Optimality of neighbor-balanced designs for total effects

The purpose of this paper is to study optimality of circular neighbor-balanced block designs when neighbor effects are present in the model. In the literature many optimality results are established for direct effects and neighbor effects separately, but few for total effects, that is, the sum of direct effect of treatment and relevant neighbor effects. We show that circular neighbor-balanced designs are universally optimal for total effects among designs with no self neighbor. Then we give efficiency factors of these designs, and show some situations where a design with self neighbors is preferable to a neighbor-balanced design.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Statistics (http://www.imstat.org/aos/) at http://dx.doi.org/10.1214/00905360400000048

Evaluating Interaction Techniques in an Interactive Workspace: Comparing the Effectiveness of a Textual Interface, Virtual Paths Interface, and ARIS

ARIS is an interface that enables users to visually relocate applications and redirect input among myriad devices in an interactive workspace. While we previously claimed that ARIS is more effective than other interfaces for performing these tasks, this work seeks to empirically validate our claim. We compared the use of ARIS to an interaction design of a text-based and virtual paths interface for relocating applications and redirecting input in an interactive workspace. Results show that (i) users can relocate applications and redirect input faster with ARIS than a text-based interface, (ii) users commit fewer errors with ARIS than a text-based interface, (iii) users experience less workload and are more satisfied with ARIS than a text-based interface, and (iv) ARIS was comparable to the use of a virtual paths interface. ARIS is more effective than an interaction design that requires a user to mentally map and select textual identifiers, while supporting functionality beyond that of a virtual paths interface

A planning practitioner’s reflections on managing complex scheduling challenges

This work represents the reflection-on-action of a planning practitioner from the field of aircraft manufacturing who manages between 40 and 50 planners at any one time and who has influenced the development of many others over the last twenty years. This is an industry of considerable scale and complexity that requires an appropriately positioned planning and scheduling response. From the perspective of the head of planning (Wings), the key impact on the practice reflected upon here is on the integrated positioning of planning into a critical community (a centre of competence), where the roles and the interaction provide an appreciative framework for planners to give of their best. The four core themes explored in this work start with the way of working embedded in an integrated planning approach to enable a route into the wider organisation and how the tasks become clarified in this setting in terms of scope; how a cross-team supportive approach is established; how role gaps are anticipated; and how retaining and using experience is thought about, while reinforcing appreciation through continuous improvement activity and professionally maintaining the pool of planners. An integrated approach then supports the spread, sharing, development, accessibility and application of knowledge in more resourceful and relevant ways than if the approach was task-orientated, boundaried and transactional. This is illustrated by examples of why learning curves matter and how they may be interpreted for impact, and why using governance templates to clearly capture planning outcomes is so important. Examples of tools are given that both support and emerge from an integrated planning approach: cardinal rules, red reports, plan-on-a-page and sign-off packs that can secure a professional planning input. All of the above are positioned in an understanding of how complexity builds up during the phases of a major aircraft development programme, before maturing to the series build phase that follows a launch. This critical engagement places these themes in context within both practice and related literature. These reflections have the potential to enrich the body of knowledge in this field, as the role perspectives currently in the public domain are either based on only one or two launch cycles, at best, or have the limitation of only part of the five to seven years it takes to deliver a new aeroplane, from drawing board to market. This reflection-on–action is based on multiple cycles, giving a wider perspective over a longer time. I propose that this exploration into complex planning has the potential to effect significant change in the professional role of a planning practitioner. It does so through recontextualising the planner’s role as both facilitating articulation between different stakeholders and developing a range of practical products and tools that structure and delineate how this re-conception of the planning role operates in complex environments. Of key importance to this is the value of ongoing critical reflection of the role as a form of leadership, based on indicators of trust being maintained

Fast and deep deformation approximations

Character rigs are procedural systems that compute the shape of an animated character for a given pose. They can be highly complex and must account for bulges, wrinkles, and other aspects of a character's appearance. When comparing film-quality character rigs with those designed for real-time applications, there is typically a substantial and readily apparent difference in the quality of the mesh deformations. Real-time rigs are limited by a computational budget and often trade realism for performance. Rigs for film do not have this same limitation, and character riggers can make the rig as complicated as necessary to achieve realistic deformations. However, increasing the rig complexity slows rig evaluation, and the animators working with it can become less efficient and may experience frustration. In this paper, we present a method to reduce the time required to compute mesh deformations for film-quality rigs, allowing better interactivity during animation authoring and use in real-time games and applications. Our approach learns the deformations from an existing rig by splitting the mesh deformation into linear and nonlinear portions. The linear deformations are computed directly from the transformations of the rig's underlying skeleton. We use deep learning methods to approximate the remaining nonlinear portion. In the examples we show from production rigs used to animate lead characters, our approach reduces the computational time spent on evaluating deformations by a factor of 5×-10×. This significant savings allows us to run the complex, film-quality rigs in real-time even when using a CPU-only implementation on a mobile device

Simulation of Cu-Mg metallic glass: Thermodynamics and Structure

We have obtained effective medium theory (EMT) interatomic potential parameters suitable for studying Cu-Mg metallic glasses. We present thermodynamic and structural results from simulations of such glasses over a range of compositions. We have produced low-temperature configurations by cooling from the melt at as slow a rate as practical, using constant temperature and pressure molecular dynamics. During the cooling process we have carried out thermodynamic analyses based on the temperature dependence of the enthalpy and its derivative, the specific heat, from which the glass transition temperature may be determined. We have also carried out structural analyses using the radial distribution function (RDF) and common neighbor analysis (CNA). Our analysis suggests that the splitting of the second peak, commonly associated with metallic glasses, in fact has little to do with the glass transition itself, but is simply a consequence of the narrowing of peaks associated with structural features present in the liquid state. In fact the splitting temperature for the Cu-Cu RDF is well above $T_g$. The CNA also highlights a strong similarity between the structure of the intermetallic alloys and the amorphous alloys of similar composition. We have also investigated the diffusivity in the supercooled regime. Its temperature dependence indicates fragile-liquid behavior, typical of binary metallic glasses. On the other hand, the relatively low specific heat jump of around $1.5 k_B/\mathrm{at.}$ indicates apparent strong-liquid behavior, but this can be explained by the width of the transition due to the high cooling rates.Comment: 12 pages (revtex, two-column), 12 figures, submitted to Phys. Rev.

Low cost fabrication development for oxide dispersion strengthened alloy vanes

Viable processes were developed for secondary working of oxide dispersion strengthened (ODS) alloys to near-net shapes (NNS) for aircraft turbine vanes. These processes were shown capable of producing required microstructure and properties for vane applications. Material cost savings of 40 to 50% are projected for the NNS process over the current procedures which involve machining from rectangular bar. Additional machining cost savings are projected. Of three secondary working processes evaluated, directional forging and plate bending were determined to be viable NNS processes for ODS vanes. Directional forging was deemed most applicable to high pressure turbine (HPT) vanes with their large thickness variations while plate bending was determined to be most cost effective for low pressure turbine (LPT) vanes because of their limited thickness variations. Since the F101 LPT vane was selected for study in this program, development of plate bending was carried through to establishment of a preliminary process. Preparation of ODS alloy plate for bending was found to be a straight forward process using currently available bar stock, providing that the capability for reheating between roll passes is available. Advanced ODS-NiCrAl and ODS-FeCrAl alloys were utilized on this program. Workability of all alloys was adequate for directional forging and plate bending, but only the ODS-FeCrAl had adequate workability for shaped preform extrustion