Implicit upper bound error estimates for combined expansive model and discretization adaptivity

A computational methodology for goal-oriented combined discretization and expansive (refined) model adaptivity by overall implicit error control of quantities of interest is presented, requiring estimators of primal and dual discretization and model errors. In the case of dimensional within model adaptivity, prolongations of coarse model solutions into the solution space of a fine model for defining a consistent model error are necessary, which can be achieved at the element level by two strategies. The first one is an orthogonalized kinematic prolongation of nodal displacements, whereas the second one uses prolongations of the external loads which are then used to solve additional local variational problems thus yielding prolongated solutions which a priori fulfill the required orthogonality relations at the element level. Finally, a numerical example of an elastic continuous T-beam is presented with comparative results where goal-oriented error estimation is applied to linear elasticity with a $2\frac{1}{2}\text{D}$ discrete Reissner–Mindlin plate model as the coarse model and the 3D theory as the fine model.     

Ranking software components for reuse based on non-functional properties

One of the biggest obstacles to software reuse is the cost involved in evaluating the suitability of possible reusable components. In recent years, code search engines have made significant progress in establishing the semantic suitability of components for new usage scenarios, but the problem of ranking components according to their non-functional suitability has largely been neglected. The main difficulty is that a component’s non-functional suitability for a specific reuse scenario is usually influenced by multiple, “soft” criteria, but the relative weighting of metrics for these criteria is rarely known quantitatively. What is required, therefore, is an effective and reliable strategy for ranking software components based on their non-functional properties without requiring users to provide quantitative weighting information. In this paper we present a novel approach for achieving this based on the non-dominated sorting of components driven by a specification of the relative importance of non-functional properties as a partial ordering. After describing the ranking algorithm and its implementation in a component search engine, we provide an explorative study of its properties on a sample set of components harvested from Maven Central.     

Towards improved benchmarking of black-box optimization algorithms using clustering problems

The field of Metaheuristics has produced a large number of algorithms for continuous, black-box optimization. In contrast, there are few standard benchmark problem sets, limiting our ability to gain insight into the empirical performance of these algorithms. Clustering problems have been used many times in the literature to evaluate optimization algorithms. However, much of this work has occurred independently on different problem instances and the various experimental methodologies used have produced results which are frequently incomparable and provide little knowledge regarding the difficulty of the problems used, or any platform for comparing and evaluating the performance of algorithms. This paper discusses sum of squares clustering problems from the optimization viewpoint. Properties of the fitness landscape are analysed and it is proposed that these problems are highly suitable for algorithm benchmarking. A set of 27 problem instances (from 4-D to 40-D), based on three well-known datasets, is specified. Baseline experimental results are presented for the Covariance Matrix Adaptation-Evolution Strategy and several other standard algorithms. A web-repository has also been created for this problem set to facilitate future use for algorithm evaluation and comparison.     

Temperature Uniformity Optimization for a silicon implant anneal into GaAs using Opus ™ simulation software

Opus ^™, which stands for “Optimized Uniformity Simulator”, has been described in the literature as a powerful tool to assist in the optimization of temperature uniformity in the STEAG Electronic Systems series of rapid thermal processors. Historically, this tool has been used extensively for a variety of silicon processing. With this simulation, the temperature uniformity of 100 mm Si₃N₄ encapsulated GaAs with a dual silicon implant anneal at 847°C, 40 s was optimized to <2°C across the wafer. Ramp rates ≤20°C/s were obtained without slip.     

Expressibility of output equals input

We examine the common and seemingly simple specification that the output stream equals the input stream. We show that this is not in full generality expressible in first-order or temporal logic by an infinite set of sentences or a recursive specification, but requires certain extra assumptions, such as the existence of a clock or discrete input values.The main negative results are stated for first-order expressibility and have direct corollaries for inexpressibility in first-order temporal logic: output equals input with arbitrary delay is not expressible by a (perhaps infinite) theory (Theorems 2 and 3), even with a timestamp (Theorem 8), and is not expressible for an timeline by a sentence, even with a timestamp (Theorem 10). Output equals input with constant delay cannot be expressed for timeline by a sentence with extra unary predicates over the timeline.As an example of the positive results, we show output equals input can be expressed by a sentence in the language with a (weak) clock if the base model contains either an extra function (Theorem 14), or arithmetic (Theorem 15).Supported by Aerospace Sponsored Research     

Discrimination between Bacillus species by impedance analysis of individual dielectrophoretically positioned spores

We combine the use of dielectrophoretic positioning with electrical impedance measurements to detect and discriminate between individual bacterial spores on the basis of their electrical response. Using lithographically defined microelectrodes, we use dielectrophoresis to manipulate individual bacterial spores between the electrodes. The introduction of a single spore between the microelectrodes produces a significant change in electrical response that is species-dependent. When positioned between two electrodes and an AC voltage was applied, single spores caused current increases averaging 6.8 (+/-2.4) pA for Bacillus mycoides to 1.18 (+/-0.37) pA for Bacillus licheniformis. Using a mixture of spores of two different species, we demonstrate the ability to distinguish the species of individual spores in real time. This work demonstrates the feasibility of using impedance measurements for real-time detection and discrimination between different types of spores.     

Computer generated holograms from three dimensional meshes using an analytic light transport model

We present a method to analytically compute the light distribution of triangles directly in frequency space. This allows for fast evaluation, shading, and propagation of light from 3D mesh objects using angular spectrum methods. The algorithm complexity is only dependent on the hologram resolution and the polygon count of the 3D model. In contrast to other polygon based computer generated holography methods we do not need to perform a Fourier transform per surface. The theory behind the approach is derived, and a suitable algorithm to compute a digital hologram from a general triangle mesh is presented. We review some first results rendered on a spatial-light-modulator-based display by our proof-of-concept software.     

Mediators of physical activity behavior change: A multivariate approach.

Objective: Using a multivariate extension of the Baron and Kenny (1986) mediation framework, we examined the simultaneous effect of variables hypothesized to mediate the relationship between a motivationally tailored physical activity intervention, and 6-month physical activity behavior in 239 healthy, underactive adults (M age = 47.5; 82% women). Design: Participants were randomly assigned to (a) print-based feedback; (b) telephone-based feedback; or (c) contact control. Main Outcome Measures: Psychosocial variables, including self-efficacy, decisional balance, and processes of change. Results: All mediation criteria were satisfied for both intervention arms. A moderate indirect effect of print (0.39, 95% CI = 0.21, 0.57) was found due to increases in behavioral processes (0.54, 95% CI = 0.29, 0.80) being attenuated by decreases due to cognitive processes (-0.17, 95%CI = 0.31,-.03). A moderate indirect effect was observed for telephone (0.47, 95% CI = 0.28, 0.66), with increases due to behavioral processes (0.61, 95% CI = 0.34, 0.87) attenuated by decreases due to cognitive processes (0.15, 95% CI = -0.27, -0.02); self-efficacy and decisional balance mediational paths did not attain statistical significance. Conclusions: These findings highlight the importance of studies that deconstruct the theoretical components of interventions to determine which combination produces the greatest behavior changes at the lowest cost. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electric field and tip geometry effects on dielectrophoretic growth of carbon nanotube nanofibrils on scanning probes

Single-wall carbon nanotube (SWNT) nanofibrils were assembled onto a variety of conductive scanning probes including atomic force microscope (AFM) tips and scanning tunnelling microscope (STM) needles using positive dielectrophoresis (DEP). The magnitude of the applied electric field was varied in the range of 1-20?V to investigate its effect on the dimensions of the assembled SWNT nanofibrils. Both length and diameter grew asymptotically as voltage increased from 5 to 18?V. Below 4?V, stable attachment of SWNT nanofibrils could not be achieved due to the relatively weak DEP force versus Brownian motion. At voltages of 20?V and higher, low quality nanofibrils resulted from incorporating large amounts of impurities. For intermediate voltages, optimal nanofibrils were achieved, though pivotal to this assembly is the wetting behaviour upon tip immersion in the SWNT suspension drop. This process was monitored in situ to correlate wetting angle and probe geometry (cone angles and tip height), revealing that probes with narrow cone angles and long shanks are optimal. It is proposed that this results from less wetting of the probe apex, and therefore reduces capillary forces and especially force transients during the nanofibril drawing process. Relatively rigid probes (force constant ≥2?N?m(-1)) exhibited no perceivable cantilever bending upon wetting and de-wetting, resulting in the most stable process control.