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The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm. [ABSTRACT FROM AUTHOR]

A new type of rat-race coupler, based on electromagnetic bandgap (EBG)-loaded half-mode substrate integrated waveguide (HMSIW) and composite right/left-handed (CRLH) HMSIW, has been proposed and investigated comprehensively. It consists of three sections of EBG-loaded HMSIWs with 90° phase delay and one section of CRLH HMSIW with −90° phase advance. Due to the evanescent-mode of EBG-loaded HMSIW and the backward behavior of the CRLH HMSIW in the left-handed region, the size of such a miniaturized rat-race coupler is reduced about 65.7% in comparison with its conventional counterpart. The rat-race coupler with the central frequency of 5.5 GHz has been designed and fabricated so as to validate our method, and its good performance is demonstrated by both simulated and measured results. [ABSTRACT FROM AUTHOR]

In this article, we apply the simulated annealing algorithm to determine optimally spaced inspection times for the two-parameter Weibull distribution for any given progressive Type-I grouped censoring plan. We examine how the asymptotic relative efficiencies of the estimates are affected by the position of the monitoring points and the number of monitoring points used. A comparison of different inspection plans is made that will enable the user to select a plan for a specified quality goal. Using the same algorithm, we can also determine an optimal progressive Type-I grouped censoring plan when the inspection times and the expected proportions of total failures in the experiment are pre-fixed. Finally, we discuss the sample size and the acceptance constant of the progressively Type-I grouped censored reliability sampling plan when the optimal inspection times are used. [ABSTRACT FROM AUTHOR]

A novel frequency analysis algorithm for segmentation of textured cells is presented. The algorithm is developed based on an ideal simulation model and is applicable to real cell images. A simulated cell image is assumed to have an ellipse-like region of textured interior embedded in a relatively flat background. The size of the original image is expanded multiple times by extrapolating it to additional regions with estimated background intensities before a larger sized discrete Fourier transform (DFT) is applied. The idealised model for the cell images shows a direct relationship between the boundaries of the cell regions and the inner zero-crossing lines in the large-sized DFT of the expanded images. The shape, size and orientation of the cell region are determined by the parameters derived from the estimated inner zero-crossing line in the DFT whereas the position of the cell region is determined by searching for the location of the minimum in the moving average with the window shaped the same as the previously acquired cell region. Experimental results of both the simulated and the real microscopic cell images are provided to show the performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A compact dual-band bandpass filter is proposed using asymmetrical dual stepped-impedance stub-loaded open-loop resonators, where additional transmission zeros are introduced so as to improve its upper rejection. Its mode characteristics and generation of its transmission zeros are analyzed theoretically. In such a filter, double resonators have different configurations, with their individual transmission zeros generated at different frequencies. It is demonstrated that the realized filter has good performance in frequency selectivity and spurious suppression. Also, good agreement is obtained between its simulated and measured S-parameters. Its -20 dB upper stopband is improved up to 2.57 times of the first central frequency, which is much better than its previous dual-band counterparts with small frequency ratios. [ABSTRACT FROM AUTHOR]

Simulation of excimer ultraviolet (EUV) emission from a coaxial xenon excimer ultraviolet lamp driven by distorted bipolar square voltages is presented in this study. A self-consistent radial one-dimensional fluid model, considering local mean energy approximation (LMEA), along with a set of simplified xenon plasma chemistry was employed to simulate the discharge physics and chemistry. Emitted powers of EUV light and deposited powers to the charged species were simulated by varying the values of four key parameters, which include the driving frequency, gas pressure, gap distance and number of dielectric layers. Results show that there are three distinct periods that include pre-discharge, discharge and post-discharge ones. It is found that intensive EUV (172 nm) emission occurs during the early part of the discharge period, which correlates very well in time with the power deposition through electrons. In addition, power deposition through $$ {\text{Xe}}^{ + } $$ and $$ {\text{Xe}}_{2}^{ + } $$ occurs mainly in the discharge period and later part of discharge period, respectively. Surprisingly, the emission efficiency of 172 nm increases slightly with increasing driving frequency of power source, while it increases dramatically with increasing gap distance. In addition, the maximal emission efficiency is found to take place at gas pressure of 600 torr. The emission efficiency of one-dielectric case is found to be better than that of two-dielectric one. The underlying mechanisms in the above observations are discussed in detail in the paper. [ABSTRACT FROM AUTHOR]

The growing complexity of patient care requires that emergency physicians (EPs) master not only knowledge and procedural skills, but also the ability to effectively communicate with patients and other care providers and to coordinate patient care activities. EPs must become good team players, and consequently an emergency medicine (EM) residency program must systematically train these skills. However, because teamwork-related competencies are relatively new considerations in health care, there is a gap in the methods available to accomplish this goal. This article outlines how teamwork training for residents can be accomplished by employing simulation-based training (SBT) techniques and contributes tools and strategies for designing structured learning experiences and measurement tools that are explicitly linked to targeted teamwork competencies and learning objectives. An event-based method is described and illustrative examples of scenario design and measurement tools are provided. [ABSTRACT FROM AUTHOR]

The ranking and selection problem has been well-studied in the case of continuous responses. In this paper, we address the situation in which continuous responses are replaced by discrete orderings. When individuals in the population provide exhaustive rank-orderings of the alternatives, two common decision rules are the majority rule and the rank-sum method. In the former case, the alternative receiving the most first-place votes is declared superior, while in the latter, the alternative with the smallest rank-sum is deemed the best. Both the Pitman efficiencies and the lower bounds on Bahadur efficiencies of the majority rule relative to the rank-sum method are derived, assuming that the rank data are generated from either the Plackett–Luce or the translative strengths models. In addition, finite sample properties of the two methods are compared with the maximum likelihood approach through simulation studies. Our results suggest two things. First, when it is substantially more difficult to obtain a complete rank-ordering than simply the top choice, the majority rule performs adequately and efforts would be better spent asking many voters to provide top choice rather than fewer voters to provide complete orderings. Second, the rank-sum rule compares favorably to, and is substantially more robust than, the maximum likelihood approach. [Copyright &y& Elsevier]

This article discusses the properties of various knockout tournament designs and presents theoretical results. Potential playoff schemes for Division I-A football are examined via simulation studies. Several metrics are used to assess the relative merits of playoff scenarios, which differ in number, selection, and seeding of playoff teams. Most suggest that college football would benefit from a limited playoff system. Interestingly, for the class of playoff systems examined, the number of teams influences the performance far more than does the seeding procedure. [ABSTRACT FROM AUTHOR]

This paper describes the numerical analysis of the flow structure of a single underexpanded argon free jet issuing into a lower-pressure or vacuum environment using the parallel three-dimensional direct simulation Monte Carlo (DSMC) method employing dynamic domain decomposition. Unstructured and tetrahedral solution-based refined mesh depending on the local mean free path is used to improve the resolution of solution. Simulated Knudsen numbers of the stagnation conditions based on orifice diameter, Reynolds numbers based on the conditions at the orifice exit, and stagnation-to-background pressure ratios are in the range of 0.0005-0.1, 7-1472, and 5-∞, respectively, where "∞" represents vacuum condition in the background environment. Results show that centerline density decays in a rate proportional to the inverse of the square of the axial distance (z-2) from the orifice for all ranges of flow in the current study. The more rarefied the background condition is, the longer the z-2-regime is. In addition, a distinct flow structure, including barrel shock, Mach disk and jet boundary, is clearly identified as the Knudsen number reaches as low as 0.001. Predicted location and size of Mach disk in the near-continuum limit (Kn = 0.001, 0.0005) are found to be in reasonable agreement with experimental results in the continuum regime. [ABSTRACT FROM AUTHOR]

Abstract: This article presents a simplified means of controlling the experiment-wise risk of declaring too many effects active when analyzing an unreplicated orthogonal design. The method begins by assuming a lower bound on the number of null effects. The regression method of backward elimination is followed, comparing each F statistic with a common critical value, until the first statistically significant outcome. By using a single critical value, the method is simpler than the approach of and and is sometimes more powerful. Simulation is used to demonstrate the actual risk of Type I errors and power under various configurations of the true regression coefficients. [Copyright &y& Elsevier]

Abstract: In this paper, a second-order scheme for the Quiet Direct Simulation (QDS) of Eulerian fluids is proposed. The QDS method replaces the random sampling method used in Direct Simulation Monte Carlo (DSMC) methods with a technique whereby particles are moved, have their properties distributed onto a mesh, are destroyed and then are recreated deterministically from the properties stored on the mesh using Gauss–Hermite quadrature weights and abscissas. Particles are permitted to move in physically realistic directions so flux exchange is not limited to cells sharing an adjacent interface as in conventional, direction decoupled finite volume solvers. In this paper the method is extended by calculating the fluxes of mass, momentum and energy between cells assuming a linear variation of density, temperature and velocity in each cell and using these fluxes to update the mass, velocity and internal energy carried by each particle. This Euler solver has several advantages including large dynamic range, no statistical scatter in the results, true direction fluxes to all nearby neighbors and is computationally inexpensive. The second-order method is found to reduce the numerical diffusion of QDS as demonstrated in several verification studies. These include unsteady shock tube flow, a two-dimensional blast wave and of the development of Mach 3 flow over a forward facing step in a wind tunnel, which are compared with previous results from the literature wherever is possible. Finally the implementation of QUIETWAVE, a rapid method of simulating blast events in urban environments, is introduced and the results of a test case are presented. [Copyright &y& Elsevier]

Abstract: In this study, the application of the two-dimensional direct simulation Monte Carlo (DSMC) method using an MPI-CUDA parallelization paradigm on Graphics Processing Units (GPUs) clusters is presented. An all-device (i.e. GPU) computational approach is adopted where the entire computation is performed on the GPU device, leaving the CPU idle during all stages of the computation, including particle moving, indexing, particle collisions and state sampling. Communication between the GPU and host is only performed to enable multiple-GPU computation. Results show that the computational expense can be reduced by 15 and 185 times when using a single GPU and 16 GPUs respectively when compared to a single core of an Intel Xeon X5670 CPU. The demonstrated parallel efficiency is 75% when using 16 GPUs as compared to a single GPU for simulations using 30 million simulated particles. Finally, several very large-scale simulations in the near-continuum regime are employed to demonstrate the excellent capability of the current parallel DSMC method. [Copyright &y& Elsevier]