Automatic Control Mode Research Articles

Effect of water chemistry upsets on the dynamics of corrective reagent dosing systems at thermal power stations

Typical disturbances in the dynamics of a corrective reagent dosing system under unsteady-state conditions during the unsatisfactory operation of a chemical control system with some water chemistry upsets at thermal and nuclear power stations are considered. An experimental setup representing a physical model for the water chemistry control system is described. The two disturbances, which are most frequently encountered in water chemistry control practice, such as a breakdown or shutdown of temperature compensation during pH measurement and an increase in the heat-transfer fluid flow rate, have been modeled in the process of study. The study of the effect produced by the response characteristics of chemical control analyzers on the operation of a reagent dosing system under unsteady-state conditions is important for the operative control of a water chemistry regime state. The effect of temperature compensation during pH measurement on the dynamics of an ammonia-dosing system in the manual and automatic cycle chemistry control modes has been studied. It has been demonstrated that the reading settling time of a pH meter in the manual ammonia- dosing mode grows with a breakdown in temperature compensation and a simultaneous increase in the temperature of a heat-transfer fluid sample. To improve the efficiency of water chemistry control, some systems for the quality control of a heat-transfer fluid by a chemical parameter with the obligatory compensation of a disturbance in its flow rate have been proposed for use. Experimental results will possibly differ from industrial data due to a great length of sampling lines. For this reason, corrective reagent dosing systems must be adapted to the conditions of a certain power-generating unit in the process of their implementation.

Personalized heating – Comparison of heaters and control modes

Personalized conditioning systems represent a promising solution to two major challenges in building industry – high energy consumption of the buildings and still only mediocre thermal comfort. These systems create a microenvironment adapted for each user. Therefore, individual demands for thermal comfort can be met and energy can be saved due to higher effectiveness compared to the traditional HVAC systems. This study investigates two aspects of personalized heating – effectiveness of different heaters and impact of different control modes. Personalized heating system consisting of a heated chair, a heated desk mat, and a heated floor mat was tested with 13 test subjects in a climate chamber under operative temperature of 18 °C. The heaters were tested separately and in combination as user controlled. Furthermore, the complete system was tested with fixed setting and automatic control using hand skin temperature as a control signal. The heated chair and the heated desk mat as well as the complete system significantly improved thermal comfort, while the heated chair was found to the most effective heater. The automatic control mode could provide the same level of thermal comfort as user control in this study.

First results of the integration of a dose monitoring system in the National Breast Screening Program

To demonstrate how a PACS integrated dose monitoring system, Gray Detector, can help to monitor client dose in a breast screening program, ultimately facilitating the optimisation of acquisition parameters in order to enhance image quality and minimise the dose BreastCheck, The National Breast Screening Program evaluated the RIS-PACS integrated dose monitoring system Gray Detector. For each projection of a screening examination, the displayed average glandular dose (AGD), compression force, compressed breast thickness, selected automatic exposure control (AEC) mode, kV and mAs were recorded. Preliminary data have been collected for three months which have enabled comparison of a number of mammography system types and comparison between systems of the same type, in terms of dose, compression force and other key characteristic parameters. Patient dose data collected so far confirm the results of our annual dose survey. All the mammography systems were monitored on a daily basis. The daily presentation of data provides a useful QA tool, highlighting potential problems with individual mammography systems and illustrating the dependency of client dose on other clinical parameters such as compressed breast thickness and compression force. This will enable standardisation of the acquisition technique in order to reduce client dose and optimize the image quality. A summary of these preliminary results will be presented. The Gray Detector software provides useful functionality for monitoring key parameters of the breast screening examination including in particular, the AGD which may be used to monitor and improve clinical quality performance in the screening program. To demonstrate how a PACS integrated dose monitoring system, Gray Detector, can help to monitor client dose in a breast screening program, ultimately facilitating the optimisation of acquisition parameters in order to enhance image quality and minimise the dose BreastCheck, The National Breast Screening Program evaluated the RIS-PACS integrated dose monitoring system Gray Detector. For each projection of a screening examination, the displayed average glandular dose (AGD), compression force, compressed breast thickness, selected automatic exposure control (AEC) mode, kV and mAs were recorded. Preliminary data have been collected for three months which have enabled comparison of a number of mammography system types and comparison between systems of the same type, in terms of dose, compression force and other key characteristic parameters. Patient dose data collected so far confirm the results of our annual dose survey. All the mammography systems were monitored on a daily basis. The daily presentation of data provides a useful QA tool, highlighting potential problems with individual mammography systems and illustrating the dependency of client dose on other clinical parameters such as compressed breast thickness and compression force. This will enable standardisation of the acquisition technique in order to reduce client dose and optimize the image quality. A summary of these preliminary results will be presented. The Gray Detector software provides useful functionality for monitoring key parameters of the breast screening examination including in particular, the AGD which may be used to monitor and improve clinical quality performance in the screening program.

Creating an automatic control system for industrial air conditioners

The study suggests an automatic temperature control system for more than one industrial air conditioner since industrial equipment is much more complicated than household one and often requires working out individual projects. The mathematical modelling of a water cooler of an industrial air conditioner is based on transfer functions that allow an accurate description of the object of control. This mathematical model reflects the real nature of changes in air parameters and can be used in the development of other temperature control devices. The devised scheme simulates the behaviour of control systems for industrial air conditioners. The scheme of the control system is implemented in the Simulink package, MATLAB. It includes two air conditioners and operates in three modes that are determined by temperature ranges. The research reveals the operational features of the automatic control system for two industrial air conditioners, reflecting the nature of changes in the air temperature and experimental values of the system operation time. The versatile nature of the new system distinguishes it among other automatic control systems and makes it valuable for further research in this area. The possibility of adjustment to air conditioning peculiarities allows creating an improved control system that would resolve the problem and ensure an effective control of air conditioners. The research findings can be used in further individual projects of air conditioning of industrial buildings, which is likely to provide high-quality automatic air temperature control modes.

ABT Based Load Frequency Control of Interconnected Power System

This article presents a frequency dependant price signal based new automatic generation control scheme for an interconnected power system. A two-area interconnected power system model consisting of four thermal generating stations in each area is considered under this work. All generators are operating with primary/conventional automatic generation control scheme or availability based tariff automatic based generation control scheme and each generator is owned by a separate generation company. The implementation of an availability based tariff based automatic generation control scheme is carried out for switching operations between automatic generation control and non-automatic generation control mode, which is based on the difference of the generator's marginal cost and real time frequency dependent price of unscheduled generation. The performance of generators employing primary/conventional automatic generation control scheme or availability based tariff based automatic generation control scheme has been investigated. A commercial case study is carried out to demonstrate effectiveness of the proposed control scheme.

PATIENT DOSE DURING THERAPEUTIC ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY PROCEDURE.

Endoscopic retrograde cholangiopancreatography (ERCP) is a standard technique for the diagnosis and treatment of disorders of the pancreas or bile ducts. The aim of this study was the measurement of the radiation dose to patients during therapeutic ERCP procedures, in order to estimate the patient effective dose (ED). Fifteen patients were studied using a fluoroscopy system equipped with automatic brightness control and pulse fluoroscopy mode. Fluoroscopy time (FT), cumulative dose (Ka,r) and air kerma-area product (PKA) were collected for ERCP procedures. The ED was calculated from PKA values. The FT was ranged from 0.68 to 5.57 min, with the mean value of 2.50 min; the Ka,r was ranged from 2.22 to 19.10 mGy, with the mean value of 7.71 mGy; and the PKA was ranged between 0.59 and 5.10 Gycm2, with the mean value of 2.03 Gycm2. The ED ranged from 0.11 to 0.97 mSv, whilst the mean and median ED values were 0.39 and 0.32 mSv, respectively. FT and radiation dose to the patients were either comparative or significantly lower than those previously reported.

Hop-Picking Machine Control Based on Capacitance Throughput Sensor

Abstract. Previous studies have shown that capacitance throughput units can be used as a source of output voltage signal for satisfactory hop-picking machine throughput control. This study investigated the possibility of capacitance throughput sensor integration into some appropriate location of a PT-30 stationary hop-picking machine, the possibility of its calibration, the possibility of control procedure development, and its performance verification under operational conditions. A capacitance throughput sensor was integrated into the pocket belt conveyor that transports freshly picked hop material to the separation part of the machine. Control of the frequency converter, which powers the electric motor of the pocket belt conveyor, was realized by a simple controller application, with a graphic touch panel serving as an interface with the machine operator. The mathematical model of capacitance sensor sensitivity distribution helped us to better understand its function in its practical application on a pocket belt conveyor with metal pockets. A linear dependence of sensor output voltage on wet hop material throughput was determined for a throughput range from 0.38 to 0.66 kg s -1 with a suitable coefficient of determination (R 2 = 0.98). Based on calibration results and harvesting losses measurement, a simple mode of automatic control algorithm was developed. The functioning of the control system was observed for 2 h (picking of hop plants from one trailer) during an ordinary harvesting day with the aim to verify its performance. In the case of throughput automatic control usage, the periods with high material throughput rates (higher than 0.5 kg s -1 ), which are the cause of losses, occurred six times less in comparison with the situation without control. The peaks of harvesting losses dropped from 8% to 4%. The machine operator quickly evaluated this situation and spontaneously started to use the automatic control mode after the control system was installed to the machine.

Airflow Measurement of the Car HVAC Unit Using Hot-wire Anemometry

Thermal environment in a vehicular cabin significantly influence drivers’ fatigue and passengers’ thermal comfort. This environment is traditionally managed by HVAC cabin system that distributes air and modifies its properties. In order to simulate cabin thermal behaviour, amount of the air led through car vents must be determined. The aim of this study was to develop methodology to measure airflow from the vents, and consequently calculate corresponding air distribution coefficients. Three climatic cases were selected to match European winter, summer, and spring / fall conditions. Experiments were conducted on a test vehicle in a climatic chamber. The car HVAC system was set to automatic control mode, and the measurements were executed after the system stabilisation—each case was independently measured three times. To be able to evaluate precision of the method, the airflow was determined at the system inlet (HVAC suction) and outlet (each vent), and the total airflow values were compared. The airflow was calculated by determining a mean value of the air velocity multiplied by an area of inlet / outlet cross-section. Hot-wire anemometry was involved to measure the air velocity. Regarding the summer case, total airflow entering the cabin was around 57 l s -1 with 60 % of the air entering the cabin through dashboard vents; no air was supplied to the feet compartment. The remaining cases had the same total airflow of around 42 l s -1 , and the air distribution was focused mainly on feet and windows. The inlet and outlet airflow values show a good match with a maximum mass differential of 8.3 %.

Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms.

Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to study the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens(®)) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 -34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom ("Laura"), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode. Regarding the BSF, the results achieved may lead to a MGD correction of about 6%, contributing to the improvement of the current guidelines used in these applications. Finally, considering the MC results obtained for the organ dose study, the radiation doses found for the tissues of the body other than the breast were in the range of tens of μSv, and are in part comparable to the ones obtained in standard DM. Nevertheless, in a single DBT examination, some organs (such as lung and thyroid) receive higher doses (of about 9% and 21%, respectively) with respect to the CC DM acquisition. Taking into account an average breast with a thickness of 4.5 cm, the MGDs for DM and DBT acquisitions were below the achievable value (2.0 mGy) defined by the European protocol. Additionally, in the case of a fusion imaging study (DM + DBT), the MGD for a 4.5 cm thick breast is of the order of 1.88 ± 0.36 mGy. Finally, organ dose evaluations underline the need to improve awareness concerning dose estimation of DBT exams for some organs, especially when radiation risk is assessed by using the effective dose.

Design of Monitoring System of Cooling Water System in EAST Neutral Beam Injector

The monitoring system of the cooling water system in EAST Neutral Beam Injector (EAST-NBI) is introduced in this paper. The key heat loading components of the EAST-NBI consist of two ion sources and high-heat-flux components inside the beamline. In order to meet requirements of the water flow inside the key components, the monitoring system of the water cooling system provides functions to configure the water process control parameters, real-time measurement and remote control. The water quality process control is running in the automatic control modes including the working mode and standby mode in accordance with the operational parameters. The water cooling system is operated in the remote control room by using graphical user interfaces which visually reflect the working status of the cooling water system. The experimental results show that the hardware and software architecture of the monitoring system meets the water quality process requirements and provides reliable remote monitoring functions.

A thermal management device for a lower-limb prosthesis

Excessive heat and the resulted perspiration within a prosthetic socket were the most common causes for reporting a reduced quality of life for prosthesis users. This paper presents a novel thermal management device to maintain a constant skin temperature for a lower-limb prosthesis. To decrease the prosthetic socket's thermal resistance, heat pipes were used to concentrate heat flux from the simulated skin surface to a cooling region on the outer surface of the socket where a compact heat sink was attached. A small fan was used to convect heat from the heat sink to the ambient surroundings. Thermal resistance of the cooling device was adjusted to match various thermal loads by changing the fan power. Experiments showed that cooling capacity of the prototype device ranges from 2.1 W to 7.0 W at an ambient temperature of 23.0 °C. The automatic control mode to maintain a constant skin temperature was also demonstrated. Further analysis showed that the device can potentially maintain a constant skin temperature for a thermal load as large as 9.4 W. The compact size, quiet operation and heat removal capability make the device suitable for maintaining a comfortable and healthy thermal environment inside the prosthesis socket.

Modelling of thermal power plant for the needs of Q-V characteristic control on HV bus bars

In this paper, a mathematical model of the thermal power plants TENT A and TENT B, developed for voltage and reactive power control simulation purposes, is presented. The model is developed using the Simulink/Matlab program platform. All important elements, such as synchronous generator, step-up transformer, turbine and governor, excitation system, automatic voltage regulator (ARN) and the network, connected to the power plant's bus bars, are modelled with the complexity level required for studying the problems of interest. In the first part, a review of the hierarchical voltage control in the system is given, because the coordinated reactive power regulator (GRRS) has to be embedded in future processes of voltage control automatisation on higher levels and 'smart' control in the power system. For the needs of studying the HV bus bars voltage control, as well as reactive power allocation within the power plant in manual and automatic control mode, a series of simulations was performed. For verification purposes, the simulation results are compared to the on-site measurements. An excellent match of simulated and recorded results is achieved.

Setting of the Operating Conditions of Stereo CCTV Cameras by Weather Condition

A wide variety of image application methods, such as aerial image, terrestrial image, terrestrial laser, and stereo image point are currently under investigation to develop three-dimensional 3D geospatial information. In this study, matching points, which are needed to build a 3D model, were examined under diverse weather conditions by analyzing the stereo images recorded by closed circuit television (CCTV) cameras installed in the U-City. The tests on illuminance and precipitation conditions showed that the changes in the number of matching points were very sensitively correlated with the changes in the illuminance levels. Based on the performances of the CCTV cameras used in the test, this study was able to identify the optimal values of the shutter speed and iris. As a result, compared to an automatic control mode, improved matching points may be obtained for images filmed using the data obtained through this test in relation to different weather and illuminance conditions.

Temperature control during therapeutic hypothermia for newborn encephalopathy using different Blanketrol devices.

Therapeutic hypothermia improves the survival and neurodevelopmental outcome of infants with newborn encephalopathy of a hypoxic-ischemic origin. The NICHD Neonatal Research Network (NRN) Whole Body Cooling trial used the Cincinnati Sub-Zero Blanketrol II to achieve therapeutic hypothermia. The Blanketrol III is now available and provides additional cooling modes that may result in better temperature control. This report is a retrospective comparison of infants undergoing hypothermia using two different cooling modes of the Blanketrol device. Infants from the NRN trial were cooled with the Blanketrol II using the Automatic control mode (B2 cohort) and were compared with infants from two new NRN centers that adopted the NRN protocol and used the Blanketrol III in a gradient mode (B3 cohort). The primary outcome was the percent time the esophageal temperature stayed between 33°C and 34°C (target 33.5°C) during maintenance of hypothermia. Cohorts had similar birth weight, gestational age, and level of encephalopathy at the initiation of therapy. Baseline esophageal temperature differed between groups (36.6°C ± 1.0°C for B2 vs. 33.9°C ± 1.2°C for B3, p<0.0001) reflecting the practice of passive cooling during transport prior to initiation of active device cooling in the B3 cohort. This difference prevented comparison of temperatures during induction of hypothermia. During maintenance of hypothermia the mean and standard deviation of the percent time between 33°C and 34°C was similar for B2 compared to B3 cohorts (94.8% ± 0.1% vs. 95.8% ± 0.1%, respectively). Both the automatic and gradient control modes of the Blanketrol devices appear comparable in maintaining esophageal temperature within the target range during maintenance of therapeutic hypothermia.

Hierarchical Operation of Water Level Controllers: Formal Analysis and Application on a Large Scale Irrigation Canal

We introduce a hierachical controller, the purpose of which is to speed up the water delivery process as compared to the standard method applied currently in the field. The lower layer of the hierarchical control consists of local proportional integral filter controllers (PIF controllers) for upstream control at each gate; specifically they are proportional integral controllers with a low-pass filter. In contrast, the higher layer is composed of a centralized model-based predictive controller, which acts by controlling the head gate and by coordinating the local PIF controllers by modifying their setpoints when needed. The centralized controller is event-driven and is invoked only when there is a need for it (a water delivery request) and as such it contributes scarcely to the communication burden. The scheme is robust to temporary communication losses as the local PIF controllers are fully able to control the canal in their normal independent automatic upstream control mode until the communication links are restored. We discuss the application of the hierarchical controller to a precise numerical model of the Central California Irrigation District Main Canal. This shows the improved performance of the new hierarchical controller over the standard control method.

Key Technologies of the Embedded Deformation Measuring Control System Based on SOPC

Deformation measurement is an important content of engineering surveying and the main objects of the deformation measurement are civilians, industrial buildings, precision engineering, large dam, bridge and the earth's crust deformation of rock mass. Deformation measurement aims to obtain the deformation data in the process of displacement deformation, and to get the deformation of the status, trend and possible results through the analysis of these data. The existing automatable solution for measuring the deformation all adopt the 3-dimension displacement test, which based on high precision total station, unattended, automatic data acquisition and transmission control mode.

The Design of Rudder System Simulation Device

This paper designs a ship rudder system simulation device in order to serve the research of ship control better with the proportion of a real marine hydraulic rudder system, which can complete closed-loop experiments in the lab with the steering system. The rudder system simulation device mainly includes two parts, electric control system which uses PLC as core control unit, hydraulic system, and it can achieve both manual and automatic operation control mode.

Design and Simulation of Automatic Transition Control System for Helicopter Based on Model Reference Adaptive

In order to achieve the anti-submarine capabilities of helicopter, it is essential to design the automatic transition controller. According to the basic requirements of automatic transition control mode and the rational use of limiter and exponential law, the control loop of altitude and ground speed is designed. And the control between the two channels must be coordinated, so that when altitude descends to hovering altitude, ground speed close to zero simultaneously. In this paper, the method of model reference adaptive is used to correct the altitude deviation which makes altitude trajectory followed the set rules. The simulation shows that the method can make the altitude trajectory track the desired trajectory in good.

Исследование сверхмощных дуговых сталеплавильных печей с тиристорным регулятором напряжения в промежуточном контуре печного трансформатора

This article presents the possibility of secondary voltage thyristor control of the furnace transformer EAF-180 JSC “MMK”. The negative influence of dispersion current electric arc by an amount of active power injected into the furnace. Based on the research, the authors propose a new concept of building a combined system of automatic control mode electric arc furnace, providing increase its stability.

Study on Flue Gas Desulfurization Process Control System Based on Coupling Decoupling Control

The coupling decoupling control system was presented to realize the requirement of the flue gas desulfurization (FGD), to solve the multivariable control problem in this process control system. The FGD experiment control system was designed, the spray flow was controlled by manual and automatic control mode. After the process control flow and the coupling decoupling control principle were studied, the feed-forward compensation control method was simulated. Results show that the decoupling control method could solve the multivariable control problem, with a good anti-interference capacity, meeting the requirement of FGD process control.