GPU Accelerated Discontinuous Galerkin Methods for Shallow Water Equations

We discuss the development, verification, and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water equations. The shallow water equations are hyperbolic partial differential equations and are widely used in the simulation of tsunami wave propagations. Our algorithms are tailored to take advantage of the single instruction multiple data (SIMD) architecture of graphic processing units. The time integration is accelerated by local time stepping based on a multi-rate Adams-Bashforth scheme. A total variational bounded limiter is adopted for nonlinear stability of the numerical scheme. This limiter is coupled with a mass and momentum conserving positivity preserving limiter for the special treatment of a dry or partially wet element in the triangulation. Accuracy, robustness and performance are demonstrated with the aid of test cases. We compare the performance of the kernels expressed in a portable threading language OCCA, when cross compiled with OpenCL, CUDA, and OpenMP at runtime.Comment: 26 pages, 51 figure

Systematic innovation and the underlying principles behind TRIZ and TOC

Innovative developments in the design of product and manufacturing systems are often marked by simplicity, at least in retrospect, that has previously been shrouded by restrictive mental models or limited knowledge transfer. These innovative developments are often associated with the breaking of long established trade-off compromises, as in the paradigm shift associated with JIT & TQM, or the resolution of design contradictions, as in the case of the dual cyclone vacuum cleaner. The rate of change in technology and the commercial environment suggests the opportunity for innovative developments is accelerating, but what systematic support is there to guide this innovation process. This paper brings together two parallel, but independent theories on inventive problem solving; one in mechanical engineering, namely the Russian Theory of Inventive Problem Solving (TRIZ) and the other originating in manufacturing management as the Theory of Constraints (TOC). The term systematic innovation is used to describe the use of common underlying principles within these two approaches. The paper focuses on the significance of trade-off contradictions to innovation in these two fields and explores their relationship with manufacturing strategy development

Diet, Exercise, Self-Monitoring, Technology, and Motivational Interviewing for Weight Loss in Adults

Obesity, an epidemic in the United States (US), affected 42.4% of adults as of 2017-2018 (Hales, 2020). Comorbidities associated with obesity, such as cardiovascular disease, cancer, and diabetes (Orringer et al., 2020), are some of the leading causes of death in the US (Kochanek et al., 2020). The purpose of this evidence-based practice (EBP) project was to answer the following PICOT question: In adult patients aged 19 years or older who are considered overweight or obese as measured by body mass index (BMI) of ≥ 25 kg/m2 (P), how effective is diet and exercise combined with self-monitoring, a phone application, motivational interviewing (MI) and feedback (I) compared to standard care (C) at lowering BMI (O) over a 12-week period (T)? Adult participants (n = 38) were recruited from an underserved clinic in Northwest Indiana. Participants were provided with educational materials and instructions for downloading a free phone application, following a low-fat and low sugar diet, engaging in at least 30 minutes of walking five times weekly, recording meal choices and exercise amounts, and to participate in biweekly MI phone calls over 12 weeks. An independent-samples t-test was calculated comparing the mean difference in weight and BMI pre and post intervention in the intervention group participants who completed the program (n = 19) to the mean difference in pre and post weight and BMI of participants in the comparison group (n = 14). No significant difference was found (t (31) = 1.575, p \u3e .05) (t (31) = .869, p \u3e .05). The mean difference in weight and BMI for the intervention group (M = 3.10; SD = 5.92) (M = .32; SD = 1.12) was not significantly different from the mean difference in weight and BMI for the comparison group (M = .14; SD = 4.40) (M = 0.2; SD = .72). When comparing the final weight of the intervention group to the comparison group combined with the dropout participants (n = 30), there was a statistically significant difference (p = .009). Future research may focus on evaluating the effectiveness of this program at a larger practice site and including in-person MI sessions rather than phone calls only

A New Schedule Estimation Technique for Construction Projects

Allen studied hundreds of construction projects and developed an accu-rate, practically useful model of their labor profiles. We combine Al-len’s labor profile with standard Earned Value Management (EVM) techniques and derive a simple, practical formula that estimates the fi-nal schedule from early project data. The schedule estimation formula is exact; it requires no approximations. The estimate is also surprisingly accurate and available early enough in the project for the project manager to be able to take appropriate actions. We use one of Allen’s real-world construction data sets to calibrate and validate our theoreti-cal model. Early estimates of the final schedule are remarkably accu-rate, and available early enough to be used to effect management changes. We also explain why a current schedule estimation method, Earned Schedule (ES), has a poor theoretical foundation and show that our model is superior to ES in predicting construction schedule delays. The model should provide warning of schedule delays early enough for project managers to take corrective actions

A low-loss, broadband antenna for efficient photon collection from a coherent spin in diamond

We report the creation of a low-loss, broadband optical antenna giving highly directed output from a coherent single spin in the solid-state. The device, the first solid-state realization of a dielectric antenna, is engineered for individual nitrogen vacancy (NV) electronic spins in diamond. We demonstrate a directionality close to 10. The photonic structure preserves the high spin coherence of single crystal diamond (T2>100us). The single photon count rate approaches a MHz facilitating efficient spin readout. We thus demonstrate a key enabling technology for quantum applications such as high-sensitivity magnetometry and long-distance spin entanglement.Comment: 5 pages, 4 figures and supplementary information (5 pages, 8 figures). Comments welcome. Further information under http://www.quantum-sensing.physik.unibas.c

Quantum and Classical in Adiabatic Computation

Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialised state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose groundstate encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimisation algorithms and quantum adiabatic optimisation. This new perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing - though inconclusive - results

Electric field sensing with a scanning fiber-coupled quantum dot

We demonstrate the application of a fiber-coupled quantum-dot-in-a-tip as a probe for scanning electric field microscopy. We map the out-of-plane component of the electric field induced by a pair of electrodes by measurement of the quantum-confined Stark effect induced on a quantum dot spectral line. Our results are in agreement with finite element simulations of the experiment. Furthermore, we present results from analytic calculations and simulations which are relevant to any electric field sensor embedded in a dielectric tip. In particular, we highlight the impact of the tip geometry on both the resolution and sensitivity.Comment: 10 pages, 4 figure

Voltage-Controlled Optics of a Quantum Dot

We show how the optical properties of a single semiconductor quantum dot can be controlled with a small dc voltage applied to a gate electrode. We find that the transmission spectrum of the neutral exciton exhibits two narrow lines with $\sim 2$ $\mu$eV linewidth. The splitting into two linearly polarized components arises through an exchange interaction within the exciton. The exchange interaction can be turned off by choosing a gate voltage where the dot is occupied with an additional electron. Saturation spectroscopy demonstrates that the neutral exciton behaves as a two-level system. Our experiments show that the remaining problem for manipulating excitonic quantum states in this system is spectral fluctuation on a $\mu$eV energy scale.Comment: 4 pages, 4 figures; content as publishe

Transform-limited single photons from a single quantum dot

A semiconductor quantum dot mimics a two-level atom. Performance as a single photon source is limited by decoherence and dephasing of the optical transition. Even with high quality material at low temperature, the optical linewidths are a factor of two larger than the transform-limit. A major contributor to the inhomogeneous linewdith is the nuclear spin noise. We show here that the nuclear spin noise depends on optical excitation, increasing (decreasing) with increasing resonant laser power for the neutral (charged) exciton. Based on this observation, we discover regimes where we demonstrate transform-limited linewidths on both neutral and charged excitons even when the measurement is performed very slowly