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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 69 (2004), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : A group of selected enzymes were subjected to continuous pulsed electric field (PEF) treatments to evaluate the inactivation effect of PEF. For a treatment time of 126 μs, 51.7% and 83.8% of pepsin was inactivated at 37.0 kV/cm and 41.8 kV/cm, respectively. Enzyme activity of polyphenol oxidase decreased 38.2% when treated at 33.6 kV/cm for 126 μs. Enzyme activity decreased 18.1% and 4.0% for peroxidase treated at 34.9 kV/cm and chymotrypsin treated at 34.2 kV/cm, respectively. No significant change in lysozyme activity was observed after PEF from 0 to 38 kV/cm for 126 μs. Both PEF and the induced heat contributed to the observed inactivation effect, depending on the properties of enzymes and test conditions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 9 (1995), S. 245-249 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Topology optimization is used for obtaining the best layout of vehicle structural components to achieve predetermined performance goals. An in-house topology optimization software, TOP, has been developed to analyse important automotive components. The topology design problem is formulated as a general optimization problem and is solved by the mathematical programming method. The MSC/NASTRAN finite element code is employed for response analyses. The use of MSC/NASTRAN is significant, because it not only allows engineers to use a wellaccepted and widely-used finite element code with no size limit on the model, but also permits developers to concentrate on the rest of the topology optimization program. Three automotive examples including a simplified truck frame, a deck lid, and a space frame structure are presented.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 10 (1995), S. 128-136 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This research integrates component mode synthesis with a multilevel design optimization strategy to develop a design methodology for making the dynamical modification of complex structures simpler and tractable. The component mode synthesis formulates the eigenvalue equation of the entire structure in terms of vibration characteristics of local structure components. With this particular feature, the component mode synthesis helps to facilitate a two-stage procedure for the dynamic modification of a complex structure; the lower-level design optimization modifies the local structure components whose performances are prescribed by the optimal solution of the upper-level design optimization. The paper first discusses the formulation and the derivation of the Kuhn-Tucker necessary conditions for the proposed design optimization procedure and then presents numerical examples to demonstrate its numerical implementation and applicability.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 12 (1996), S. 98-105 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Previous research on topology optimization focussed primarily on global structural behaviour such as stiffness and frequencies. However, to obtain a true optimum design of a vehicle structure, stresses must be considered. The major difficulties in stress based topology optimization problems are two-fold. First, a large number of constraints must be considered, since unlike stiffness, stress is a local quantity. This problem increases the computational complexity of both the optimization and sensitivity analysis associated with the conventional topology optimization problem. The other difficulty is that since stress is highly nonlinear with respect to design variables, the move limit is essential for convergence in the optimization process. In this research, global stress functions are used to approximate local stresses. The density method is employed for solving the topology optimization problems. Three numerical examples are used for this investigation. The results show that a minimum stress design can be achieved and that a maximum stiffness design is not necessarily equivalent to a minimum stress design.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 12 (1996), S. 217-221 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Plane sheet panels exhibit poor stiffness and NVH (noise, vibration, and harshness) performance due to their flexibility. A common and cost-effective approach in the automotive industry to improve the stiffness and NVH peformance of sheet panels is the addition of beads. However, no systematic methodology is available for determining the optimal pattern of beads in sheet metal. This research explores the feasibility of applying topology optimization methods to the bead design of sheet panels. The approach starts with adding beam elements to the shell element model of the sheet panel to simulate the stiffness improvement of the structure and then uses the topology optimization method to obtain the optimal layout of the beam elements. A cantilever plate is used to perform a preliminary study for bead pattern design and a simplified vehicle structure is used to demonstrate the applicability of the proposed method.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 17 (1999), S. 140-146 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In many engineering structures, failure occurs either at the connection itself or in the component at the point of attachment of the connection. To extend the service life of the structure it is important to ensure that the loads borne by the connections are distributed as uniformly as possible. This would also minimize the possibility of localized high stress regions within the component. In this work a topology optimization based approach has been developed to incorporate fastener load constraints into a problem formulated for optimal location of fasteners. The computational results indicate that it is effective in reducing the maximum fastener loads without compromising on the overall stiffness of the structure.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 5 (1992), S. 55-63 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Component shape optimization normally requires a parameterized geometric representation or a generic model for the solid geometry which evolves to an optimal design. Generic models for large-scale three-dimensional components are difficult to build. The difficulties result from the lack of robust automatic mesh generation and the availability of a parametric model. To remedy this problem, a basis function concept used in mathematics for representing an arbitrary function is employed for geometric representation of solids. This approach does not require automatic mesh generation or parametric models for geometric representation and thus is suitable for large-scale complicated components. Numerical examples are used to demonstrate the applicability of this approach to realistic problems.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 5 (1993), S. 233-239 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An engine exhaust manifold made of cast iron cracks during thermal shock testing. The test process is simulated by finite element analysis. The manifold is formulated as a linear heat transfer and thermoelasticity problem in a variational form. Analytical expressions for shape design sensitivities of general three-dimensional problems are presented, using the material derivative approach. A hybrid approach is described and used during the optimization process. This approach takes advantage of the direct and the adjoint variable methods and is the most efficient in calculating the sensitivity of the structural responses. After the finite element model is verified by comparing the results with those from testing, the engine exhaust manifold is optimized with respect to its geometry.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 22 (1996), S. 1135-1147 
    ISSN: 0271-2091
    Keywords: Navier-Stokes equations ; Taylor-Couette flow ; multiple solutions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new numerical procedure for predicting multiple solutions of Taylor vortices in a spherical gap is presented. The steady incompressible Navier-Stokes equations in primitive variables are solved by a finite- difference method using a matrix preconditioning technique. Routes leading to multiple flow states are designed heuristically by imposing symmetric properties. Both symmetric and asymmetric solutions can be predicted in a deterministic way. The current procedure gives very fast convergence rate to the desired flow modes. This procedure provides an alternative way of finding all possible stable steady axisymmetric flow modes.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 8 (1988), S. 1241-1268 
    ISSN: 0271-2091
    Keywords: Incompressible flow ; Navier-Stokes equations ; Finite differences ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper discusses incompressible Navier-Stokes solution methods with an emphasis on the pseudocompressibility method. A steady-state flow solver based on the pseudocompressibility approach is then described. This flow solver code has been used to analyse the internal flow in the Space Shuttle main engine hot-gas manifold. Salient features associated with this three-dimensional realistic flow simulation are discussed. Numerical solutions relevant to the current engine analysis and the redesign effort are discussed along with experimental results. This example demonstrates the potential of computational fluid dynamics as a design tool for aerospace applications.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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