Significance: Percutaneous valve replacement procedures enable the deployment of bioprosthetic heart valves through a catheter, which offers a minimally invasive option to treat valvular heart disease. Although these bioprostheses typically employ thinner leaflet tissues to accommodate the collapsed valve dimensions, the impact of using such tissues remains poorly understood. This study used high-fidelity computational methods to model realistic aortic valve implants and analyze the behavior of thinner tissues in the valvular system. The results from this investigation provide essential knowledge about a previously understudied phenomenon and indicate that thinner, more flexible biological tissues induce significant leaflet flutter during the cardiac cycle. This observed response introduces blood flow disturbances and leaflet irregularities that can lead to cardiovascular dysfunction and reduced valve durability.

This work couples high-fidelity moving-domain finite element compressible flow modeling with a Surrogate Management Framework (SMF) for optimization to effectively design a variable speed gas turbine stage. The superior accuracy of high-fidelity modeling, however, comes with relatively high computational costs, which are further amplified in the iterative design process that relies on parametric sweeps. An innovative approach is developed to reduce the number of iterations needed for optimal design, leading to a significant reduction in the computational cost without sacrificing the high fidelity of the analysis. The proposed design optimization approach is applied to a novel incidence-tolerant turbomachinery blade technology that articulates the stator- and rotor-blade positions of an annular single-stage high pressure turbine to achieve peak performance. This work also extends our understanding of rotor–stator interactions by simulating complex internal flows occurring during multi-speed turbine operation. Potential variable-speed gas turbine stage designs and the proposed optimization approach are presented to provide valuable insight into this new turbomachinery technology that can positively impact future propulsion systems.

This paper is about project risk management. In the project environment, risk management is an effective and prevailing method to deal with project uncertainties. However, it is far from being a panacea. Worse, risk management is filled with pitfalls that we must be aware of and avoid. Otherwise, the process won't help much, on the contrary, significant waste of resources and opportunities could result. Categorically there are three types of risks that we normally face in a project. The first two types of risks are known unknowns. Once they are identified, they can be managed. The third kind is due to human errors, which are often hidden and undetectable until they become crises. Though human errors can be deadly, since they are man-made, they are avoidable. In project risk management, we must do all the five steps right to be effective. At ITRI we have been successful