Implications of additive manufacturing on complexity management within supply chains in a production environment.

This dissertation focuses on developing a generic framework for using additive manufacturing as an appropriate production method to address the management of complexity in supply chains. While several drivers such as changing customer demand patterns and intensifying global competition increase product complexity, the available number of product variants and related processes within the supply chain itself increase costs and dilute scale effects. Several concepts and tools like mass customization, modularization, and product platforms have been developed in the past decades, but most of them focus on the product structure. Currently, there is no comprehensive tool set developed in the field of complexity management that incorporates all aspects of supply chain performance (costs, service, quality, and lead time) and evaluates the impacts of additive manufacturing to manage the complexity in the supply chain. This dissertation was developed primarily to address this research gap. The literature review in this dissertation provides in-depth reviews on specific topics in the field of additive manufacturing production technology, supply chain management, complexity management, and complexity management in supply chains through additive manufacturing. The dissertation presents the development of a framework for supply chain performance and complexity measurement with a focus on costs and performance depending on production technology. This framework will be the basis for measuring the impacts of additive manufacturing on supply chain performance and level of complexity, by using modeling and reconfiguring supply chain models, and applying complexity management tools in conjunction with additive manufacturing. Based on the findings, a generic framework is developed to identify when and how to apply additive manufacturing to enhance complexity management capabilities in supply chains. Two case studies will be used to show an application field, where additive manufacturing would require additional time, while another case study suggests the usage of additive manufacturing in the context of supply chain complexity: A case study of a control panel supply chain will provide an overview of the implications of substituting an injection molding production technology with an additive manufacturing technology on the supply chain and its complexity. Another case study of teeth aligners shows how additive manufacturing helps to improve supply chain complexity by substituting plaster tools with an additive manufacturing technology

Multipartite Nonlocal Quantum Correlations Resistant to Imperfections

We use techniques for lower bounds on communication to derive necessary conditions in terms of detector efficiency or amount of super-luminal communication for being able to reproduce with classical local hidden-variable theories the quantum correlations occurring in EPR-type experiments in the presence of noise. We apply our method to an example involving n parties sharing a GHZ-type state on which they carry out measurements and show that for local-hidden variable theories, the amount of super-luminal classical communication c and the detector efficiency eta are constrained by eta 2^(-c/n) = O(n^(-1/6)) even for constant general error probability epsilon = O(1)

Completeness of classical spin models and universal quantum computation

We study mappings between distinct classical spin systems that leave the partition function invariant. As recently shown in [Phys. Rev. Lett. 100, 110501 (2008)], the partition function of the 2D square lattice Ising model in the presence of an inhomogeneous magnetic field, can specialize to the partition function of any Ising system on an arbitrary graph. In this sense the 2D Ising model is said to be "complete". However, in order to obtain the above result, the coupling strengths on the 2D lattice must assume complex values, and thus do not allow for a physical interpretation. Here we show how a complete model with real -and, hence, "physical"- couplings can be obtained if the 3D Ising model is considered. We furthermore show how to map general q-state systems with possibly many-body interactions to the 2D Ising model with complex parameters, and give completeness results for these models with real parameters. We also demonstrate that the computational overhead in these constructions is in all relevant cases polynomial. These results are proved by invoking a recently found cross-connection between statistical mechanics and quantum information theory, where partition functions are expressed as quantum mechanical amplitudes. Within this framework, there exists a natural correspondence between many-body quantum states that allow universal quantum computation via local measurements only, and complete classical spin systems.Comment: 43 pages, 28 figure

The Measurement Calculus

Measurement-based quantum computation has emerged from the physics community as a new approach to quantum computation where the notion of measurement is the main driving force of computation. This is in contrast with the more traditional circuit model which is based on unitary operations. Among measurement-based quantum computation methods, the recently introduced one-way quantum computer stands out as fundamental. We develop a rigorous mathematical model underlying the one-way quantum computer and present a concrete syntax and operational semantics for programs, which we call patterns, and an algebra of these patterns derived from a denotational semantics. More importantly, we present a calculus for reasoning locally and compositionally about these patterns. We present a rewrite theory and prove a general standardization theorem which allows all patterns to be put in a semantically equivalent standard form. Standardization has far-reaching consequences: a new physical architecture based on performing all the entanglement in the beginning, parallelization by exposing the dependency structure of measurements and expressiveness theorems. Furthermore we formalize several other measurement-based models: Teleportation, Phase and Pauli models and present compositional embeddings of them into and from the one-way model. This allows us to transfer all the theory we develop for the one-way model to these models. This shows that the framework we have developed has a general impact on measurement-based computation and is not just particular to the one-way quantum computer.Comment: 46 pages, 2 figures, Replacement of quant-ph/0412135v1, the new version also include formalization of several other measurement-based models: Teleportation, Phase and Pauli models and present compositional embeddings of them into and from the one-way model. To appear in Journal of AC