21,866 research outputs found
Polynomial Response Surface Approximations for the Multidisciplinary Design Optimization of a High Speed Civil Transport
Surrogate functions have become an important tool in multidisciplinary design optimization to deal with noisy functions, high computational cost, and the practical difficulty of integrating legacy disciplinary computer codes. A combination of mathematical, statistical, and engineering techniques, well known in other contexts, have made polynomial surrogate functions viable for MDO. Despite the obvious limitations imposed by sparse high fidelity data in high dimensions and the locality of low order polynomial approximations, the success of the panoply of techniques based on polynomial response surface approximations for MDO shows that the implementation details are more important than the underlying approximation method (polynomial, spline, DACE, kernel regression, etc.). This paper surveys some of the ancillary techniques—statistics, global search, parallel computing, variable complexity modeling—that augment the construction and use of polynomial surrogates
Optical spectroscopy of gan microcavities with thicknesses controlled using a plasma etch-back
The effect of an etch-back step to control the cavity length within GaN-based microcavities formed between two dielectric Bragg mirrors was investigated using photoluminescence and reflectivity. The structures are fabricated using a combination of a laser lift-off technique to separate epitaxial III-N layers from their sapphire substrates and electron-beam evaporation to deposit silica/zirconia multilayer mirrors. The photoluminescence measurements reveal cavity modes from both etched and nonetched microcavities. Similar cavity finesses are measured for 2.0 and 0.8 mm GaN cavities fabricated from the same wafer, indicating that the etchback has had little effect on the microcavity quality. For InGaN quantum well samples the etchback is shown to allow controllable reduction of the cavity length. Two etch steps of 100 nm are demonstrated with an accuracy of approximately 5%. The etchback, achieved using inductively coupled plasma and wet chemical etching, allows removal of the low-quality GaN nucleation layer, control of the cavity length, and modification of the surface resulting from lift-off
Exploring Practical Potentials of Business Simulation Games
With the emergence of the digital generation, advances in technology, and the trend towards more experiential learning formats, business simulation games (BSGs) are increasingly used by educators today. Of interest in this paper is the extent to which serious game playing, for business and technology professionals, influences work behaviors in practice. This study explores the business professional’s sense-making process when consciously reasoning about how BSG learning influences business practice. We adapt Toulmin’s framework for deconstructing practical reasoning to capture, analyze, and elicit patterns within arguments made regarding the application of BSG learning to business practice. The findings contribute to theories related to BSGs, and thus would benefit those practitioners who use BSGs
Self-consistent theory of turbulent transport in the solar tachocline. III. Gravity waves
To understand the fundamental physical processes important for the evolution
of solar rotation and distribution of chemical species, we provide theoretical
predictions for particle mixing and momentum transport in the stably stratified
tachocline. By envisioning that turbulence is driven externally in the
tachocline (e.g. by plume penetration), we compute the amplitude of turbulent
flow, turbulent particle diffusivities, and eddy viscosity, by incorporating
the effect of a strong radial differential rotation and stable stratification.
We identify the different roles that the shear flow and stable stratification
play in turbulence regulation and transport. Particle transport is found to be
severely quenched due to stable stratification as well as radial differential
rotation, especially in the radial direction with an effectively more efficient
horizontal transport. The eddy viscosity is shown to become negative for
parameter values typical of the tachocline, suggesting that turbulence in the
stably stratified tachocline leads to a non-uniform radial differential
rotation. Similar results also hold in the radiative interiors of stars, in
general
Using evaluation techniques and performance claims to demonstrate public relations impact: An Australian perspective
Public relations professionals use many methods to demonstrate their contribution to organizational goals, yet it is unclear how their attitudes towards evaluation and the reporting of success matches real outcomes. Ten years after the International Public Relations Association produced an evaluation gold paper, this study combines research on Australian practitioners’ evaluation practices and attitudes, and data from industry awards to identify how practitioners demonstrate their accountability. Data suggest that despite the attention paid to evaluation by the academy and industry, practitioners still focus on measuring outputs, not outcomes to demonstrate performance and continue to rely heavily on media-based evaluation methods
Crystal structure of a Fanconi anemia-associated nuclease homolog bound to 5′ flap DNA: basis of interstrand cross-link repair by FAN1
Fanconi anemia (FA) is an autosomal recessive genetic disorder caused by defects in any of 15 FA genes responsible for processing DNA interstrand cross-links (ICLs). The ultimate outcome of the FA pathway is resolution of cross-links, which requires structure-selective nucleases. FA-associated nuclease 1 (FAN1) is believed to be recruited to lesions by a monoubiquitinated FANCI–FANCD2 (ID) complex and participates in ICL repair. Here, we determined the crystal structure of Pseudomonas aeruginosa FAN1 (PaFAN1) lacking the UBZ (ubiquitin-binding zinc) domain in complex with 5′ flap DNA. All four domains of the right-hand-shaped PaFAN1 are involved in DNA recognition, with each domain playing a specific role in bending DNA at the nick. The six-helix bundle that binds the junction connects to the catalytic viral replication and repair (VRR) nuclease (VRR nuc) domain, enabling FAN1 to incise the scissile phosphate a few bases distant from the junction. The six-helix bundle also inhibits the cleavage of intact Holliday junctions. PaFAN1 shares several conserved features with other flap structure-selective nucleases despite structural differences. A clamping motion of the domains around the wedge helix, which acts as a pivot, facilitates nucleolytic cleavage. The PaFAN1 structure provides insights into how archaeal Holliday junction resolvases evolved to incise 5′ flap substrates and how FAN1 integrates with the FA complex to participate in ICL repair
Intersection Democracy for Winding Branes and Stabilization of Extra Dimensions
We show that, in the context of pure Einstein gravity, a democratic principle
for intersection possibilities of branes winding around extra dimensions in a
given partitioning yield stabilization, while what the observed space follows
is matter-like dust evolution . Here democracy is used in the sense that, in a
given decimation of extra dimensions, all possible wrappings and hence all
possible intersections are allowed. Generally, the necessary and sufficient
condition for this is that the dimensionality of the observed space
dimensions obey 3\leqm \le N where is the decimation order of the extra
dimensions.Comment: Added a section for linear and non-linear stability analysis of the
equilibrium point. Added references. Corrected typo
Flow in Business Simulation Games: Comparison between Online and Face-to-Face MBA
This study explores the role of flow and its relationship with other elements of Business Simulation Games (BSGs) used in different MBA course delivery methods, namely online vs. face-to-face (F2F). We collect level of flow and other game behavioral variables from young professionals enrolled in an MBA Technology and Operations Management course. We analyze the data with one-way ANOVA to explore flow measures across different course delivery methods. The findings show there exist differences in flow level and performance measures between online and F2F formats
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