Short-time System Research Articles

Minimum Initial Marking Estimation of Labeled Petri Nets Based on GRASP Inspired Method (GMIM)

This paper deals with the problem of estimating the Minimum Initial Marking (MIM) of Labeled Petri Nets (L-PN). By the observation of a sequence of labels, we determine the set of possible MIMs related to a given L-PN through an approach based on GRASP (Greedy Randomized Adaptive Search Procedure) inspired method – GMIM. The objective is to get the maximum of feasible MIMs by exploring the search space and giving best solutions for real time cyber systems in short time. We consider four basic assumptions during the reasoning: (i) the L-PN structure is known; (ii) for each transition of L-PN, a label is associated, (iii) the label sequence is known, and (iv) all transitions of L-PN are observable. We show the validity and efficiency of our approach by applying the proposed GMIM metaheuristic to two validation examples: Initialization of two parallel machines (example widely cited in literature) and resources allocation in a monitoring problem via mobile robot network.

Design of a modern automatic control system for the activated sludge process in wastewater treatment

The Activated Sludge Process (ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modified controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48days are achieved for the concentration of microorganisms, (reference value step increase of 50mg·L−1) and 0.01days for the concentration of oxygen (reference value step increase of 0.1mg·L−1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of 5×103m3·d−1 are small. Changes in the reference values of oxygen and microorganisms (increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance (increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.

Impurities as a quantum thermometer for a Bose-Einstein condensate

We introduce a primary thermometer which measures the temperature of a Bose-Einstein Condensate in the sub-nK regime. We show, using quantum Fisher information, that the precision of our technique improves the state-of-the-art in thermometry in the sub-nK regime. The temperature of the condensate is mapped onto the quantum phase of an atomic dot that interacts with the system for short times. We show that the highest precision is achieved when the phase is dynamical rather than geometric and when it is detected through Ramsey interferometry. Standard techniques to determine the temperature of a condensate involve an indirect estimation through mean particle velocities made after releasing the condensate. In contrast to these destructive measurements, our method involves a negligible disturbance of the system.

Equalization Digital On-Channel Repeater in the Single Frequency Networks

Digital On-Channel Repeater (DOCR) can be used for Single Frequency Networks (SFN's). It is much simple and low cost compared to Distributed Transmitter which needs Studio to Transmitter Link (STL). However, traditional DOCR has one of those defects such as a power limit, a long time system processing delay or a poor output signal quality. In order to overcome all of those defects, we introduce Equalization DOCR (EDOCR) which regenerates the original 8-VSB output signal with relatively short time system processing delay. Lab. and Field test results show that the EDOCR can eliminate the loop-back signal up to 5.5 dB with 5.5 /spl mu/s system processing delay. By using EDOCR, we can save spectrum resources and extend coverage areas.

Systematic design method of stabilization fuzzy controllers for pendulum systems

A systematic method to construct stabilization fuzzy controllers for a single pendulum system and a series-type double pendulum system is presented based on the single input rule modules (SIRMs) dynamically connected fuzzy inference model. The angle and angular velocity of each pendulum and the position and velocity of the cart are selected as the input items. Each input item is given with a SIRM and a dynamic importance degree. All the SIRMs have the same rule setting. The dynamic importance degrees use the absolute value(s) of the angle(s) of the pendulum(s) as the antecedent variable(s). The dynamic importance degrees are designed such that the upper pendulum angular control takes the highest priority and the cart position control takes the lowest priority when the upper pendulum is not balanced upright. The control priority orders are automatically adjusted according to control situations. The simulation results show that the proposed fuzzy controllers have high generalization ability to completely stabilize a wide range of single pendulum systems and series-type double pendulum systems in short time. By extending the architecture, a stabilization fuzzy controller for a series-type triple pendulum system is even possible. © 2001 John Wiley & Sons, Inc.

Schrödinger's Equation as a Model Approach to Short Time-Scale Quantum Kinetics in a Semiconductor.

We present a new approach to quantum kinetics based on a Schr{umlt o}dinger{close_quote}s equation formalism. As an example we apply this method to a coupled electron-LO phonon system in a semiconductor. We demonstrate that it is possible to compute the full many-body wave function of the electron-phonon system for short times. The time-dependent electron probability distribution, extracted from the many-body wave function, illustrates the non-Markovian nature of the early time kinetics. The retarded onset of dissipation and kinetic energy overshoots are explained through virtual, nonresonant transitions. {copyright} {ital 1996 The American Physical Society.}

Time-series expansion for reaction processes.

The temporal evolution of reactive systems is studied by means of the exact enumeration of all states of the system for short times. An algorithm for the evaluation of the power series for the basic quantities of interest is presented. In addition, a consistent method of estimating the asymptotic behavior of the series is suggested. This approach is applied to two reaction schemes, ballistic annihilation and diffusive-driven three-species annihilation, where previous Monte Carlo simulations suggest power-law decays for the concentration. In both cases, reasonable estimates for the decay exponents are obtained.

Studies on Homologous Disease Using Germfree Mice.J. C. Salomon

SummaryStudies of homologous disease in newborn mice using axenic and conventional animals (a) provide evidence that for the same dosage of cells, populations of spleen cells have different effects according to their origin. They are more efficient if donors are conventional or immunized axenic, and less efficient if the donors are only axenic. The basis for these differences has not been determined. (b) Provide no evidence that super-infection plays a role in the G.V.H. reaction in this short time system; (c) definitely separate homologous disease of newborn from similar syndromes induced by other investigators with experimental infectious agents.The cooperation and help of Dr. G. A. Voisin and Dr. R. Kinsky are gratefully acknowledged. We also appreciate the invaluable technical assistance given by Mrs. A. Collard and Miss J. Deloupe.