Gradient-Based Multi-Component Topology Optimization for Manufacturability

Topology optimization is a method where the distribution of materials within a design domain is optimized for a structural performance. Since the geometry is represented non-parametrically, it facilitates innovative designs through the exploration of arbitrary shapes. Due to its unconstrained exploration, however, topology optimization often generates impractical designs with features that prevent economical manufacturing, e.g., complex perimeters and many holes. Above all, existing topology optimization methods assume that the optimized structure will be made as a single piece. However, structures are usually not monolithic (i.e., single-piece), but assemblies of multiple components, e.g., cars, airplanes, or even chairs. It is mainly because producing multiple components with simple geometries is often less expensive (i.e., better manufacturability) than producing a large single-piece part with complex geometries, even with the additional cost of assembly. This dissertation discussed a topology optimization method for designing structures assembled from components, each built by a certain manufacturing process, termed the MTO. The prior art of MTO used discrete formulations solved by genetic algorithms. To overcome the high computational cost associated with non-gradient heuristic optimization, this dissertation proposed a continuously relaxed gradient-based formulation for MTO. The proposed formulation was demonstrated with three manufacturing processes. For the sheet metal stamping process, by modeling stamping die cost manufacturing constraints and assuming resistant spot welding joints, the simultaneous optimization of base topology and component decomposition was, for the first time, attained using an efficient gradient-based optimization algorithm based on design sensitivities. For the composite manufacturing process, a cube-to-simplex projection and penalization method was proposed to handle the membership unity requirement. With the multi-component concept, a unique structural design solution for economical composite manufacturing was achieved. The component-wise anisotropic material orientation design for topology optimization was presented without prescribing a set of alternative discrete angles as required by most existing material orientation methods. For the additive manufacturing process, the MTO method enabled the design of additively manufactured structures larger than the printer's build volume. By modeling manufacturing constraints on the build volume limit and elimination of enclosed holes, the optimized structure was an assembly of multiple components, each produced by a powder bed additive manufacturing machine. The first reported 3D example of MTO was presented.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145989/1/yuqingz_1.pd

Smooth Infinite Economics

Equilibrium conditions in smooth infinite economies with separable utilities are described by Fredholm maps, which are Frechet differentiable. Therefore, Smale's extension of Sard's theorem can be used to studying infinite economies. We study structural stability and local uniqueness of equilibrium in smooth infinite economies and relate the theory of markets to modern Fredholm theory

Smooth infinite economies

Equilibrium conditions in smooth infinite economies with separable utilities are described by Fredholm maps, which are Frechet differentiable. Therefore, Smale's extension of Sard's theorem can be used to study infinite economies. We study structural stability and local uniqueness of equilibrium in smooth infinite economies and relate the theory of markets to modern Fredholm theory

ERP and ITS Application in Mainland China

Enterprise Resource Planning (ERP) is a good technology for planning and controlling of a manufacturing company. Because of the “Manufacturing Fundamental Equation”, ERP is applicable widely. But, the data foundations of the companies must be accurate and complete for using ERP, and different methods of thinking in management must be needed. For years, the application status of ERP is not as good as we expected in Mainland China. But we believe that the situation will be improved if leaders and staffs of manufacturing companies have the common opinion of holding on to the implementation and application of ERP. ERP is continuously developing. Now, integrating ERP with other management theories and methods is the tren

Over-Confidence and Cycles in Real Estate Markets: Cases in Hong Kong and Asia

Studies on the calibration of subjective probabilities find that people tend to over-estimate the precision of their knowledge. In this paper we develop a semi-rational model and apply it to the real estate markets in Hong Kong and other Asian countries. The key point is that a person is rational about her/his private information until her/his private information is confirmed by a clearly defined market signal. Using a pre-sale as a mechanism of updating a developer's beliefs, this paper analyzes the impact of over-confidence on overbuilding and cycles in real estate markets. Our finding indicates that a pre-sale activity will increase the magnitude of over-building and over-confidence will increase the volatility in real estate markets. Our model also has implications to the well-established literature dealing with the issue of over-capacity in many industrial sectors.

Influence of Helicobacter pylori culture supernatant on the ecological balance of a dual-species oral biofilm

Dental caries is a chronic progressive disease occurring in the tooth hard tissue due to multiple factors, in which bacteria are the initial cause. Both Streptococcus mutans and Streptococcus sanguinis are main members of oral biofilm. Helicobacter pylori may also be detected in dental plaque, playing an important role in the development of dental caries. Objective The aim of this study was to investigate the effect of H. pylori culture supernatant on S. mutans and S. sanguinis dual-species biofilm and to evaluate its potential ability on affecting dental health. Material and methods The effect of H. pylori supernatant on single-species and dual-species biofilm was measured by colony forming units counting and fluorescence in situ hybridization (FISH) assay, respectively. The effect of H. pylori supernatant on S. mutans and S. sanguinis extracellular polysaccharides (EPS) production was measured by both confocal laser scanning microscopy observation and anthrone-sulfuric acid method. The effect of H. pylori supernatant on S. mutans gene expression was measured by quantitative real-time PCR (qRT-PCR) assays. Results H. pylori supernatant could inhibit both S. mutans and S. sanguinis biofilm formation and EPS production. S. sanguinis inhibition rate was significantly higher than that of S. mutans. Finally, S. mutans bacteriocin and acidogenicity related genes expression were affected by H. pylori culture supernatant. Conclusion Our results showed that H. pylori could destroy the balance between S. mutans and S. sanguinis in oral biofilm, creating an advantageous environment for S. mutans, which became the dominant bacteria, promoting the formation and development of dental caries

Financial development, input of public finance and urbanization in China

This paper studies the effects of financial development and input of public finance on urbanization in China. It shows that the input of public finance has an obvious influence on the urbanization, but the financial development does not in the short run, that in the long run there is a relationship of equilibrium among them and the effects of the efficiency of financial development and the input of public finance are obvious, and that the contribution of the financial development to the urbanization is relatively greater in the longer periods