Generating analysis topology using virtual topology operators

AbstractVirtual topology operations have been utilized to generate an analysis topology definition suitable for downstream mesh generation. Detailed descriptions are provided for virtual topology merge and split operations for all topological entities, where virtual decompositions are robustly linked to the underlying geometry. Current virtual topology technology is extended to allow the virtual partitioning of volume cells. A valid description of the topology, including relative orientations, is maintained which enables downstream interrogations to be performed on the analysis topology description, such as determining if a specific meshing strategy can be applied to the virtual volume cells. As the virtual representation is a true non-manifold description of the sub-divided domain the interfaces between cells are recorded automatically. Therefore, the advantages of non-manifold modelling are exploited within the manifold modelling environment of a major commercial CAD system without any adaptation of the underlying CAD model. A hierarchical virtual structure is maintained where virtual entities are merged or partitioned. This has a major benefit over existing solutions as the virtual dependencies here are stored in an open and accessible manner, providing the analyst with the freedom to create, modify and edit the analysis topology in any preferred sequence

Parametric design velocity computation for CAD-based design optimization using adjoint methods

This paper presents an efficient optimization process, where the parameters defining the features in a feature-based CAD model are used as design variables. The process exploits adjoint methods for the computation of gradients, and as such the computational cost is essentially independent of the number of design variables, making it ideal for optimization in large design spaces. The novelty of this paper lies in linking the adjoint surface sensitivity information with geometric sensitivity values, referred to as design velocities, computed for CAD models created in commercial CAD systems (e.g. CATIA V5 or Siemens NX)

Decomposing complex thin-walled CAD models for hexahedral-dominant meshing

AbstractThis paper describes an automatic method for identifying thin-sheet regions (regions with large lateral dimensions relative to the thickness) for complex thin walled components, with a view to using this information to guide the hex meshing process. This fully automated method has been implemented in a commercial CAD system (Siemens NX) and is based on the interrogation and manipulation of face pairs, which are sets of opposing faces bounding thin-sheet regions. Careful consideration is given to the mapping, merging and intersection of face pairs to generate topologies suitable for sweep meshing thin-sheet regions, and for treating the junctions between adjacent thin-sheet regions. The quality of the resulting hexahedral mesh is considered when making decisions on the generation and positioning of the cutting surfaces required to isolate thin-sheet regions. The resulting decomposition delivers a substantial step towards automatic hexahedral meshing for complex thin-walled geometries. It is proposed that hexahedral meshes be applied to the identified thin-sheet regions by quad meshing one of the faces bounding the thin-sheet region and sweeping it through the thickness to create hexahedral elements

Sublingual Immunization with M2-Based Vaccine Induces Broad Protective Immunity against Influenza

The ectodomain of matrix protein 2 (M2e) of influenza A virus is a rationale target antigen candidate for the development of a universal vaccine against influenza as M2e undergoes little sequence variation amongst human influenza A strains. Vaccine-induced M2e-specific antibodies (Abs) have been shown to display significant cross-protective activity in animal models. M2e-based vaccine constructs have been shown to be more protective when administered by the intranasal (i.n.) route than after parenteral injection. However, i.n. administration of vaccines poses rare but serious safety issues associated with retrograde passage of inhaled antigens and adjuvants through the olfactory epithelium. In this study, we examined whether the sublingual (s.l.) route could serve as a safe and effective alternative mucosal delivery route for administering a prototype M2e-based vaccine. The mechanism whereby s.l. immunization with M2e vaccine candidate induces broad protection against infection with different influenza virus subtypes was explored.A recombinant M2 protein with three tandem copies of the M2e (3M2eC) was expressed in Escherichia coli. Parenteral immunizations of mice with 3M2eC induced high levels of M2e-specific serum Abs but failed to provide complete protection against lethal challenge with influenza virus. In contrast, s.l. immunization with 3M2eC was superior for inducing protection in mice. In the latter animals, protection was associated with specific Ab responses in the lungs.The results demonstrate that s.l. immunization with 3M2eC vaccine induced airway mucosal immune responses along with broad cross-protective immunity to influenza. These findings may contribute to the understanding of the M2-based vaccine approach to control epidemic and pandemic influenza infections

Laparoscopic Colorectal Surgery Outcomes Improved After National Training Program (LAPCO) for Specialists in England

OBJECTIVE: To examine the impact of The National Training Programme for Laparoscopic Colorectal Surgery (Lapco) on the rate of laparoscopic surgery and clinical outcomes of cases performed by Lapco surgeons after completion of training.SUMMERY BACKGROUND DATA: Lapco provided competency-based supervised clinical training for specialist colorectal surgeons in England.METHODS: We compared the rate of laparoscopic surgery, mortality and morbidity for colorectal cancer resections by Lapco delegates and non-Lapco surgeons in 3-year periods preceding and following Lapco using difference in differences analysis. The changes in the rate of post-Lapco laparoscopic surgery with the Lapco sign-off competency assessment and in-training global assessment scores were examined using risk-adjusted cumulative sum to determine their predictive clinical validity with predefined competent scores of 3 and 5 respectively.RESULTS: 108 Lapco delegates performed 4586 elective colorectal resections pre-Lapco and 5115 post-Lapco while non-Lapco surgeons performed 72930 matched cases. Lapco delegates had a 37.8% increase in laparoscopic surgery which was greater than non-Lapco surgeons by 20.9% (95% CI, 18.5 to 23.3, p [less than] 0.001) with a relative decrease in 30-day mortality by -1.6% (95% CI, -3.4 to -0.2, p = 0.039) and 90-day mortality by -2.3% (95% CI, -4.3 to -0.4, p = 0.018). The change point of risk-adjusted cumulative sum was 3.12 for competency assessment tool and 4.74 for global assessment score whereas laparoscopic rate increased from 44% to 66% and 40% to 56% respectively.CONCLUSIONS: Lapco increased the rate of laparoscopic colorectal cancer surgery and reduced mortality and morbidity in England. In-training competency assessment tools predicted clinical performance after training

Model for screening of resonant magnetic perturbations by plasma in a realistic tokamak geometry and its impact on divertor strike points

This work addresses the question of the relation between strike-point splitting and magnetic stochasticity at the edge of a poloidally diverted tokamak in the presence of externally imposed magnetic perturbations. More specifically, ad-hoc helical current sheets are introduced in order to mimic a hypothetical screening of the external resonant magnetic perturbations by the plasma. These current sheets, which suppress magnetic islands, are found to reduce the amount of splitting expected at the target, which suggests that screening effects should be observable experimentally. Multiple screening current sheets reinforce each other, i.e. less current relative to the case of only one current sheet is required to screen the perturbation.Comment: Accepted in the Proceedings of the 19th International Conference on Plasma Surface Interactions, to be published in Journal of Nuclear Materials. Version 2: minor formatting and text improvements, more results mentioned in the conclusion and abstrac