Mihai Secara

Fractional order PD control of an isotope separation columns cascade

Cryogenic isotope separation columns are unique equipments used to produce enriched substances in the isotope of interest for many industrial applications. The control of an isotope separation column is a difficult and challenging task, being a highly nonlinear plant with large time constants and time delays. A single column can enrich only to a low level of concentration, so column cascades are used for high purity final products. A cascade of three isotope separation columns due to the interdependencies between them represents an even more difficult process to control. Due to the fact that in prior studies fractional order controllers have been successfully implemented for a single isotope separation column, the present paper addresses the development of a control system for the isotope separation column cascade using fractional order PD controllers. As design parameters were imposed the phase margin, gain crossover frequency and robustness of process gain variations. The simulation results, evaluated using the nonlinear mathematical model of the process, including all process input effects, prove the efficiency of the method.

Creating a transducer electronic datasheet using I2C serial EEPROM memory and PIC32-based microcontroller development board

The present paper describes a software method for creating / managing one type of Transducer Electronic Datasheet (TEDS) according to IEEE 1451.4 standard in order to develop a prototype of smart multi-sensor platform (with up to ten different analog sensors simultaneously connected) with Plug and Play capabilities over ETHERNET and Wi-Fi. In the experiments were used: one analog temperature sensor, one analog light sensor, one PIC32-based microcontroller development board with analog and digital I/O ports and other computing resources, one 24LC256 I2C (Inter Integrated Circuit standard) serial Electrically Erasable Programmable Read Only Memory (EEPROM) memory with 32KB available space and 3 bytes internal buffer for page writes (1 byte for data and 2 bytes for address). It was developed a prototype algorithm for writing and reading TEDS information to / from I2C EEPROM memories using the standard C language (up to ten different TEDS blocks coexisting in the same EEPROM device at once). The algorithm is able to write and read one type of TEDS: transducer information with standard TEDS content. A second software application, written in VB.NET platform, was developed in order to access the EEPROM sensor information from a computer through a serial interface (USB).

Convergent control of the residual water blunting system used in metallurgy

In this paper, a solution for the pH control of the residual water is presented. The blunting process is treated as a distributed parameter one, its model being expressed using equations with partial derivatives. The modeling-simulation procedure is based on the matrix of partial derivatives of the state vector associated with Taylor series, method that assures a very high accuracy. The convergent control structure is designed in order to obtain higher performances than in the case of using a simple control structure. The differences between the responses of the two control structures are presented in the simulations chapter, using comparative graphs.

Original Extremum control method implemented in MPP photovoltaic systems

The paper presents a novel, original control strategy in order to increase the efficiency of the renewable energy systems. The proposed algorithm uses the Extremum System framework, continuously adjusting the manipulated variable in order to maintain the output as near as possible to its extreme value. The maximum point seeking algorithm is an original, simple one, based on the analysis of the slope sign, realized with sample and hold elements. The advantages of the method are highlighted by simulation results.

Analogy between mission critical detection in distributed systems and 13C isotope separation column

Carbon represents the fourth most abundant chemical element in the world, having two stable and one radioactive isotope. The 13 Carbon isotopes, with a natural abundance of 1.1%, plays an important role in numerous applications, such as the study of human metabolism changes, molecular structure studies, non-invasive respiratory tests, Alzheimer tests, air pollution and global warming effects on plants [2]. Distributed systems are increasingly being applied in critical real-time applications and their complexity forces programmers to use design methods which guarantee correctness and increase the maintainability of the products. Objectoriented methodologies are widely used to cope with complexity in any kind of system, but most of them lack a formal foundation to allow the analysis and verification of designs, which is one of the main requirements for dealing with concurrent and reactive systems. This research is intended to make an analogy between two tips of industrial processes, one 13C Isotope Separation Column and other one distributed systems. We try to highlight detection of „mission critical “situations for this two processes and show with one is more critical and needs deeply supervisyon [1], [3].

The linear and nonlinear behavior analysis for RC-filters

The paper deals with an emerging problem of AC to DC power converters: the establishment of the mean value of the rectified voltage. This is a difficult task due to the nonlinear behavior of the capacitor filter, attached to the rectifiers. Are proposed novel, simplified mathematical models both of the controlled and uncontrolled rectifier, useful in analysis and design stage. A software product is conceived to compute the mean value of the smoothed output voltage of the controlled rectifier. The obtained results are validated both by simulation and by comparison with experimental results, highlighting the advantages of the proposed methods.

Algorithms and control structures for industrial robots TX90 model

The present paper proposes some algorithms and control structures for TX 90 Staubli industrial robot. Are described and simulated different control structures using PID, PI and PD controllers. The behavior of the system is analyzed in all control structures in order to select the best structure.

Variable DC power sources for 13 C isotope separation column boiler supply

Industrial chemical processes are usually very complex, making the control a challenging task. The 13C isotope separation process is highly nonlinear, with slow dynamics and large time delays. Based on previous research and by experimental knowledge it was determined that secondary processes, like boiler carbon monoxide level or condenser liquid nitrogen level, play an important role in the satisfactory operation of the separation column. This paper focuses on the boiler carbon monoxide level and proposes a control solution for the boiler heating. The proposed solution is based on an original version of power transducer and is implemented and tested using Matlab/SIMULINK environment. Simulation results are provided to demonstrate the effectiveness of the proposed solution.

Process modeling and simulation of distributed parameter using (M pdx ) method with approximating solutions

This paper presents a control system where the controlled plant is a distributed parameter process. Numerical simulation of the control system is accomplished using the method of Matrix of Partial Derivatives of the State Vector (Mpdx) associated with Taylor Series. By including a process modeled by a partial differential equation of second order with two independent variables, this presents (Mpdx) method with approximate solutions, which are needed to ensure the start of the calculations and to check the results.

“Chirp” signal generators for frequency response experiments

Several techniques to generate the chirp signal have been proposed over the past few decades. Generally, the techniques can be categorized into analog approach and digital approach. In analog chirp generator usually a voltage controlled oscillator is used to generate the chirp signal. However, due to several limitations of this oscillator the digital approach has slowly takes the role as the chirp generator, although are more complex and hard to realize. This work proposes an easy to use analog alternative for chirp signal generator, which counteracts the claimed disadvantages. The paper presents the principle of the proposed generator, the simulation scheme with the simulation results and an experimental result, highlighting the advantages of the method.