Real-time Domain Research Articles

Numerical Path Integral Approach to Quantum Dynamics and Stationary Quantum States

AbstractApplicability of Feynman path integral approach to numerical simulations of quantum dynamics of an electron in real time domain is examined. Coherent quantum dynamics is demonstrated with one dimensional test cases (quantum dot models) and performance of the Trotter kernel as compared with the exact kernels is tested. Also, a novel approach for finding the ground state and other stationary sates is presented. This is based on the incoherent propagation in real time. For both approaches the Monte Carlo grid and sampling are tested and compared with regular grids and sampling. We asses the numerical prerequisites for all of the above.

Research on the production performance of multistage fractured horizontal well in shale gas reservoir

This paper extends a linear flow model to research the production performance of a multi-fractured horizontal well in a shale gas reservoir. The model considers desorption, diffusion (Knudsen), discontinuous micro-fractures and stimulated reservoir volume (SRV), which are widely accepted as the obvious characteristics of shale gas reservoirs. The solution was derived in the Laplace domain, and then inverted to the real time domain using the numerical algorithm proposed by Stehfest (1970). After that, the log–log curves of rate decline and accumulative production are plotted. Based on the curves, the effects of diffusion, desorption gas, net-fracture system, micro-fractures, fracture permeability and Langmuir volume on production performance were analyzed. These analyses have significant importance for understanding the production decline dynamic in shale gas reservoirs.

Lateral diffusion contributes to FRET from lanthanide-tagged membrane proteins

Diffusion can enhance Förster resonance energy transfer (FRET) when donors or acceptors diffuse distances that are similar to the distances separating them during the donor's excited state lifetime. Lanthanide donors remain in the excited state for milliseconds, which makes them useful for time-resolved FRET applications but also allows time for diffusion to enhance energy transfer. Here we show that diffusion dramatically enhances FRET between membrane proteins labeled with lanthanide donors. This phenomenon complicates interpretation of experiments that use long-lived donors to infer association or proximity of mobile membrane proteins, but also offers a method of monitoring diffusion in membrane domains in real time in living cells.

Consolidation around a tunnel in a general poroelastic medium under anisotropic initial stress conditions

In this study, a solution for the response of a poroelastic medium around a deeply excavated circular tunnel is analytically formulated based on Biot’s consolidation theory. The proposed solution considers the initial anisotropic stress in the medium around lined or unlined tunnels and is an improvement over previous solutions (Carter and Booker, 1982, 1984) because it considers Biot’s coefficient, the combined compressibility of liquid and solid phases in the porous medium, and a thick-walled liner. The solution is expressed using the Laplace transform domain, and numerical inversion techniques are used to obtain real time domain results. The new solution is verified by comparing it with previous analytical solutions and numerical results obtained using the commercial finite element software COMSOL Multiphysics (COMSOL AB, Stockholm, Sweden). Parametric studies are performed to determine the influences of Biot’s coefficient and the combined compressibility and liner properties during the consolidation process.

Real-time application mapping for many-cores using a limited migrative model

Many-core platforms are an emerging technology in the real-time embedded domain. These devices offer various options for power savings, cost reductions and contribute to the overall system flexibility, however, issues such as unpredictability, scalability and analysis pessimism are serious challenges to their integration into the aforementioned area. The focus of this work is on many-core platforms using a limited migrative model ($$ LMM $$LMM). $$ LMM $$LMM is an approach based on the fundamental concepts of the multi-kernel paradigm, which is a promising step towards scalable and predictable many-cores. In this work, we formulate the problem of real-time application mapping on a many-core platform using $$ LMM $$LMM, and propose a three-stage method to solve it. An extended version of the existing analysis is used to assure that derived mappings (i) guarantee the fulfilment of timing constraints posed on worst-case communication delays of individual applications, and (ii) provide an environment to perform load balancing for e.g. energy/thermal management, fault tolerance and/or performance reasons.

A Detailed Analysis of Software Cost Estimation Using Cosmic-FFP

Software cost estimation is one of the most challenging tasks in software engineering. For the estimation, Function points are useful in the business application software domain and problematic in the real-time software domain. Full Function Points (FFP) are useful for functionality-based estimation, specifically for real-time and embedded software. Functional size measurement method that has user view of functional requirements developed by Common Software Measurement International Consortium (COSMIC) called COSMIC-FFP. By using COSMIC-FFP model, an early prediction of the functional complexity of the software throughout the software development life cycle within given budget constraints, reliability can be done. In this paper, a detailed analysis with process flow of COSMIC-FFP model has been discussed.

MLIMAS: A Framework for Machine Learning in Interactive Multi-agent Systems

Abstract Multi-agent systems in complex, real time domains require agents to act effectively both autonomously and as part of a team. The complexity of many tasks arising in these domains makes them difficult to solve with pre-programmed agent behaviors. The agents must instead discover a solution on their own, using learning. In this paper, we present MLIMAS a framework for Machine Learning in Interactive Multi-Agent Systems. The MLIMAS is proposed to provide answers to the issues arising from integrating machine learning algorithms in interactive multi-agent systems, focusing on three questions i) what are the learning targets for agents?, (ii) how can the machine learning system be integrated into the agent architecture?, and (iii) how can agents learn interactively?. MLIMAS addresses those three questions plus supporting multi-agent systems consisting of autonomous and adaptive agents acting in real-time and noisy environments. As a result of such required capabilities, MLIMAS allows dynamic and intelligent behavior of the agents to efficiently achieve their local and coalition goals such through modeling other agents actions, and interactively taking benefits of self and others preferences in learning and achieving the agents goals. We studied the proposed framework in the Taxi Domain compared with the traditional Q-Learning algorithm without interactive share of information. Our experiments showed 2 times improvement for the average award received per agents trail rather than the traditional Q-Learning approach. In addition, we have got %80 improvement for the same number of trials of the agents to reach the passengers.

Symbol Timing Sequence Structure for OFDM-CDMA Communication System under Low SNR

Symbol synchronization offset of orthogonal frequency division multiplexing (OFDM) communication system will cause the rotation of data constellation at receiver even if such offset falls in the range of the appended cyclic prefix. When OFDM modulation is combined with spread spectrum technique, e.g., OFDM code division multiple access (OFDM-CDMA), the problem becomes more serious since OFDM-CDMA communication system generally works under very low signal-to-noise ratio. This paper focuses on symbol timing synchronization of OFDM-CDMA communication system and proposes an effective sequence structure on the basis of circular conjugate-symmetric properties of discrete Fourier transform. The proposed frequency-domain sequence not only can generate real time-domain signal to reduce calculation complexity, but also can resist peak-to-average power ratio of OFDM modulation by exploiting suitable computer search algorithm. The simulation results show a sharp cross-correlation peak can be obtained, which is quite helpful for accurate symbol timing synchronization of OFDM-CDMA communication system.

Validation of Effective Time Translational Invariance and Linear Viscoelasticity of Polymer Undergoing Cross-linking Reaction

In polymeric liquids undergoing cross-linking reactions, rheological properties continuously change as a function of time. Consequently, the materials do not obey the time translational invariance and therefore the principles of linear viscoelasticity. In this work, we propose a methodology in which principles of linear viscoelasticity are transformed from the real time domain to the effective time domain. In the latter, the readjustment of the material clock, which accounts for the time dependency, facilitates validation of the effective time translational invariance. By carrying out experiments on cross-linking PDMS, we show that material that is undergoing time evolution in the real time domain indeed validates the Boltzmann superposition principle and convolution relation relating creep compliance and relaxation modulus in the effective time domain.

Coupled Thermoelasticity Analysis of Annular Laminate Disk Using Laplace Transform and Galerkin Finite Element Method

In this paper, a dynamic analysis of annular laminate disk under radial thermal shock is carried out by employing a Galerkin Finite Element (GFE) approach. The governing equations, including the equation of the motion and energy equation are obtained based on Lord-Shulman theory. These two equations are solved simultaneously to obtain the displacement components and temperature distributions. A simply support boundary condition through outer edge is assumed for the annular disk. The inner radius is subjected to thermal shock and free of any traction. The outer edge is keeping at a constant temperature. Using Laplace transfer technique to transfer the governing equations into the space domain, where the Galerkin Finite Element Method is employed to obtain the solution in space domain. The inverse of Laplace transfer is performed numerically to achieve the final solution in the real time domain. The results are validated with the known data reported in the literature.

Optimization of compute unified device architecture for real-time ultrahigh-resolution optical coherence tomography

We propose an optimized signal processing scheme that utilizes the compute unified device architecture (CUDA) for real-time spectral domain optical coherence tomography (OCT). Because linear spline interpolation and the direct spectral reshaping method have low data and control dependencies, these algorithms maximally utilize graphic processing unit (GPU) resources for dispersion control. In addition, data transfer between main memory and GPU, regarded as one of the most wasteful and time-consuming processes in GPU computing, is executed in parallel with the signal processing by overlapping kernel execution and data transfers. Experimental results obtained from application of the proposed scheme to a laboratory constructed OCT system comprising five spectrally shifted SLDs indicate that the OCT system has an axial resolution of 4.8μm and transverse resolution of 13μm in air. Further, coherence artifacts are reduced by 3–14dB over the side-lobes in the point spread function. The optimization of CUDA enables OCT imaging rates up to 350kHz (A-lines/sec) with a single GTX680 GPU.

Spatial and temporal isolation of virtual CAN controllers

Virtualization is a key technology to enable the use of multi-core processors in automotive embedded systems. For side-by-side execution of mixed-criticality applications that access shared communication infrastructures, a secure and safe virtualization of I/O devices is required, which features a complete spatial and temporal isolation of individual virtual interfaces. We extended existing approaches of hardware-based CAN virtualization to achieve a full isolation while maintaining the bounded latencies achieved in previous implementations. It is shown, that even a denial-of-service attack towards one virtual controller does not influence the behavior of other virtual controllers. In addition, the scheduling mechanism implemented to guarantee temporal isolation can be configured to provide differentiated service levels for real-time and best effort application domains.

Towards hardware embedded virtualization technology

Embedded virtualization possesses inherent challenges which differentiate the domain from traditional virtualization application fields such as server and desktop computing. Standard software virtualization solutions have a negative impact, not only on memory footprint and performance, but also on determinism and interrupt latency which are critical for the embedded real-time domain. Thus, efficient embedded virtualization requires domain-specific software and hardware support. This paper presents work in progress results of hardware-based Hypervisor implementation. The use cases of embedded virtualization are analyzed, justifying the reasoning for hardware-supported virtualization. Architectural and micro-architectural improvements to an ARM v5TE processor are described, demonstrating the performance advantages, and compared against ARM Virtualization Extensions, identifying respective vulnerabilities and providing alternative solutions which enable higher flexibility, minimizing virtualization costs. The research roadmap towards a hardware-complete Hypervisor, based on the presented results, is described.

Real-Time Monte Carlo Tree Search in Ms Pac-Man

In this paper, Monte Carlo tree search (MCTS) is introduced for controlling the Pac-Man character in the real-time game Ms Pac-Man. MCTS is used to find an optimal path for an agent at each turn, determining the move to make based on the results of numerous randomized simulations. Several enhancements are introduced in order to adapt MCTS to the real-time domain. Ms Pac-Man is an arcade game, in which the protagonist has several goals but no conclusive terminal state. Unlike games such as Chess or Go there is no state in which the player wins the game. Instead, the game has two subgoals, 1) surviving and 2) scoring as many points as possible. Decisions must be made in a strict time constraint of 40 ms. The Pac-Man agent has to compete with a range of different ghost teams, hence limited assumptions can be made about their behavior. In order to expand the capabilities of existing MCTS agents, four enhancements are discussed: 1) a variable-depth tree; 2) simulation strategies for the ghost team and Pac-Man; 3) including long-term goals in scoring; and 4) reusing the search tree for several moves with a decay factor γ. The agent described in this paper was entered in both the 2012 World Congress on Computational Intelligence (WCCI'12, Brisbane, Qld., Australia) and the 2012 IEEE Conference on Computational Intelligence and Games (CIG'12, Granada, Spain) Pac-Man Versus Ghost Team competitions, where it achieved second and first places, respectively. In the experiments, we show that using MCTS is a viable technique for the Pac-Man agent. Moreover, the enhancements improve overall performance against four different ghost teams.

Moment equations for chromatography based on Langmuir type reaction kinetics

Moment equations were derived for chromatography, in which the reaction kinetics between solute molecules and functional ligands on the stationary phase was represented by the Langmuir type rate equation. A set of basic equations of the general rate model of chromatography representing the mass balance, mass transfer rate, and reaction kinetics in the column were analytically solved in the Laplace domain. The moment equations for the first absolute moment and the second central moment in the real time domain were derived from the analytical solution in the Laplace domain. The moment equations were used for predicting the chromatographic behavior under hypothetical HPLC conditions. The influence of the parameters relating to the adsorption equilibrium and to the reaction kinetics on the chromatographic behavior was quantitatively evaluated. It is expected that the moment equations are effective for a detailed analysis of the influence of the mass transfer rates and of the Langmuir type reaction kinetics on the column efficiency.

Shape-Dependent Electronic Excitations in Metallic Chains

The electronic excitations of silver chains with different geometries (linear, circle, arc and zigzag chains) have been investigated at the time-dependent density functional theory level, by solving the equation of motion of the reduced single-electron density matrix in the real-time domain. A scaling parameter 0 ≤ λ ≤ 1 has been introduced to adjust the two-electron contributions during propagation in the time domain in a way that allows us to distinguish different electronic excitations — plasmon and single-particle excitations. The dipole responses, in particular the plasmon resonances of these metallic chains to an external δ-pulse, show a strong dependence on their geometric structures. In most cases, the dipole responses of these chains possess great tunability when altering their geometric parameters — the radius of the circle and arc chains, and the bond angle of the zigzag chains. Some excitations in these chains also show a wide tunable excitation energy range, more than 1 eV, making it possible to fine-tune the excitations of the metallic chains at an atomic scale.

Exposure

A wide range of malicious activities rely on the domain name service (DNS) to manage their large, distributed networks of infected machines. As a consequence, the monitoring and analysis of DNS queries has recently been proposed as one of the most promising techniques to detect and blacklist domains involved in malicious activities (e.g., phishing, spam, botnets command-and-control, etc.). EXPOSURE is a system we designed to detect such domains in real time, by applying 15 unique features grouped in four categories. We conducted a controlled experiment with a large, real-world dataset consisting of billions of DNS requests. The extremely positive results obtained in the tests convinced us to implement our techniques and deploy it as a free, online service. In this article, we present the Exposure system and describe the results and lessons learned from 17 months of its operation. Over this amount of time, the service detected over 100K malicious domains. The statistics about the time of usage, number of queries, and target IP addresses of each domain are also published on a daily basis on the service Web page.

Imaging the eye fundus with real-time en-face spectral domain optical coherence tomography

Real-time display of processed en-face spectral domain optical coherence tomography (SD-OCT) images is important for diagnosis. However, due to many steps of data processing requirements, such as Fast Fourier transformation (FFT), data re-sampling, spectral shaping, apodization, zero padding, followed by software cut of the 3D volume acquired to produce an en-face slice, conventional high-speed SD-OCT cannot render an en-face OCT image in real time. Recently we demonstrated a Master/Slave (MS)-OCT method that is highly parallelizable, as it provides reflectivity values of points at depth within an A-scan in parallel. This allows direct production of en-face images. In addition, the MS-OCT method does not require data linearization, which further simplifies the processing. The computation in our previous paper was however time consuming. In this paper we present an optimized algorithm that can be used to provide en-face MS-OCT images much quicker. Using such an algorithm we demonstrate around 10 times faster production of sets of en-face OCT images than previously obtained as well as simultaneous real-time display of up to 4 en-face OCT images of 200 × 200 pixels(2) from the fovea and the optic nerve of a volunteer. We also demonstrate 3D and B-scan OCT images obtained from sets of MS-OCT C-scans, i.e. with no FFT and no intermediate step of generation of A-scans.

A Novel Hybrid Solving Approach Based on Combining Similarity Solutions with Laplace Transformation Technique to Solve Different Engineering Problems

In this study Laplace transformation technique combined with similarity solutions are used to solve PDE involves derivatives with respect to time and two spatial parameters. The hybrid approach is based on transforming the PDE from the real physical time domain to the Laplacian domain. The obtained PDE in the Laplacian domain involves only derivatives with respect to the two spatial parameters. This transformed PDE is then solved by similarity solution approach to convert it from a PDE in the Laplacian domain to an ODE in another domain involves independent parameter consists of the Laplace parameter s and the two independent spatial parameters. A case is discussed to demonstrate the capabilities of the proposed approach in solving different engineering problems.

OBSTACLE DETECTION AND ELECTRONIC NAVIGATION SYSTEM FOR VISUALLY IMPAIRED PERSONS

In This Paper we present a real time domain obstacle detection system for the visually impaired persons to improve their mobility in daily life with the help of obstacle detection sensor installed in their walking stick .System is having a lower cost so it is easily purchasable so it can have a major significance in life of visually impaired persons. This Paper proposes a system to detect any object attached to the floor regardless to their height [1]. Obstacle on the floor in the front of user can be reliably detected in real time using the proposed system implemented by the IR sensor installed on the walk stick of the visually impaired person. Project also contains a navigation system for visually impaired persons to make the life of such persons easier up to some extent. This project is suited for the area where the possibility of blind person is high (like blind school, college)[6]. For transport facility of blind we have first decided the common bus roots of blind then we have placed RF tag to all those buses with unique code. At the second side we have placed RF reader, microcontroller and voice processor. The RF reader receive unique code, microcontroller process this code with defined code, if match found, voice processor get activated and starts speaking bus name, initial destination and final destination. The obstacle detection is also included in the project with voice. The system aims at increasing the mobility of visually impaired people by offering new sensing abilities.