Control Philosophy Research Articles

Distributed Automatic Control System Supported by RFID Applied to a Logistic Centre Test Bench

With the aim of incorporating new techniques and methodologies, this article presents the use of distributed control methods based on Multi-Agent Systems (MAS) enhanced with Radio-Frequency Identification (RFID). RFID is here applied as the technological base of a new generation of automatic distributed control systems in which traceability and tracking are key characteristics. The research on this area has grown rapidly in late years. However, the lack of alignment and visibility between the management and control system has hardly been explored. This paper shows a way to face this problem, and also presents the application and analysis of the proposed control philosophies in an experimental platform, controlled by a network of programmable logic controllers (PLCs).

Tracking Control of a Closed-Chain Five-Bar Robot With Two Degrees of Freedom by Integration of an Approximation-Based Approach and Mechanical Design

The trajectory tracking problem of a closed-chain five-bar robot is studied in this paper. Based on an error transformation function and the backstepping technique, an approximation-based tracking algorithm is proposed, which can guarantee the control performance of the robotic system in both the stable and transient phases. In particular, the overshoot, settling time, and final tracking error of the robotic system can be all adjusted by properly setting the parameters in the error transformation function. The radial basis function neural network (RBFNN) is used to compensate the complicated nonlinear terms in the closed-loop dynamics of the robotic system. The approximation error of the RBFNN is only required to be bounded, which simplifies the initial "trail-and-error" configuration of the neural network. Illustrative examples are given to verify the theoretical analysis and illustrate the effectiveness of the proposed algorithm. Finally, it is also shown that the proposed approximation-based controller can be simplified by a smart mechanical design of the closed-chain robot, which demonstrates the promise of the integrated design and control philosophy.

A Review of Social Media Use in E-Government

In the past few years, e-government has been a topic of much interest among those excited about the advent of Web 2.0 technologies. This paper reviews the recent literature concerning Web 2.0, social media, social networking, and how it has been used in the public sector. Key observations include literature themes such as the evolution of social media case studies in the literature, the progress of social media policies and strategies over time, and social media use in disaster management as an important role for government. Other observations include the lack of a tangible goal for e-government, and the idea that significant change is still needed in government culture, philosophy of control, and resource management before broad sustainable success can be achieved in the use of social media.

Transient analysis of integrated Shiraz hybrid solar thermal power plant

Abstract Shiraz solar thermal power plant is designed for 250 kW power supply during available sun radiation. It is decided to promote the field of collectors by installing a large parabolic collector and combining the system with a 500 kW hybrid boiler. For the new integrated configuration, thermodynamic analysis is required for engineering design and evaluating thermal performance. For the new system, transient simulation is performed under different working conditions. In the plant, each component is simulated transiently, by considering initial condition and capacity rate of the component as well as all the connecting pipes and instruments. Results of the simulation for thermal performance are compared with field experimental measurements for several periods. Taking into account the thermodynamic concepts and the results of numerical and experimental analysis, the best operation strategies are selected for optimum performance and control philosophy based on the new integrated collector.

Transient simulation for developing a combined solar thermal power plant

In the present article, performing a transient simulation, power expansion of a solar power plant by integrating a new collector and an auxiliary boiler is studied. The new system consists of an oil cycle, a steam cycle and a new extra oil cycle. For analysis, a computer code is developed and experiments are performed to validate the simulation program. Thermal modeling is employed to select the best capacity of different components and operational control philosophy of the new developed power plant system. Based on the selected conditions, annual power generation of solar part and fossil section are determined and compared with conventional power plants using coal and natural gas. From the results it is shown that the considered method of integration can be used for all fossil fuel power plants to reduce fuel consumption by utilizing parabolic collectors for electricity generation. Comparison of the new system with previous arrangement illustrates that various integration schemes can be easily simulated and an appropriate system to satisfy the main design objectives can be chosen. The advantages of using a new external loop to integrate parabolic solar collectors into the previously constructed fossil fuel system are also discussed.

Performance Evaluation of Homing Guidance Methods

A guided missile must be endowed with sufficient intelligence to acquire information for keeping it on course to the target, whether it was stationary or mobile. The guidance commands are generated to control the missile motion relative to target in accordance to the observed and estimated parameters for target motion. The necessity for guiding the missile motion is given by (1) the need to compensate for the non-standard conditions of the medium, technology, propulsion for the achievement of the desired accuracy, especially at greater ranges, (2) the need of reacting on the target maneuver during its flight, and (3) the need for conducting fire behind terrain undulations and artificial obstacles. According to the guidance and control philosophy utilized to control the missile motion and the location of the guidance computer, there are five types of guidance: Homing guidance, Autonomous guidance, Beam rider guidance, Command guidance and Combined guidance systems. The Homing Guidance may be active using onboard transceiver to provide the guidance signals, semi-active which combines an onboard receiver with external illuminator and passive which home on energy generated by the target. The performance of the guidance system is dependent upon the utilized guidance method which constraints the vehicles attitude during its flight. Therefore, this paper is devoted to evaluate the performance of homing guidance methods via the solution of the derived equations of c.g. motion in conjunction with ideal bond equations either numerically or analytically. The guidance performance is analyzed via flight path parameters obtained from the equations' solution. Note that the analytical solution can be very complex unless some simplifying assumptions are considered such as planer motion, constant speeds, etc. Then, the obtained equations are programmed as functions within the MATLAB environment (or any high level language) and the simulation is conducted using different engagements’ scenarios. The results justify the capabilities of each guidance method according to the engagement scenario and it will be of great value to young researchers and designers.

Agent-based decision-making process in airport ground handling management

Recent research on highly distributed control methods has produced a series of new philosophies based on negotiation, which bring together the process engineering with computer science. Among these control philosophies, the ones based on Multi-agent Systems (MAS) have become especially relevant to address complex tasks and to support distributed decision making in asset management, manufacturing, and logistics. However, these MAS models have the drawback of an excessive dependence on up-to-date field information. In this work, a theoretical and experimental MAS, called MAS-DUO, is presented to test new strategies for managing handling operations supported by feedback coming from radio frequency identification (RFID) systems. These strategies have been based on a new distributed organization model to enforce the idea of division between physical elements and information and communication technologies (ICT) in the product scheduling control. This division in two platforms simplifies the design, the development, and the validation of the MAS, allowing an abstraction and preserving the independency between platforms. The communication between both platforms is based on sharing the parameters of the Markov reward function. This function is mainly made up of the field information coming from the RFID readers incorporated as the internal beliefs of the agent. The proposed MAS have been deployed on the Ciudad Real Central Airport in Spain in order to dimension the ground handling resources.

Distillation pressure control troubleshooting—The hidden pittfalls of overdesign

The operating pressure of a distillation column is one of the main handles with which to control and optimise separation as it affects most other parameters as well as the overall stability of the column. It is therefore one of the most important parameters to control. Controlling a distillation column, designed to be operated under a vacuum, at the intended operating pressure can prove to be much more difficult than for positive pressure columns especially during the initial start-up of the column. Determining the cause of pressure instability can be a daunting task as the column will most likely be under turndown conditions, the inventory might differ from the intended composition, the control loops will be in manual or not tuned yet or the cause might even be from an equipment design perspective. During the initial start-up of a vacuum operated distillation column several problems were encountered that prohibited the column from being operated at its intended pressure. This caused severe instabilities in the column and also affected the downstream sections of the plant. This paper focuses on these problems and the troubleshooting to determine the causes of the pressure instability. During troubleshooting a number of key factors that contributed to the pressure instability were identified, with the main cause being the design and expected air ingress into the column. This influenced the design of several pieces of equipment in and around the column. A deviation from the design air ingress meant that several design parameters had to be re-evaluated in order to eventually reach the intended operating pressure. A conventional pressure control philosophy was implemented, but changes to this were required in order to achieve the necessary stability in the column. The improved control philosophy has several benefits, such as a reduced number of variables to be manipulated by the operator, smoother change over between the primary pressure controller and the setpoint high controller, as well as optimising the product losses to the vacuum system.

CO2 capture with CaO in a 200 kWth dual fluidized bed pilot plant

Abstract The Calcium Looping (CaL) process using CaO as sorbent for capturing CO 2 from flue gases is a promising postcombustion CO 2 -capture technology that is economically competitive with other capture technologies with an overall increased output in electric power and a low electric efficiency penalty associated with CO 2 capture. The process can be realized in a Dual Fluidized Bed (DFB) system utilizing a Circulating Fluidized Bed (CFB) reactor as carbonator operating at 600–700 °C and a second CFB as regenerator operating at temperatures between 850–950 °C. The separation of CO 2 from the flue gas takes place through the carbonation reaction (CaO+CO 2 →CaCO 3 ). The regeneration of the sorbent is realized via the reverse reaction in the regenerator at higher temperatures. The feasibility of the CaL process has already been shown at IFK, University of Stuttgart on a lab-scale size. In order to investigate the calcium looping process using real combustion flue gas and to evaluate the process on a long-term basis, a 200 kWth pilot plant has been built at IFK. This paper delineates the design of the pilot plant to capture over 90% CO 2 and provides an overview of the main components and the control philosophy. First results from the successful commissioning of the pilot plant are also shown.

INGENIERÍA DE CONTROL Y PROTECCION DE SUBESTACIONES ELECTRICAS

ABSTRACT This paper presents the results of a review on different engineering projects for the control and relaying of electrical substations. A general introduction to substations and their functions within a power system is given, along with a description of their control system and philosophy. In the work, different projects have been analyzed and, as a result, the study has identified the aspects to be considered in a good engineering project, adapted to today’s complex requirements on the automation and relaying of electrical substations, and the documentation to include. The paper concludes with a discussion on future developments in the control engineering of these facilities.

Models for local implementation of comprehensive cancer control: meeting local cancer control needs through community collaboration

The comprehensive cancer control approach is used by state, tribes, tribal organizations, territorial and Pacific Island Jurisdiction cancer coalitions to spur local implementation of cancer plans to reduce the burden of cancer in jurisdictions across the country. There is a rich diversity of models and approaches to the development of relationships and scope of planning for cancer control activities between coalitions and advocates in local communities. The national comprehensive cancer control philosophy provides an operational framework while support from the Centers for Disease Control and Prevention enables coalitions to act as catalysts to bring local partners together to combat cancer in communities. This manuscript describes multiple characteristics of cancer coalitions and how they are organized. Two models of how coalitions and local partners collaborate are described. A case study method was used to identify how five different state and tribal coalitions use the two models to organize their collaborations with local communities that result in local implementation of cancer plan priorities. Conclusions support the use of multiple organizing models to ensure involvement of diverse interests and sensitivity to local cancer issues that encourages implementation of cancer control activities.

Design and Implementation of Two Axis Tool Table Control

This paper presents the software implementation of a feedback control for the two axes of an XY table and the simulations of motor X and motor y velocity responses to the specific step inputs. The object of the software is to guide the “tool point” around the outside edge of a planar “workpiece” under computer control. PWM method and P control philosophy are used in the control. By means of least-squares estimation, the values of coefficients in the discrete modes for the controlled motors are determined. The results show that the control strategy is practical and the simulations are valid.

Damage control philosophy in polytrauma

Severe traumatic injury is a public health care problem; with injuries accounting for 12% of the global mortality. Continued improvement in the survival of severely injured trauma patients is a paramount goal. Bailout/damage control surgery following trauma has developed as a major advance in surgical practice in the last twenty years. The principles of damage control surgery defied the traditional surgical teaching of definitive operative intervention and were slow to be adopted. Currently, damage control surgery has been successfully utilized to manage traumatic thoracic, abdominal, extremity, and peripheral vascular injuries. In addition, damage control surgery has been extrapolated for use in general, vascular, cardiac, urologic, and orthopaedic surgery. Stone et al were the first to describe the “bailout” approach of staged surgical procedures for severely injured patients. This approach emerged after their observation that early death following trauma was associated with severe metabolic and physiologic derangements following severe exsanguinating injuries. Profound shock along with major blood loss initiates the cycle of hypothermia, acidosis, and coagulopathy. During the 1980s, hypothermia, acidosis, and coagulopathy were described as the “trauma triangle of death” which makes the prolonged and definitive operative management of trauma patients dangerous. The management technique, now described as “damage control” by Rotondo et al, involves a multiphase approach, in which reoperation occurs after correction of physiologic abnormalities.

Are safety and reliability two contradicting parameters?

AbstractThe nameplate capacity of chemical plants, and in particular ammonia plants, has been steadily increasing over the past 30 years. As the plant capacity grows, so does the cost of an unscheduled production stop. Furthermore, the safety awareness in chemical complexes has been steadily increasing, resulting in more complex trip systems. This article analyzes the complexity of the control system using tools known from safety integrity level (SIL) analysis, and it describes how the plant availability and reliability may be affected by the selection of different control philosophies. This study concludes that a two out of three voting trip system is a sound investment in a modern plant, and that an even more advanced system will add benefit to the plant owners. © 2010 American Institute of Chemical Engineers Process Saf Prog, 2010

A Novel Space Vector Pulse Width Based High Performance Variable Structure Direct Torque Control Evaluation of Induction Machine Drives

In this study, direct torque control (DTC) of induction motor is evaluated based on space vector modulation (SVM).DTC is a method to control machine with utilizing torque and flux of motor controlled.Direct Torque Control (DTC) is known to produce fast response and robust control in ac adjustable speed drives. However, in the steady-state operation, notable torque, flux and current pulsations occur. In this paper, a new direct torque and flux control strategy based on Variable-Structure Control (VSC) and Right Aligned Space Vector Modulation (RASVM) is proposed for sensorless induction motor drives. The principles of variable structure control (Sliding mode controller), DTC and less commutation space vector modulation are combined to ensure high performance operation, both in the steady state and under transient conditions. Three new VSC schemes are designed following the DTC voltage control philosophy. SVM-DTC is a technique to reduce the ripple. SVM techniques have several advantages that are offering better DC bus utilization, lower torque ripple, lower total harmonic distortion in the AC motor current, lower switching loss, and easier to implement in the digital systems. Simulation results from the classical and improved DTC are presented and compared. Result shows that the torque, flux linkage and stator current ripple are decreased with the improved DTC.

Development of a single stage heat integrated water–gas shift reactor for fuel processing

Compacting of the water–gas shift (WGS) section within a fuel processor for fuel cell based power generation by means of heat integration is presented. The concept of isothermal adiabatic operation is demonstrated. Isothermal adiabatic operation is achieved by dissipating the reaction heat throughout the catalyst support structure by means of thermal conduction. Thus the reactor overall behaves adiabatically, while the catalyst bed is nearly isothermal, while no active heat exchange with a second medium is applied. The concept allows for a much lower feed temperature. Accordingly, the conventional double staged WGS reactors with intermediate heat exchange can be replaced with a single WGS reactor. Two reactor designs, based on aluminum metal foam and aluminum metal monolith were evaluated. For the design of the isothermal adiabatic reactor, the intrinsic kinetics for a noble-metal WGS catalyst was measured and a power law rate equation was obtained. Isothermal adiabatic operation was approached for the foam, mainly hampered by a troublesome catalyst coating. The monolith allows for a simpler reactor design and its performance agreed well with model predictions. Simulations of the process dynamics further indicate superior performance of the isothermal adiabatic concept compared to the adiabatic concept. This would allow a much simpler control philosophy for the WGS section in a fuel processor.

Monitoring combustion systems using HMM probabilistic reasoning in dynamic flame images

Abstract In this paper, a novel method of on-line flame detection in video is proposed. Processing the data generated by an ordinary camera monitoring scene, it aims to early detect the current state of the combustion system and prevent the system from further degradation and occurrence of failure. Due to the dynamic change of the combustion system, the turbulent flame flicker produces images with different spatial and high temporal resolutions. The proposed method consists of hidden Markov model (HMM) and multiway principal component analysis (MPCA). MPCA is used to extract the cross-correlation among spatial relationships in the low dimensional space while HMM constructs the temporal behavior of the sequential observation. Although the prior process knowledge may not be available in the operation processes, the probability distribution of the normal status can be trained by the images collected from the normal operation processes. Subsequently, monitoring of a new observed image is achieved by a recursive Viterbi algorithm which can find the transition state sequence from series of observed image data. The proposed method, like the philosophy of traditional statistical process control, can generate simple probability monitoring charts to track the progress of the current transition state sequence and monitor the occurrence of the observable upsets. The advantages of the proposed method, data from the monitoring practice in the real combustion systems, are presented to help readers delve into the matter.

Training in the practical application of damage control and early total care operative philosophy – perceptions of UK orthopaedic specialist trainees

Despite improvements in the outcome of individuals sustaining significant injury, the optimum management of fractures in traumatised patients remains an area of debate and publication. There is, however, a paucity of studies regarding the specifics of acquired experience and training of junior orthopaedic surgeons in the practical application of these skills. Our null hypothesis is that, despite alteration in surgical training, the perceived confidence and adequacy of training of UK orthopaedic specialist trainees in the application of damage control orthopaedics (DCO) and early total care (ETC) philosophy is unaffected. A web-based survey was sent to a sample of orthopaedic trainees. From 888 trainees, 222 responses were required to achieve a 5% error rate with 90% confidence. A total of 232 responses were received. Trainees reported a high level of perceived confidence with both external fixation and intramedullary devices. Exposure to cases was sporadic although perceived training adequacy was high. A similar pattern was seen in perceived operative role with the majority of trainees expecting to be performing such operations, albeit under varying levels of supervision. In a more complicated case of spanning external fixation for a 'floating knee, trainees reported a decreased level of perceived confidence and limited exposure. One-third of trainees reported never having been involved in such a case. In contrast to nationally collated logbook data, exposure to and perceived confidence in managing cases involving ETC and DCO were similar. Despite changes in the training of junior orthopaedic surgeons, trainee-reported confidence and adequacy of training in the practical application of DCO and ETC was high. Exposure to cases overall was, however, seen to be limited and there was a suggestion of disparity between current operative experiences of trainees and that recorded in the national trainee logbook.

Temana Field: A Shift in Sand-Control Philosophy

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper IPTC 12390, "Temana Field Pilot Implementation: A Shift in Sand Control Philosophy To Improve Well Performance," by Wan Amni Bt Wan Mohamad, SPE, Maharon Jadid, SPE, and Mahmoud A. Wahba, SPE, Petronas Carigali Sdn. Bhd., originally prepared for the 2008 International Petroleum Technology Conference, Kuala Lumpur, 3-5 December. The paper has not been peer reviewed. The Temana field consists of unconsolidated reservoirs that require active sand control. The conventional internal-gravel-packed (IGP) technique has been used widely because it has provided a reliable means of abating sand production. These completions, however, have skin factors greater than 15, which increases with time as a result of fines migration into the packed area. In many cases, flow efficiencies were reduced by 70%, which affected well performance severely. Introduction The Temana field was discovered in 1962 and brought on production in 1979. The field is approximately 19 miles west of Bintulu in a water depth of approximately 96 ft. It consists of three hydrocarbon accumulations, Temana west, Temana central, and Temana east. The field has undergone a complex tectonic history and is highly faulted and compartmentalized. The latest development is from the existing Platform A, which penetrates the Temana saddle, in the southeastern part of Temana central. The main reservoir target is the I-65 sand. The sand has a fining-upward log signature with a sharp base at the bottom of the sand. The sand contains light oil of approximately 41.1°API with reservoir pressure of 1,553 psi, average porosity of 26% (oil), and effective permeability of more than 1 darcy. The main drive mechanism of this reservoir is depletion drive, with weak-to-moderate aquifer support. There are seven existing platforms and two additional production-processing-facilities platforms. Approximately 44 out of 74 of the existing oil-producer wells were completed cased hole IGP, and only two wells had premium screens installed in horizontal open holes. On the basis of well-test data for these wells for a similar type of reservoir, the average skin is 10 to 15 and increases to 20 to 30 after several years of production. The average productivity indices (PIs) of these wells ranged between 1 to 20 bbl/(psi-D). Investigation shows that the increasing skin and deterioration in production are a result of fines movements into the gravel-packed sand, and this was aggravated when water broke through. Well-Design Considerations The best standalone screen (SAS) available in the market should be selected for the new Temana wells, considering economics and well deliverability. The well-design team developed a workable solution to be used to minimize various risks. The SAS proposed is the direct wire-wrapped screen (WWS), which is a surface-filtered screen, where plugging tendency is minimized.

Vector control design and experimental evaluation for the brushless doubly fed machine

A new vector control algorithm for the brushless doubly fed machine (BDFM) has been developed. The goal of BDFM control is to achieve a similar dynamic performance to the doubly fed induction machine (DFIM), exploiting the well-known induction motor vector control philosophy. For this purpose, a recently developed unified reference-frame model has been used to develop the vector control strategy. The theoretical considerations for the vector control design, control loops tuning and limits are shown. In addition, practical considerations for the experimental implementation of vector control for the BDFM are shown. Experimental results in a machine prototype confirm the good dynamic performances of this type of control.