Iulia Clitan

Modeling and Simulation of the Gas Absorption Process in the Liquid Phase

In this paper, a solution for the modeling and simulation of the gas absorption process in a liquid is presented. In the modeling procedure, the technological process is decomposed in two sub-processes connected in series, the first sub-process being considered a lumped parameter one, respectively the second sub-process being considered a distributed parameter one. In order to simulate, with a high accuracy, a process that includes in its structure a distributed parameter sub-process, an original method based on the matrix of partial derivatives of the state vector, associated with Taylor series, is used. The modeling-simulation procedure introduces the premise to approximate the concentration value of the gas absorbed in liquid, in relation to the initial pressure from the reactor, respectively the premise of including the technological process in a concentration control structure.

Optimizing the casting length of single diameter steel billets based on minimum cost

The hot rolling process uses, as raw material, round bars casted using continuous casting at the steel making plant. From here a limited number of casted billets, in terms of length, can be delivered. The supply order for the rolling process is unpredictable and imprecise, thus in this scenario the current paper intends to offer a solution to the industrial partner as to optimize the casting lengths of billets, considering the restrictions of the casting process, and to achieve minimum production cost. An order is converted into a number of billets that should be casted at an ideal length. Two different methods are proposed, an analytical one, designed by the authors, and the linear programming method, in order to generate an optimal solution to the stated problem based on minimizing a cost function. The analytical methods result is the optimal number of steel blocks that need to be casted at a single length, from the limited set. The linear programming methods result is the optimal number of blocks that need to be casted from each available length. The results obtained from both methods are compared based on a set of casting orders via successive simulations.

Optimization of the Casting Length of Billets and Computation of Minimum Number of Steel Batches

This paper deals with the optimization of the casted billet’s lengths, in the context of diverse received orders. Linear programming is used in order to solve the optimization problem, such that minimum cost for the optimal lengths results. A technological constraint is that the number of resulted billets for each casted length must be an integer one. The authors also propose an algorithm for determining the number of batches of liquid steel needed to cover all pieces at optimal lengths for the diverse orders, and also the scheduling order of the casting process.

Measured signal identification and temperature controller design for a HIPEC device

Peritoneal Carcinomatosis (PC) is an abdominal cancer for which cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (HIPEC) proved to be a promising treatment. HIPEC requires the intraperitoneal spread of cytostatic solution at high temperatures (41-43°C) accomplished within 60-120 minutes, during surgical interventions. This paper presents the heating systems identification, by using a graphical fitting method on a temperature measured signal, for a HIPEC device intended to be developed. Also the design of two PID temperature controllers is presented, using the Strejc design method and the Ziegler-Nichols method. The two feedback control structures are compared via simulation, based on their step response signals and their overall performances.

Control structure design for an 18O isotope separation column

This paper presents the design of a control structure that ensures a constant isotopic concentration at the output of the 18O isotope cascade separation column, with an overshoot as small as possible. This paper focuses on obtaining a PID type controller, using the relay method as tuning method, due to the nonlinear behavior of the plant. The controller parameters are adjusted in order to achieve a suitable step response through computer simulation, using the plant fractional - order model. Further, a fractional - order PID controller is tuned in order to improve the control signal, so as to fit within the range of unified currents variation, 0 to 16 mA.

Modeling of the 18O isotope separation process

In this paper, some solutions for the 18O isotope separation process identification are proposed. In this context, both integer-order and fractional-order models are comparatively tested. Using the mean square error as quality indicator, the model considered as the identification problem solution is determined. Some interesting simulations are presented in the end of the paper, which prove both the determined model validity and generality at the input signal variation.

Digital Temperature Control for an Hyperthermic Intraperitoneal Chemotherapy Equipment

This paper presents the design of a digital temperature controller for cytostatic solution used in hyperthermic intraperitoneal chemotherapy (HIPEC). Cytoreductive surgery and HIPEC technique, i.e. Regional chemotherapy using cytostatic drugs at high temperatures of 42-43°C, represents a treatment technique for cancer patients suffering of peritoneal carcinomatosis. The main challenge is to maintain the desired temperature of the cytostatic solution in the intraperitoneal cavity, thus, avoiding local abdominal injuries and systemic hyperthermia. In order to maintain the adequate temperature a digital controller is designed using the Dahlin algorithm, a model based design technique.

Modeling a Chemical Exchange Process for the 13C Isotope Enrichment

This paper presents a solution for modeling a chemical exchange process carbon dioxide (CO2) – carbamate for the 13C isotope enrichment. A big difficulty in the process modeling procedure is the fact that it is a non-linear one. In order to solve this problem, an original modeling solution that permits the process simulation for the entire domain of the values of the input signal is used. The process modeling is made in order to include it in an automatic control structure of the 13C isotope concentration. Some relevant simulations of the open loop process are presented, both in the case when the disturbances do not occur and the case when they occur in the system.

Experimental Identification of Heating Process from Hyperthermic Intraperitoneal Chemotherapy (HIPEC) Equipment

Peritoneal Carcinomatosis (PC) carries a worse prognosis than other sites of systemic metastases. The combination of complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) is on the verge of becoming the gold-standard treatment of PC, when feasible. In order to develop a HIPEC equipment, with complex inflow distribution system having multiple nozzles and a multipoint temperature measurement system, model based techniques will be used by the authors in order to design heating and flow controllers. Thus a functional model is needed for the concerned process such that the simulated model and the behavior of the real system coincide. This paper presents the experimental identification of the heater used on each of the flow channels that result in a transfer function model for the heating process. Also the model for the temperature sensor is obtained

Modeling and Simulation of a Hydroelectric Process

In this paper, a solution for the mathematical modeling and simulation of the technological process associated to a turbine – synchronous generator group, belonging to a small hydroelectric power plant. In order to determine the parameters of the treated technological process, some experimental identification procedures are applied. The experimental identification procedures are applied to the experimental data obtained from the real plant. The validity of the obtained mathematical model is proved through the comparison of the experimental data with the data obtained after the model simulation. The technological importance of having a valid mathematical model of the hydroelectric process consists in the possibility to study the plant behavior for different working regimes using the results of the model simulation and in the possibility of including the process in an automatic control structure.