High-quality Control Systems Research Articles

MATHEMATICAL MODEL OF THE HEATER WITH INTERMEDIATE HEAT

Track heaters are one of the technological equipment’s elements of oil and gas condensate deposits during the transportation of oil, oil products and natural gas. It was found that it is advisable to use line heaters with an intermediate heat carrier (water), which is heated during combustion associated (commercial) gas and transfers heat to the process flow through the heat exchange surface for soft heating of viscous oils and oil products to avoid hydrate formation during throttling of natural gas, with the aim of further transportation through pipelines to the place of collection, processing and consumption. A significant part of scientific publications relates to improving the efficiency of such devices with the use of various technological innovations for heat recovery from flue gases, as well as the use of high-quality control systems. On the basis of the analysis of the heater as an object of automation, the main input, disturbing factors and output parameters of control and regulation were established, and the information structure of the heater as a cybernetic system was developed. Based on the equations of the material and heat balance of the apparatus, the mathematical model of the dynamics of the process of heating technological streams has been developed, which includes the differential equations of the heat balance of the product heat exchanger, intermediate heat carrier, flue gases in the gas duct formed during gas combustion. The system of equations is supplemented by equations of heat transfer through two heat exchange surfaces from water to the target product and from flue gases to an intermediate heat carrier. The linearization of the nonlinear components of the developed model in the vicinity of the operating point is carried out. Based on the obtained mathematical description of the heater, a block diagram of the model was synthesized, which shows the relationship of input parameters, control action and output variables in deviations from the base point of the operating mode.

Basic principles of construction of high-quality analytical adaptable control systems for thermal energy processes

The modeling results and industrial tests of a typical automatic control system (ACS) and the proposed invariant cascade ACS are presented. The advantages of structural-parametric optimization methods for creating high-quality control systems for heat-and-power processes have been substantiated. The following algorithm for forming a block diagram of a high-quality invariant cascade SAR is proposed. At the beginning, the structure of the optimal transfer function of the stabilizing regulator is determined as the product of the inverse transfer function of the leading section of the object by a given transfer function of the open system of the internal circuit in the form of an ideal integrating link with one calculated parameter of dynamic tuning, which allows optimally working out both internal disturbances and the task of the stabilizing regulator. Then, the parameters of the dynamic adjustment of the corrective regulator are calculated for optimal processing of the extreme external disturbance. Next, an equivalent external perturbation is isolated without its direct measurement using a complete model of the inertial section of the object. At the same time, the obtained difference between the main adjustable value and the model output is fed to the input of an equivalent external perturbation compensation device implemented in the form of a differentiator, which makes it possible to increase the accuracy and speed of the invariant SAR compared to the standard one. To ensure high quality control over the entire range of load changes, the parameters of the dynamic adjustment of the invariant SAR and the model of the inertial section are adjusted in the load function.

Реализация двухконтурного четырёхканального регулятора для управления процессом стерилизации консервов в промышленном автоклаве

carried out with specified periodic actions, we can distinguish their multiplicity, diversity and originality. However, with regard to the sterilization processes in autoclaves, there is currently no high-quality control system for them, which still determines the relevance of this task. The article offers a selection of criteria that can be applied to the automatic control system, taking into account the specifics of the processes that occur during the sterilization of canned food using an autoclave. This article also discusses the structure of this process using the basics of the theory of automatic control. In addition, it provides a simulation of these processes. In contrast to the existing structures, the proposed automatic control structure is characterized by openness, which increases the design efficiency in the development of such control systems. The basis of this approach in the form of a two-circuit four-channel controller, allows you to improve existing and create new automatic control systems for sterilization plants.

Two-Loop System with Reference Model for Control of Spatial Movement of Cargo Underwater Vehicle

Currently, autonomous underwater vehicles (AUV) are increasingly used to perform tasks related to the maintenance of underwater communications and various underwater production complexes, as well as performing underwater technological operations. To effectively perform these operations, AUV must have high-quality control systems that will ensure their accurate movement both along long spatial trajectories formed during their movement to the objects of work, and when performing complex maneuvers near underwater infrastructure objects. At the same time, the main difficulty that arises in the process of synthesis of AUV control systems is the significant non-linearity of the dynamic models of these control objects, the presence of interactions between their degrees of freedom, as well as the uncertainty and variability of their parameters. In this paper, we propose a method for synthesizing the spatial motion control system of the AUV, which allows us to take into account these negative effects. This system contains two loops. The first loop includes a combined system containing a nonlinear controller to achieve the desired dynamic characteristics of the AUV, when its parameters are equal to the nominal values, and a controller with self-tuning according to the reference model, which provides compensation for an unknown or variable part of the parameters. In this case, the parameters of the controller with the reference model are selected to reduce the possible amplitude of the discontinuous signal for controlling the AUV velocity. The second loop is a non-linear position controller that allows to take into account the dynamic properties of the velocity control loop and the kinematic properties of the AUV. The advantage of the proposed control system in comparison with traditional ones based on PID controllers is a higher control accuracy when moving along complex spatial trajectories, regardless of changes in the AUV parameters. The simulation results confirmed the high efficiency of the synthesized two-loop control system.

КОНЦЕПТУАЛЬНОЕ ПРОЕКТИРОВАНИЕ МЕХАТРОННОГО СТЕНДА ДЛЯ ПРЕДКЛИНИЧЕСКИХ ИСПЫТАНИЙ РОБОТИЗИРОВАННЫХ ПРОТЕЗОВ НИЖНИХ КОНЕЧНОСТЕЙ

Over the past several years, the first real prototypes of robotic prostheses have been developed in Russia, but they still lose competition to the best foreign designs and are practically not in demand in the domestic market of assistive devices. One of the reasons preventing this is the absence in Russia of stands for certification tests of robotic prostheses. In addition, the use of such stands at the design stage would significantly simplify the solution of the problem of synthesizing high-quality control systems and would not require the participation of disabled volunteers for their testing and adjustment. However, there are currently no analogues of such test benches in Russia. This paper describes a conceptual version of a mechatronic stand-simulator capable to simulate biosimilar movements of a human lower limb in various modes of physical activity under variable environmental parameters in order to adjust parameters, laboratory and preclinical tests of structures and control systems of active lower limbs prostheses and their modules. The stand can be easily upgraded for certification testing of robotic lower limb prostheses.

Factors associated with blood cord unit bankability: an analysis of a 15-year-long case series.

Blood banking is a long and complex process requiring an accurate screening of potential donors and high-quality control systems. Previous studies in literature investigated factors potentially determining a higher cell levels with the aim of optimizing donors' selection and improving banking process. This study aims to identify factors associated with the concentration of stem cells in umbilical cord blood, so increasing the probability of bankability, focusing on the possible implications in terms of obstetric and resources management. This is a retrospective study conducted in the Obstetric Units of two Italian Hospitals in Montebelluna and Castelfranco Veneto. Study has been conducted on cord blood units banked between 1999 and 2015. Data on medical histories and clinical characteristics of mother and baby have been retrieved via a retrospective examination of medical records. A total of 869 cord blood units were studied. At multivariable analysis, in agreement with literature, birthweight and placental weight have been found to be associated with higher concentration of total nucleated cells. As additional factor, amount of fluid infused was associated with cord blood units' count. This study is the first one to clearly identify the role of fluid infusion on cord blood units' counts in addition to placental weight and delivery. Some non-modifiable features can help in predicting bankability from pre-natal aspects to factors more related with obstetric management is suggested.

Synthesis of a fractional-order PIλDμ-controller for a closed system of switched reluctance motor control

The relevance of creating high-quality control systems for electric drives with a switched reluctance motor (SRM) was substantiated. Using methods of mathematical modeling, transient characteristics of the process of turn-on of SRMs with various moments of inertia were obtained. Based on analysis of the obtained transient characteristics, features of the SRM turn-on process determined by dynamic change of parameters of the SRM during its turn-on were shown. Low accuracy of SRM identification using a fractionally rational function of rat34 class was shown. Regression coefficient of the resulting model was 85 %. Based on analysis of transient characteristics of the SRM turn-on process, a hypothesis was put forward about the possibility of identifying the SRM by means of a fractional-order transfer function. Using the methods of mathematical modeling, transient characteristics of the process of turning-on the SRMs with various moments of inertia were obtained. Using the FOMCON MATLAB Toolbox, identification of the SRM turn-on process with the help of a fractional-order transfer function of second order was performed. Regression coefficient of the resulting model was 93–96 %. For the obtained fractional-order transfer functions, a method of synthesis of a fractional-order PI λ D μ controller optimized in terms of minimum integral square error of the transition function of the closed system of fractional-order control of objects was implemented. The FOMCON MATLAB Toolbox was used for synthesis of the PI λ D μ controller. Comparative analysis of the SRM turn-on processes in both open and closed control systems with a classical integer-order PID controller and with a fractional-order PI λ D μ controller was made. Use of the fractional-order PI λ D μ controller in comparison with the classical integer-order regulator makes it possible to reduce overshoot from 13.3 % to 2.64 %, increase speed of the closed ACS, decrease regulation time from 1.48 s to 0.53 s while reducing variability of transient characteristics. The study results can be used to improve performance of closed systems for controlling angular velocity of the SRM

Do SOX 404 Control Audits and Management Assessments Improve Overall Internal Control System Quality?

ABSTRACTWe address whether SOX 404(b) internal control audits under two auditing standards regimes and SOX 404(a) management assessments are associated with improved internal control system quality, an important and largely unstudied potential benefit. In 2013, the PCAOB disclosed that 15 percent of inspected control audits were ineffective, suggesting that the current control auditing standard may not be sufficient to induce implementation of high-quality control systems. We use an indirect measure of internal control system quality—future unaudited accruals quality—to proxy for internal control quality because sustained internal control improvements should be exhibited in future quarterly financial reports unaltered by contemporaneous financial statement audits. We find that internal control audits initially provided internal control quality benefits. After the 2007 auditing standards change, internal control quality deteriorated for ICFR audited versus unaudited firms. Finally, we find limited evidence that management assessments affect internal control quality. Results indicate that recent PCAOB concerns may have merit.Data Availability: Data are publicly available from the sources identified in the text.

Experience in Developing a Robot Control Software

This article presents an experience report in using the UML-driven development process to develop an object-oriented control software for a Sony AIBO robot. The entire project was a great learning experience for all the team members and we found the methodologies we used very effective in helping us design and develop a high-quality control system. We also feel that other software developers and practitioners, especially those developing robotic and embedded control software, would benefit from the experience and observations reported in this article.

Automation of a Petroleum Refinery Wastewater Treatment Plant:A Case Study

Abstract Historically, automation was not considered for wastewater treatment plants because it did not significantly affect operating costs, and manual plant operation was considered acceptable. Despite past practices, the BP Oil Refinery at Marcus Hook, Pennsylvania set a new standard when they began upgrading their wastewater facility in 1985. By automating the plant, they ensured safe, reliable operation with minimum labor requirements, process optimization, and long-term reductions in operating costs. Major design features included: a distributed computer control system with monitoring and supervisory capabilities; high-quality control system instruments; control system components; and redundancy and backup to support operation if a component or power failure occurs. In addition, design control philosophies remained consistent from predesign to startup. This advanced wastewater treatment plant can serve as a model for automation of future industrial treatment facilities.

High Quality Control in Hot Strip Mill

Construction on a new 1840 mm hot strip mill, at Nippon Steel’s Hirohata Works, began in June of 1982. This mill, replacing the existing mill, went into commercial operation on August 1, 1984. The mill’s high quality control systems have enabled us to achieve a high degree of accuracy in a number of areas, including, strip thickness, or strip crown and shape. The author and his team have developed an absolute mode AGC system that has allowed them to attain a greatly high degree of thickness accuracy for the full strip length. The system is comprised of four main subsystems organically combined, including several advanced techniques such as non-interferization between thickness and shape, a looper control of the optimum regulator type. Thickness accuracy has reached its highest level.