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The growing demand on the performance of transparent computing systems requires good cache schemes in order to overcome the prolonged network latency. However, evaluating cache schemes, especially measuring the performance of a transparent computing system with particular cache scheme remains challenging. This is because neither method is available to evaluate the effectiveness and efficiency of the cache schemes in transparent computing, nor the simulator has been developed to measure the system performance under particular cache schemes. In this paper, we propose TranSim, a full-featured, high-performance simulation framework for transparent computing. For the first time, TranSim introduces a methodology to evaluate the performance of multi-level cache hierarchies in transparent computing under different cache configurations and cache replacement policies. TranSim can also demonstrate the behavior and performance of the entire transparent computing system rather than only the cache miss/hit rate. Using TranSim, the system designer can quickly evaluate the effectiveness of cache schemes along with the system performance. We construct several experiments to evaluate the effectiveness and efficiency of TranSim. Results show that TranSim can accurately output the performance of both the cache hierarchy and the entire transparent computing system. [ABSTRACT FROM AUTHOR]

Provisioning buffer management mechanism is especially crucial in resource-constrained delay tolerant networks (DTNs) as maximum data delivery ratio with minimum overhead is expected in highly congested environments. However, most DTN protocols do not consider resource limitations (e.g., buffer, bandwidth) and hence, results in performance degradation. To strangle and mitigate the impact of frequent buffer overflows, this paper presents an adaptive and efficient buffer management scheme called size-aware drop (SAD) that strives to improve buffer utilization and avoid unnecessary message drops. To improve data delivery ratio, SAD exactly determines the requirement based on differential of newly arrived message(s) and available space. To vacate inevitable space from a congested buffer, SAD strives to avoid redundant message drops and deliberate to pick and discard most appropriate message(s) to minimize overhead. The performance of SAD is validated through extensive simulations in realistic environments (i.e., resource-constrained and congested) with different mobility models (i.e., Random Waypoint and disaster). Simulation results demonstrate the performance supremacy of SAD in terms of delivery probability and overhead ratio besides other metrics when compared to contemporary schemes based on Epidemic (DOA and DLA) and PRoPHET (SHLI and MOFO). [ABSTRACT FROM AUTHOR]

Flight envelope protection algorithm is proposed to improve the safety of an aircraft. Flight envelope protection systems find the control inputs to prevent an aircraft from exceeding structure/aerodynamic limits and maximum control surface deflections. The future values of state variables are predicted using the current states and control inputs based on linearised aircraft model. To apply the envelope protection algorithm for the wide envelope of the aircraft, online linearisation is adopted. Finally, the flight envelope protection system is designed using adaptive neural network and least-squares method. Numerical simulations are conducted to verify the performance of the proposed scheme. [ABSTRACT FROM PUBLISHER]

This paper describes the High Order (Seventh-order) Predictor-Corrector approach which uses the two previous points and external interpolation to predict the location and energy of the next point based on CFD**-Bofill scheme. The experiment results show the Seventh-order approach is far better than Verlet approach. Parts of the experiment results prove the Seventh-order approach is better than CFD-Bofill updating scheme. However, the other results are not better than CFD-Bofill since the Seventh-order approach, which uses two points to predict the next point indirectly, increases the step size. The external interpolation is worse than the internal interpolation in some cases at the same time. This article proposes a High Order (Seventh-Order) Predictor-Corrector approach which uses the two previous points and external interpolation to predict the location of the next time step. The simulation results show the Seventh-Order approach is far better than Velocity Verlet approach and as well as CFD-Bofill for molecules without hydrogen atoms, while new method is simpler than CFD-Bofill. This is due to the Seventh-Order approach which uses two points to predict the next point indirectly, increases the step size and the external interpolation is worse than the internal interpolation. [ABSTRACT FROM AUTHOR]

A robot interacting with the environment requires that the end effector \hboxposition is tracked and that the forces of contact are kept below certain reference values. For instance, in a rehabilitation session using a robotic device, the contact forces are limited by the allowed strength of the human limbs and their complex-joints. In these cases, a control scheme which considers both position and force control is essential to avoid damage to either the end effector or the object interacting with the robot. This paper therefore develops a real-time force/position control scheme for a three-DOF parallel robot whose end effector holds a DOF one translation (1 T) and two rotations (2 R). The implemented hybrid force/position control considers, as a reference, the normal force on the mobile platform, which is measured by means of a load cell installed on the platform. The position control is designed to track the orientations of the robot either in joint or task space using a model-based control scheme with identified parameters. Moreover, the force control is based on a PD action. The control scheme is developed through simulations, before being applied to an actual parallel robot. The findings show that with the implemented controller, the actual robot accomplishes the reference values for the normal force on the mobile platform, while at the same time the platform accurately follows the required angular orientation. [ABSTRACT FROM AUTHOR]

Guidance with traditional trajectory correction scheme usually starts from the trajectory apex time to reduce drag penalties early in flight; however, this method cannot get the max trajectory correction capability of canards according to our analysis. This paper presents an optimized trajectory correction scheme by taking different control phases of canards in ballistic ascending segment and ballistic descending segment. Simulation indicates that the optimized trajectory correction can improve the trajectory correction capability greatly. The result of an example trajectory and Monte Carlo simulations with the predictive guidance law and the trajectory tracking guidance law testifies the effectiveness of the optimized trajectory correction scheme. [ABSTRACT FROM AUTHOR]

Here we report a precise computer simulation study of the static critical properties of the two-dimensional q -states Potts model using very accurate data obtained from a modified Wang–Landau (WL) scheme proposed by Caparica and Cunha-Netto (2012). This algorithm is an extension of the conventional WL sampling, but the authors changed the criterion to update the density of states during the random walk and established a new procedure to windup the simulation run. These few changes have allowed a more precise microcanonical averaging which is essential to a reliable finite-size scaling analysis. In this work we used this new technique to determine the static critical exponents β , γ , and ν , in an unambiguous fashion. The static critical exponents were determined as β = 0.10811 ( 77 ) , γ = 1.4459 ( 31 ) , and ν = 0.8197 ( 17 ) , for the q = 3 case, and β = 0.0877 ( 37 ) , γ = 1.3161 ( 69 ) , and ν = 0.7076 ( 10 ) , for the q = 4 Potts model. A comparison of the present results with conjectured values and with those obtained from other well established approaches strengthens this new way of performing WL simulations. [ABSTRACT FROM AUTHOR]

In this study, a numerical model based on the non-oscillatory and non-free parameter dissipation (NND) finite difference scheme for shallow water wave equations including sediment concentration is established in order to simulate the phenomena for dam-break flow and the development of alluvial plain in an estuary. Some numerical experiments show that the numerical model is feasible and efficient for simulating the phenomena for dam-break flow and the development of alluvial plain in an estuary. [ABSTRACT FROM AUTHOR]

In this paper, we consider a control problem of a non-holonomic multi-agent system. We assume that agents and obstacles are in a circular shaped work area. We propose a novel potential-function-based control scheme that drives agents from the initial to the goal configuration while avoiding collision with other agents, obstacles, and the boundary of the work area. The control scheme enables agents to avoid being trapped at local minima by forcing them to exit from the regions that may contain local minima. A numerical simulation is presented to demonstrate the validity of the proposed control scheme. [ABSTRACT FROM PUBLISHER]

This paper proposes a cooperative diversity transmission scheme by superposition coding relaying (SC-relaying) for a wireless system with multiple relays. In this scheme, two layer signals, i.e., signal $${x_1}$$ and $${x_2}$$ , are transmitted from a base station (BS) in the first and the second time slot, while signal $${x_1}$$ is also forwarded from multiple relays to a user in the second time slot. The two layer signals ( $${x_1}$$ and $${x_2}$$ ) meet and superimpose with each other in the air in the second time slot. Then successive interference cancellation (SIC) is used for decoding at the user. In this paper, the optimal power allocation that maximizes the sum throughput of $${x_1}$$ and $${x_2}$$ is first studied. Then the optimal number of selected relays and optimal transmission rate at the BS is derived. Finally the outage probability and diversity gain of the transmission of $${x_1}$$ and $${x_2}$$ is evaluated for system robustness. Simulation results show that the proposed scheme realizes the goal of increasing spectral efficiency and enhancing system robustness. [ABSTRACT FROM AUTHOR]

For multi-field simulations involving a larger number of different physical fields and in cases where the involved fields or simulation codes change due to new modelling insights, e.g., flexible and robust partitioned coupling schemes are an important prerequisite to keep time-to-solution within reasonable limits. They allow for a fast, almost plug-and-play combination of existing established codes to the respective multi-field simulation environment. In this paper, we study a class of coupling approaches that we originally introduced in order to improve the parallel scalability of partitioned simulations. Due to the symmetric structure of these coupling methods and the use of 'long' vectors of coupling data comprising the input and output of all involved codes at a time, they turn out to be particularly suited also for simulations involving more than two coupled fields. As standard two-field coupling schemes are not suited for such cases as shown in our numerical results, this allows the simulation of a new range of applications in a partitioned way. [ABSTRACT FROM AUTHOR]

A fault-tolerant and practically stabilizing simulation of an atomic register is presented. The simulation works in asynchronous message-passing systems, and allows a minority of processes to crash. The simulation stabilizes in a practically stabilizing manner, by reaching a long execution in which it runs correctly. A key element in the simulation is a new combinatorial construction of a bounded labeling scheme accommodating arbitrary labels, including those not generated by the scheme itself. [ABSTRACT FROM AUTHOR]

This paper presents an agile simulation-aided shape editing system for personal fabrication applications. The finite element structural analysis and geometric design are seamlessly integrated within our system to provide users interactive structure analysis feedback during mesh editing. Observing the fact that most editing operations are actually local, a domain decomposition framework is employed to provide unified interface for shape editing, FEM system updating and shape optimization. We parameterize entries of the stiffness matrix as polynomial-like functions of geometry editing parameters thus the underlying FEM system can be rapidly synchronized once edits are made. A local update scheme is devised to re-use the untouched parts of the FEM system thus a lot repetitive calculations are avoided. Our system can also perform shape optimizations to reduce high stresses in model while preserving the appearance of the model as much as possible. Experiments show our system provides users a smooth editing experience and accurate feedback. [ABSTRACT FROM AUTHOR]

Cognitive radio (CR) is a promising technology to improve the utilisation of wireless spectrum resources. Spectrum sensing is the core functionality in CR networks (CRN). When there exist malicious users (MUs) in CRN and MUs start to attack the network after accumulating reputation to some extent, the performance is deteriorated. In this paper, a scheme is proposed by employing Orthogonalized Gnanadesikan–Kettenring (OGK) to mitigate the effect of MUs without the assistance of trusted nodes, and it can improve the robustness of CRN. Simulations verify the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

Accuracy of velocity–vorticity ( V → , ω → )-formulations over other formulations in solving Navier–Stokes equation has been established in recent times. However, the issue of non-satisfaction of solenoidality conditions on vorticity is not addressed in the literature which can possibly lead to non-physical solution. In this respect, here, we have developed and reported conservative rotational form of the ( V → , ω → )-formulation which preserves the solenoidality condition on vorticity in a much simpler way compared to other formulations. Superiority of rotational form over the conventional Laplacian form of ( V → , ω → )-formulation is also shown [by comparing the results for flows inside cubical lid driven cavity (LDC)]. For solving the 3D Navier–Stokes equation using a staggered grid, we use optimized compact schemes for (a) interpolation and (b) evaluation of first and second derivatives. As illustrations, we have solved problems of (i) flow inside a 3D lid driven cavity (LDC), whose solutions are compared with experimental results reported by Koseff and Street [19] and (ii) 3D transitional flow of an equilibrium zero pressure gradient (ZPG) boundary layer over a flat plate as demonstration of the effectiveness of the rotational form of ( V → , ω → )-formulation. [ABSTRACT FROM AUTHOR]

Abstract: This paper addresses estimation fusion in the presence of possible mismatches of sensor model. The main concerns of the paper lie in two aspects. One is to improve the filter performance of the single sensor when there are possible mismatches about the sensor model. The other one is to adopt a good fusion scheme to combine local estimates. For these purposes, the measurement process of the local sensor is modeled by multiple models firstly, and the IMM (interacting multiple model) estimator is implemented to produce estimates for individual models. Next, we describe the local estimate by a Gaussian mixture rather than a single Gaussian density in the baseline IMM filter. Such a GMM (Gaussian mixture model) representation of the system state allows us to keep the detailed information about the local tracker, which contributes to the further fusion if treated properly. Finally, the fusion of two Gaussian mixtures is done in the probabilistic framework, and a close-form solution is derived without complex numerical operations. Simulation results demonstrate the effectiveness of the proposed approach. [Copyright &y& Elsevier]

Molecular simulation could provide detailed description of fluid systems when compared to experimental techniques. They can also replace equations of state; however, molecular simulation usually costs considerable computational efforts. Several techniques have been developed to overcome such high computational costs. In this paper, two early rejection schemes, a conservative and a hybrid one, are introduced. In these two methods, undesired configurations generated by the Monte Carlo trials are rejected earlier than it would when using conventional algorithms. The methods are tested for structureless single-component Lennard–Jones particles in both canonical andNVT-Gibbs ensembles. The computational time reduction for both ensembles is observed at a wide range of thermodynamic conditions. Results show that computational time savings are directly proportional to the rejection rate of Monte Carlo trials. The proposed conservative scheme has shown to be successful in saving up to 40% of the computational time in the canonical ensemble and up to 30% in theNVT-Gibbs ensemble when compared to standard algorithms. In addition, it preserves the exact Markov chains produced by the Metropolis scheme. Further enhancement forNVT-Gibbs ensemble is achieved by combining this technique with the bond formation early rejection one. The hybrid method achieves more than 50% saving of the central processing unit (CPU) time. [ABSTRACT FROM AUTHOR]

With the emergence of petascale computing platforms, high-fidelity computational aeroacoustics (CAA) simulation has become a feasible, robust and accurate tool that complements theoretical and empirical approaches in the prediction of sound levels generated by aircraft airframes and engines. Differentiating itself from the broader discipline of computational fluid dynamics, CAA is particularly challenging as it demands high accuracy, good spectral resolution, and low dispersion and diffusion errors from the underlying numerical methods. Large eddy simulation based on space-implicit high-order compact finite difference schemes has been shown to meet such stringent requirements. In this paper, we discuss a new, scalable parallelization scheme with a three-dimensional computational space partitioning. Unlike many traditional multiblock computational fluid dynamics (CFD) methods, our partitioning is non-overlapping. We use the truncated SPIKE algorithm to solve the governing equations accurately and limit one-sided biased differentiation to just the physical boundaries. We present experimental performance data collected on Kraken and Ranger, two near-petascale computing platforms. [ABSTRACT FROM AUTHOR]

P4 polyphase code is well known in pulse compression technique. For P4 code with length 1000, peak sidelobe level (PSL) and integrated sidelobe level (ISL) are −36dB and −16dB, respectively. In order to increase the performance, there are different reduction techniques to reduce the sidelobes of P4 code. This paper presents a novel sidelobe reduction technique that reduces the PSL and ISL to −127dB and −104dB, respectively. Also, other sidelobe reduction techniques such as Woo filter are investigated and compared with the novel proposed technique. Simulations and results show that the proposed technique produces a better peak side lobe ratio (PSL) and integrated side lobe ratio (ISL) than other techniques. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new approach of using computationally cheap surrogate models for optimization of SMB chromatography is presented. [•] Two different types of surrogate models are developed to replace the detailed but expensive full-order SMB model for optimization. [•] The trust-region framework is proposed to implement an efficient and reliable management of both types of surrogates. [•] The results show that the new scheme not only converges to the optimum obtained with the full-order system, but also yields significant computational advantages. [Copyright &y& Elsevier]

Unequal spaced channel allocation (USCA) is a technique to reduce Four wave mixing (FWM). In this paper, system performance of 8 channel WDM system considering different optical transmitter formats (RZ, NRZ, Raised cosine and Gaussian) using USCA has been evaluated in terms of Q-factor. The simulation results reveal that four wave mixing is minimum for NRZ format. Also the effect of changing the laser power and increasing the bit rate has been observed. [ABSTRACT FROM AUTHOR]