Efficient parallel architecture for highly coupled real-time linear system applications

The solution for the free vibrations of initially disturbed thin elastic rings is obtained by converting the differential equations of motion to two sets of finite difference equations: a conventional set, and a modified set based on a technique first presented by Chuang and Veletsos in their investigation of the static equilibrium of cylindrical shells. In the conventional set, both of the displacement variables are defined at the same location on the finite difference network, but in the modified set the two displacement variables are defined at staggered locations. The analytical frequency equation associated with both sets of difference equations is derived and shown to be correct by an actual computer solution. A sample ring is considered and the superiority of the modified difference equation is shown by comparing the natural frequencies of both sets of difference equations with the exact natural frequencies.

The study of natural convection from a heat source located at the bottom of partially top vented enclosure is presented. Air cooling for electronic component situated at the bottom of a top vented enclosure is studied theoretically. The flow is assumed to be laminar, steady and of constant physical properties. The process is described by continuity, momentum and energy partial differential equations, which are be expressed in Cartesian coordinates system. Due to the nature of the studied problem and with proper transformation of the problem dependent and independent variables, these governing equations are transformed to a set of dimensionless partial differential equations. This set of differential equations is transformed to set of difference equations by the implantation of finite difference technique. Accordingly, one can obtain the solutions for this problem, which are obtained by application of the well known Gauss Siedel iteration method. A computer program is developed to solve the present proposed mathematical model. According to this solution, the values of Nusselt number, for different values of Rayleigh number are obtained. Comparisons between the present obtained results and those results obtained in previous theoretical results are performed for parametric variations of the vent opening size and shape. Also a correlation for Nusselt number as a function of Rayleigh number and equivalent diameter of the vent is proposed.

Kinematic models that account for deformation due to applied loads have recently been developed for a variety of continuum robots. In these cases, a set of nonlinear differential equations with boundary conditions must often be solved to obtain the robot shape. Thus, computing manipulator Jacobians and compliance matrices efficiently is not straightforward. In this paper, we propose a method for obtaining an arc length parametrized Jacobian and compliance matrix. Our approach involves obtaining an augmented Jacobian by propagating the necessary partial derivatives through the model equations, resulting in a new set of differential equations. These equations can be solved as an initial value problem, via a single numerical integration. Our method can be generally applied to various continuum robot architectures, regardless of the specific actuation system used. We provide a specific case study using this method to obtain the Jacobian for a concentric-tube robot.

Using multi-layers method (MLM), a semi-analytical solution have been derived for determination of displacements and stresses in a thick cylindrical shell with variable thickness under non-uniform pressure. Three different profiles (convex, linear and concave) are considered for the variable thickness cylinder. Given the existence of shear stress in the thick cylindrical shell due to thickness and pressure changes along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations with variable coefficients. Given that the thick cylinder with variable thickness is divided into n homogenous disks, n sets of differential equations with constant coefficients are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. Finally, some numerical results are presented to study the effects of applied pressure, thickness profile type, and angular velocity on the mechanical behavior of the cylindrical shell.

A real-time operating system (RTOS) provides a platform for the design and implementation of a wide range of applications in real-time systems, embedded systems, and mission-critical systems. This paper presents a formal design model for a general RTOS known as RTOS+ that enables a specific target RTOS to be rigorously and efficiently derived in real-world applications. The methodology of a denotational mathematics, Real-Time Process Algebra (RTPA), is described for formally modeling and refining architectures, static behaviors, and dynamic behaviors of RTOS+. The conceptual model of the RTOS+ system is introduced as the initial requirements for the system. The architectural model of RTOS+ is created using RTPA architectural modeling methodologies and refined by a set of Unified Data Models (UDMs). The static behaviors of RTOS+ are specified and refined by a set of Unified Process Models (UPMs). The dynamic behaviors of the RTOS+ system are specified and refined by the real-time process scheduler and system dispatcher. This work is presented in two papers; the conceptual and architectural models of RTOS+ is described in this paper, while the static and dynamic behavioral models of RTOS+ will be elaborated in a forthcoming paper.

Generally speaking, real-time system is considered to be able to influence the environment by receiving and processing data, and returning calculation results rapid enough, so as to control the environment. In computer science, real-time system describes the software and hardware system affected by time constraints, and its correctness relies on the logical correctness of the function and the time when the result is generated. According to the main characteristics of real-time operating system, such as time constraint, predictability and reliability, it puts forward higher requirements for the time accuracy and reliability of real-time operating system. This paper first introduces the real-time system from its main characteristics, related concepts and scheduling algorithm. Then five classical graph based task models of real-time system are introduced. Finally, this paper introduces the directed graph realtime task model from two aspects of definition and semantics. As an extension of realtime system task model, directed graph real-time task model is considered to be able to provide real-time systems with stronger expressive power and support the formal study of time constraint problems.

Many advanced ground-based solar telescopes improve the spatial resolution of observation images using an adaptive optics (AO) system. As any AO correction remains only partial, it is necessary to use post-processing image reconstruction techniques such as speckle masking or shift-and-add (SAA) to reconstruct a high-spatial-resolution image from atmospherically degraded solar images. In the New Vacuum Solar Telescope (NVST), the spatial resolution in solar images is improved by frame selection and SAA. In order to overcome the burden of massive speckle data processing, we investigate the possibility of using the speckle reconstruction program in a real-time application at the telescope site. The code has been written in the C programming language and optimized for parallel processing in a multi-processor environment. We analyze the scalability of the code to identify possible bottlenecks, and we conclude that the presented code is capable of being run in real-time reconstruction applications at NVST and future large aperture solar telescopes if care is taken that the multi-processor environment has low latencies between the computation nodes.

Mechanisms are inherently constrained devices. Combining flexibility with mechanisms usually requires using Lagrange multipliers to handle the constraints. The added algebraic or numerical tedium, associated with the Lagrange multipliers, is well documented. Presented in this paper is a technique for obtaining the minimal set of hybrid parameter differential equations for a constrained device. That is, the set of equations that inherently incorporate the constraints. The technique illustrated in this paper is a recently developed hybrid parameter multiple body (HPMB) system modeling methodology. The variational nature of the methodology allows rigorous equation formulation providing not only the complete nonlinear, hybrid differential equations, but also the boundary conditions. The methodology is formulated in the constraint-free subspace of the system’s configuration space, thus Lagrange multipliers are not needed for constrained systems, regardless of the constraint type (holonomic or nonholonomic). To evince the utility of the method, a flexible four bar mechanism is modeled. Particularly, the inversion of the slider crank found in the quick return mechanism. A comparison of Hamilton’s principle and the described technique, as they are applied to the mechanism, is included. It is shown that the same equations result from either method, but the new technique is much more concise, more efficiently handles the constraints, and requires less algebraic tedium.

In this paper, the chemical reactor with the energy changing (non-isotherm) and non-monotonic reactions in a mixed flow is investigated and also the sets of complex nonlinear differential equations obtained from the reaction behavior in these systems are solved by a new method. The set of differential equations are consisted of the mass equilibrium and energy (temperature) changing at concentration governing the reactors. Our purpose is to enhance the ability of solving the mentioned nonlinear differential equation with a simple and innovative approach which entitled ‘’Akbari-Ganji's Method’’ or ‘’AGM’’. Comparisons are made between AGM and numerical method (Runge- Kutta45). The results show that this method is very effective and simple and can be applied for other nonlinear problems. Key words: New method, Akbari-Ganji's method (AGM), nonlinear differential equation, mixed flow, non-monotonic reactions, non-adiabatic, reactor design.

In this paper, a real-time implementation of selective harmonic elimination pulsewidth modulation (SHEPWM) using generalized Hopfield neural network (GHNN) as applied to the single-phase inverter is designed and discussed. Finding the location of the switching instants in the case of SHEPWM involves the solution of a set of nonlinear algebraic transcendental equations. The problem is redrafted as an optimization problem, and it is solved by using GHNN. Though, in principle, then number of harmonics can be eliminated using the presented methodology, this paper tries for the case of the elimination of the 5th-, 7th-, 11th-, and 13th-order harmonics while retaining the desired fundamental. An energy function is formulated for this problem and the set of ordinary differential equations (ODEs) describing the behavior of GHNN is obtained. A program in KEIL C was developed to solve these systems of ODEs by the Runge-Kutta fourth-order method to give the switching instants for continuously varying modulation indexes (M). A MATLAB simulation was carried out, and an experimental setup was also constructed in order to validate the simulated results. The fast Fourier transform analysis of the simulated output voltage waveform and the experimental output voltage waveform confirms the effectiveness of the proposed method. Hence, the proposed method proves that it is much applicable in the industrial applications by virtue of its suitability in real-time applications.

Thermoluminescence governed by the Auger-recombination process

The paper presents a methodology for optimizing the design of large, complex, real-time systems in distributed and parallel processing environments. It can be used as a front-end component in a prototyping process providing increased capabilities for system engineers. The method incorporates various optimization approaches including: heuristic, probabilistic, deterministic, and hybrids. These approaches are applied to the system design structuring techniques and resource allocation techniques to perform optimization and trade-off based on the classes of rules, classes of objective functions, classes of algorithms, sets of analytical equations, and sets of probabilistic reasoning, This method optimizes the system design structure and generates a near-optimal allocation of the logical systems functions onto the implementation resources to meet the overall system requirements.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

research-article Free Access Share on Embedded systems in real time applications, design & architecture Authors: A. L. Suseela View Profile , V. Lalith Kumar View Profile Authors Info & Claims UbiquityVolume 2005Issue AugustAugust 2005 pp 2https://doi.org/10.1145/1088431.1086450Online:01 August 2005Publication History 0citation170,093DownloadsMetricsTotal Citations0Total Downloads170,093Last 12 Months1,290Last 6 weeks56 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteView all FormatsPDF

The derivation of a second-order satellite trajectory predictor in terms of geometrical variables

In this paper, the implementation of a new pupil detection system based on artificial intelligence techniques suitable for real-time and real-word applications is presented. The proposed AI-based pupil detection system uses a classifier implemented with slim-type neural networks, with its classes being defined according to the possible positions of the pupil within the eye image. In order to reduce the complexity of the neural network, a new parallel architecture is used in which two independent classifiers deliver the pupil center coordinates. The training, testing, and validation of the proposed system were performed using almost 40,000 eye images with a resolution of 320 × 240 pixels and coming from 20 different databases, with a high degree of generality. The experimental results show a detection rate of 96.29% at five pixels with a standard deviation of 3.38 pixels for all eye images from all databases and a processing speed of 100 frames/s. These results indicate both high accuracy and high processing speed, and they allow us to use the proposed solution for different real-time applications in variable and non-uniform lighting conditions, in fields such as assistive technology to communicate with neuromotor-disabled patients by using eye typing, in computer gaming, and in the automotive industry for increasing traffic safety by monitoring the driver’s cognitive state.