORTRAN 77 subroutines is presented which are designed to augment the standard fortran language and to produce a new higher-order, machine-independent language for the development of structural engineering software. The group of subroutines which comprise the Computer Adaptive Language for the development of Structural Analysis Programs, CAL/SAP, is designed to operate effectively on micro, supermini and mainframe computers. The CAL/SAP system has been used as the basis for the development of the SAP-80 series of programs and for CAL-80, a series of interactive programs for Computer Assisted Learning of structural analysis and design. The subroutines which define the CAL/SAP development system are divided into the following three categories: • • First, a series of free-field input routines allows input data to be specified in a consistent manner, in arbitrary order, with optional name identification and in arithmetic statement form. • • Second, a set of incore data management subroutines allows dynamic storage allocation to be accomplished with integer, real and ASCII data with a minimum of programming effort. These subroutines eliminate paging problems on modern super minicomputers with virtual operating systems. • • Third, an out-of-core data management system allows different programs to access the same data. Simple operations allow data transfer between the in and out-of-core systems. The out-of-core data base provides for sequential, direct access and bulk data files. Communication between different data bases allows techniques such as multilevel substructure analysis to be implemented with a minimum of programming. The use of the CAL/SAP development system allows computer programs to be rapidly developed and maintained. Also, it can be used to upgrade existing software in order to obtain modularity and to operate efficiently on the new generation of computer systems. The purpose of this paper is to present the CAL/SAP development system and to illustrate that computer independent programs in structural engineering and computational mechanics can be developed which operate on both large and small computers.

Physics-of-failure assessment of a cruise control module

Abstract The purpose of a cruise control system is to accurately maintain the driver’s desired set speed, without intervention from the driver, by actuating the throttle-accelerator pedal linkage. Over the past five years, owners of a particular cruise control have complained that it did not operate properly. Complaints ranged from not engaging upon command, to the cruise unexpectedly accelerating past the desired speed. A common thread among all the complaints was the intermittent nature of the problems. More than 96% of the reported failed modules removed from vehicles and returned to the company, passed bench tests. This paper presents a physics-of-failure process to identify, induce and analyze failure mechanisms causing intermittent failures, high warranty returns and cannot duplicate (CND) problems of the digital electronic cruise control module (CCM). In addition, we explain why the manufacturer’s tests were not representative of the actual automotive environments, nor were they conducted in a manner to access actual failures. We conclude with a recommendation for a physics-of-failure approach for future product development.

Data storage and extraction in engineering software using XML

Most engineering analysis programs rely on customized procedures for storing and accessing scientific data. The size of the data set needed to characterize an engineering problem can be substantial, particularly as the problem increases in complexity. This paper presents a methodology for greatly improving the accessibility of scientific data using the Extensible Markup Language (XML) to define a consistent procedure for data storage and retrieval. When the data is expressed in an XML format, any portion of the data set can be easily accessed by interfacing with an XML parser. Examples are provided for automating design calculations and CAD drawings.

The Florida Pier Analysis Program Methods and Models for Pier Analysis and Design

The Florida Pier Analysis Program (FLPIER) was developed by the University of Florida Department of Civil Engineering in conjunction with the Florida Department of Transportation (FDOT) Structures Division. The program was developed in order to give pier designers a comprehensive model development and analysis tool to optimize pier designs. The current version is a nonlinear, static, soil-structure interaction suite of programs that run on a personal computer and include group pile effects, layered soil, pier columns and cap, high mast lighting, sound, and retaining walls. The program was designed to allow input to be specified graphically using “designer variables” such as spacing, offsets, number of columns, and so forth. Its use has reduced the time for model development and analysis from days to under an hour. The numerical modeling techniques used have been compared with experimental data and give highly accurate results leading to an improved overall design and reduced costs.

Updated profile front minimization algorithm

An updated version of the Profile Front Minimization (PFM) nodal renumbering algorithm is presented. The new version is an order of magnitude faster and the resulting numbering produces improved profile and wavefront characteristics. The algorithm is compared to other commonly used algorithms. The comparisons are based on a set of standard test problems proposed by Everstine. The results indicate that PFM is competitive and a suitable alternative to these other methods. In addition, the new algorithm is efficient in terms of storage requirements and code size, making it easy to implement in existing finite element codes.

A 14-Point reduced integration scheme for solid elements

Abstract A 14-point integration scheme for use with solid brick elements is presented. A 14-point scheme which mimics the Gauss 3 × 3 × 3 point integration at almost half the computational cost is derived in this paper. The scheme is tested using a 20-node solid element using a set of standard test problems. By relaxing the 14-point integration, the 20-node solid element produces excellent results.

PROBABILISTIC DESIGN AND OPTIMIZATION OF REINFORCED CONCRETE FRAMES

Abstract A structural optimization algorithm which includes global displacements as decision variables is presented. The formulation addresses the possibility of using a universal procedure for obtaining optimal solutions independently of local code restrictions. A comparison of current ACI code safety requirements and reliability constraints with examples of optimal limit design techniques is presented. The flexural performance of the elements was evaluated as a function of the actual stress-strain diagrams of the materials. For the non-linear case, formation of fictitious rotational hinges was allowed and the equilibrium constraints were updated accordingly. The adequacy of the frames was guaranteed by imposing constraints, representing the maximum probability of failure of the members and the global displacements allowed, combined with a prescribed limited system probability of failure.