John F. Dannenhoffer

Improving the Effectiveness of Virtual Teams by Adapting Team Processes

Results are presented from a study on virtual teams and whether appropriate early training can positively influence their effectiveness. Sixteen teams that worked together for periods ranging from three months to three years were studied. Team processes that emerged naturally from long-duration teams were formalized and taught to shorter duration teams. These shorter duration teams comprised three different cohorts, each of which received different levels of training. It was found that the adoption of formal procedures and structured processes significantly increased the effectiveness of virtual teams. Tasks that lend themselves to a structured approach were most effectively accomplished during virtual meetings, whereas face-to-face interactions were better for relatively unstructured, discussion intensive tasks. The performance of a virtual team was significantly improved when team processes were adapted to the affordances of the CMC environment. It is shown that this adaptation can occur very rapidly if teams are trained on the technology as well as on work processes that best exploit it.

The Engineering Sketch Pad: A Solid-Modeling, Feature-Based, Web-Enabled System for Building Parametric Geometry

Within the multi-disciplinary analysis and optimization community, there is a strong need for browser-based tools that provide users with the ability to visualize and interact with complex three-dimensional configurations. This need is particularly acute when the designs involve shapeand/or feature-based optimizations. Described herein is a family of open-sources software products that provides such a capability. At the top is a browser-based system, called the Engineering Sketch Pad (ESP), which provides the user the ability to interact with a configuration by building and/or modifying the design parameters and feature tree that define the configuration. ESP is built both upon the WebViewer (which is a WebGL-based visualizer for three-dimensional configurations and data) and upon OpenCSM (which is a constructive solid modeler; it in turn is built upon the EGADS and OpenCASCADE systems). Each of these open-source software components are described as well as the interactions amongst them.

Design Issues in a Cross‐institutional Collaboration on a Distance Education Course

Collaborative learning has been gaining momentum as a promising pedagogy in higher education. Research on student collaboration is increasing. However, one arena is often overlooked—faculty collaboration. In this article, a cross‐institutional faculty collaboration is presented. The context is faculty collaboration on the design of an undergraduate engineering course. Specifically, this paper examines design issues encountered in the faculty collaborations associated with developing, delivering, and redesigning a senior‐level engineering design course that was taught simultaneously at two universities. This course was taught in state‐of‐the‐art distance learning classrooms. Both within class and outside class, participating students and faculty made use of a Web‐based environment that supported a variety of synchronous and asynchronous interactions. The course itself focused on team design projects and provided instruction on the engineering design process, in various specific skills needed for the students’ projects, and on how to function effectively as part of a geographically distributed engineering design team. The participating faculty members represented different backgrounds, academic disciplines, and academic cultures. Issues related to collaborations on development, delivery, and redesign are elaborated. Based on the lessons learned, suggestions for future cross‐institutional faculty collaboration in course development are provided.

Constrained fuzzy logic approximation for indoor comfort and energy optimization

Indoor environmental satisfaction has been receiving considerable attention by many researchers recently. Research has indicated that allowing building occupants to adjust their local environment to their liking increases satisfaction and human performance. However, concern about the possible increase of energy consumption associated with the wide adoption of distributed localized environmental control has limited the use of such systems. In this study, we show how gradient-based optimization can be used to minimize energy consumption of distributed environmental control systems without increasing occupant thermal dissatisfaction. Fuzzy rules have been generated by data from gradient optimization, showing that a fuzzy logic control scheme based on nearest neighbors approximates closely the gradient-based optimized results.

Detached-Eddy Simulation Procedure Targeted for Design

A new detached-eddy simulation procedure, MBFLO, is described for the simulation of turbulent flow over/within arbitrary geometry. This new procedure represents the first step toward developing a turbulent technique that reduces the reliance on traditional turbulence modeling by directly solving for the larger-scale turbulence effects in regions where the computational grid is sufficient to resolve those scales. A goal of this effort was to develop a detached-eddy simulation procedure-for which the time-averaged solution can replace current steady simulation results for design. Because detached-eddy simulation requires the solution of the unsteady Navier-Stokes equations on computational grids that are typically an order in magnitude more dense than their Reynolds-averaged counterparts, special care was taken to make this new procedure computationally efficient. This paper describes the data structure, parallelization, and automation techniques used to produce time-averaged detached-eddy simulation predictions. Results for the turbulent flow through a turbine and compressor cascade at design and offdesign conditions, respectively, are shown to illustrate the technique.

DECOMPOSITION AND PARALLELIZATION STRATEGIES FOR ADAPTIVE GRID-EMBEDDING TECHNIQUES

SUMMARY A two and three-dimensional adaptive-grid procedure for the solution to fluid dynamic problems is presented. This procedure uses grid-embedding (h-refinement) to automatically refine the grid in regions of high gradients and high truncation error. With this adaptation approach, solutions are obtained with a guaranteed level of accuracy using minimum computer resources. For the solution of steady flows, a multiple-grid technique is used to allow disturbance waves to pass through regions of disparate grid spacing and to accelerate convergence. Domain decomposition and computer parallelization techniques are utilized to allow the solution procedure to be executed efficiently on parallel computer platforms. A discussion of these techniques along with a general description of the adaptive grid-embedding procedure is given. Results are provided demonstrating the accuracy and efficiency of the present procedure on a parallel computer.

OpenCSM: An open-source constructive solid modeler for MDAO

The advent of Multi-Disciplinary Analysis and Optimization environments (MDAO) has put increased emphasis on the automatic generation of configuration boundary representations directly from a feature tree (build recipe) and a set of externally-driven parameters. Many commercial computer-aided design systems exist to satisfy this need, but all currently suffer for several limitations: the build recipe is encoded in files with proprietary formats that are hard to generate and/or modify externally; the primitives are pre-defined and it is very difficult to create fully-parametric user-defined primitives; the build process is not explicitly “differentiated”, thus making the gradients required by optimizers available only via finite differences; and, the systems are licensed in such a ways that distributed, simultaneous execution on many computers can be cost prohibitive. Described here is an open-source constructive solid modeler, named OpenCSM, that has been developed to circumvent these limitations. OpenCSM, which is built upon the OpenCASCADE geometry kernel and the EGADS geometry generation system, is freely available on virtually any computing system. The use of OpenCSM as part of NASA’s OpenMDAO optimization system and as the basis for automatic overset grid generation is demonstrated.

Three-dimensional adaptive grid-embedding Euler technique

A new three-dimensional adaptive-grid Euler procedure is presented that automatically detects high-gradient regions in the flow and locally subdivides the computational grid in these regions to provide a uniform, high level of accuracy over the entire domain. A tunable, semistructured data system is utilized that provides global, topological unstructured-grid flexibility along with the efficiency of a local, structured-grid system. In addition, this data structure allows for the flow solution algorithm to be executed on a wide variety of parallel/vector computing platforms. An explicit, lime-marching, control volume procedure is used to integrate the Euler equations to steady state

QUILTS: A TECHNIQUE FOR IMPROVING BOUNDARY REPRESENTATIONS FOR CFD

Many of today’s organizations design and define their products in solid-model-based computer-aided design (CAD) systems. Analysis of these models via computational fluid dynamics (CFD) requires that the grid generator work with the boundary representation that the CAD system automatically produces. Unfortunately, the exact form of the boundary representation is closely linked to the solid model construction process, and is often divorced from the aerodynamic intent of the object. Described herein is a logical extension to traditional boundary representations, called quilts, which gives the analyst the ability to work with the underlying solid model from the perspective of the aerodynamicist, instead of from the perspective of the CAD model builder. For analysts using unstructured grids, the consequence is that the unusually small triangles associated with the sliver faces that result from intersections, fillets, rounds, and other modeling idiosyncrasies will not be produced, thereby improving both the quality and grid-generation speed for many configurations. For analysts using structured grids, the consequence is that the grid can follow the aerodynamic intent of the body rather than the myriad of edges generated during the generation of the solid model; once again, improved grid quality and significantly decreased grid generation time result. Background

Design of Simulated Server Racks for Data Center Research

Conducting experiments on real high-density computer servers can be an expensive and risky task due to the risks associated with unintended inlet temperatures that exceed the server’s red-line temperature limit. Presented herein is the development of the simulated chassis that mimic real computer servers. Briefly, twelve high-power simulated chassis were designed and built to accurately simulate the actual operating conditions of a real computer chassis in a data center. Each simulated chassis is designed to have approximately 300 Pa pressure drop at a flow rate of 600 cfm to represent a real IBM server chassis. Additionally, the simulated chassis are designed to match the thermal mass of a real server. Eight of the simulated chassis were designed to have constant speed fans and variable heating power while the remaining four chassis were designed to have variable speed fans and variable heating power. Further discussions about the design phase of the simulated chassis are the substantial part of this paper. Underlining the challenges and safety issues with high-power chassis, guidelines for designing and constructing a chassis that simulates the real environment of a typical data center are presented.Copyright