Conceptual robustness in simultaneous engineering: An extension of Taguchi's parameter design

Simultaneous engineering processes involve multifunctional teams; team members simultaneously make decisions about many parts of the product-production system and aspects of the product life cycle. This paper argues that such simultaneous distributed decisions should be based on communications about sets of possibilities rather than single solutions. By extending Taguchi's parameter design concepts, we develop a robust and distributed decision-making procedure based on such communications. The procedure shows how a member of a design team can make appropriate decisions based on incomplete information from the other members of the team. More specifically, it (1) treats variations among the designs considered by other members of the design team as conceptual noise; (2) shows how to incorporate such noises into decisions that are robust against these variations; (3) describes a method for using the same data to provide preference information back to the other team members; and (4) provides a procedure for determining whether to release the conceptually robust design or to wait for further decisions by others. The method is demonstrated by part of a distributed design process for a rotary CNC milling machine. While Taguchi's approach is used as a starting point because it is widely known, these results can be generalized to use other robust decision techniques.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45879/1/163_2005_Article_BF01608400.pd

Tolerance optimization using genetic algorithm and approximated simulation.

The purpose of this research is the development of a new approach to tolerance optimization problems. Optimal tolerance allotment problems can be formulated as stochastic optimization problems. Most schemes to solve the stochastic optimization problems have been found to exhibit difficulties in multivariate integration of the probability density function. As a typical example of stochastic optimization, the optimal tolerance allotment problem has the same difficulties. In this research, a new approach based on existing tools was posed. Approximate Monte Carlo simulation and a genetic algorithm were used as analysis (i.e. multivariate integration) and synthesis (i.e. optimization) tools respectively. The new algorithm performed robustly for an extremely approximate simulation. A significant reduction in optimal cost was observed compared to the results obtained in previous studies. After solving the optimal tolerance allotment problem, other types of tolerancing problems (design centering and design centering-tolerance allotment) were considered using similar approaches. An original problem type, the design centering-tolerance allotment (DCTA) problem, was posed and solved with a remarkable cost reduction compared to conventional problem formulations.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103258/1/9308375.pdfDescription of 9308375.pdf : Restricted to UM users only

Set-based design systems for stampings and flexible fixture workspaces.

This thesis describes the development and test of two computational systems for supporting set-based concurrent engineering. They address two problems: (1) to formally represent and manipulate sets of shapes and (2) to automatically synthesize flexible fixture workspaces for a set of stampings. First, there are two approaches to designing products. One is to determine one design quickly and then make iterative changes to it. The other is to define a set of design alternatives in the beginning and to narrow the set as design proceeds. For example, Toyota informally employs the second approach by using many scaled clay models for exploring a design space, design tolerances for representing uncertainties, and lessons-learned books for representing manufacturable shapes. However, Toyota's informal approach relies on humans to imagine and interpret design spaces, and therefore it is inefficient and can cause misunderstandings. Thus, this thesis presents a set-based design system for shapes that enables product development team members to formally represent and manipulate sets of shapes using a computer. This system has been applied to designing stampings, and evaluated to be capable of representing most manufacturing requirements in stamping design handbooks. Second, fixtures are used to position and hold stampings for assembly. These fixtures conventionally have been dedicated and therefore they must be replaced whenever there are model changes. In recent years, however, auto companies increasingly use flexible fixtures, which are composed of robots as programmable fixture elements so that they can be reprogrammed for different stampings rather than being replaced. When designing flexible fixtures, fixture designers must be concerned with not only fixturing of one stamping but also fixture workspaces for a set of stampings. However, existing fixture design methods address fixturing of one stamping only. Thus this thesis presents a system to synthesize flexible fixture workspaces for a set of stampings. Based on circular workspaces for flexible fixture robots, this system finds optimal robot workspaces and their centers on the fixture plate and provides a graphical display for visual checking. This system has been tested with lab data and is effective because of its simplicity and short run time.Ph.D.Applied SciencesIndustrial engineeringMechanical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/129868/2/9635549.pd

Characteristics and phylogenetic analysis of the complete mitochondrial genome of Microstomus achne

Microstomus achne (Jordan and Starks, 1904) is an economically valuable flatfish belonging to the family Pleuronectidae and the only flatfish that inhabits Korea. Here, we report on the complete mitochondrial genome of M. achne and the phylogenetic relationship between close species. The mitogenome is 16,971 bp long and encodes 13 protein-coding genes (PCGs), 22 transfer RNAs, and two ribosomal RNAs. The phylogenetic analysis showed that M. achne clustered with Glyptocephalus stelleri, which supports the conclusion that M. achne belongs to the family Pleuronectidae. The results of this study provide a better understanding of M. achne