Networked control with time delay compensation scheme based on a smith predictor for the activated Sludge Process

In thispaper, a Smith predictor compensation scheme is developed to mitigate randomdelays in a networked wastewater control. The focus here is the process ofDissolved Oxygen (DO) concentration as part of the Activated Sludge Process (ASP). The networked wastewater control is a new method of wastewater controlin which the controller and the wastewater treatment plant are separated by a widegeographical distance and so a communication medium is required between them. The effects of network induced time delays on the DO process are investigated. Thesimulation results reveal that communication drawbacks adversely affect thestability of the closed loop DO process resulting in water odour, flocformation, poor sludge formation and eventual low effluent quality. This isbecause low DO concentration due to communication drawbacks leads to depletionof oxygen available to microorganisms that are meant to clean up thewastewater. A Smith predictor is therefore proposed to compensate for thesecommunication drawbacks. The nonlinear DO model is linearised using theinput/output feedback linearization method. PI controller is designed for thelinearised DO process while a Smith predictor scheme is proposed to eliminate timedelays in the control system. Analyticaland simulation results confirm the effectiveness of the scheme over the PIcontroller to provide robustness for the control of the input-output feedbacklinearized DO process under the influence of random communication delays

Investigation of the influence of network‐induced time delays on the activated sludge process behavior in the networked wastewater distributed systems

This paper examines the effects of networked induced time delays on the dissolved oxygen (DO) concentration in the activated sludge process (ASP) of a networked wastewater treatment plant (WWTP). This is a situation in which the controller and the wastewater plant are separated by wide geographical distance. This is a new type of WWTP control that allows two or more WWTPs to be controlled by a single controller placed in a remote location. The objective is to achieve flexibility of control and to reduce its cost. The communication medium between the controller and the WWTPs introduces communication drawbacks into the control system. The influences of network‐induced time delays [controller to actuator delay (τca) and the sensor to controller delay (τsc)] over the behavior of the DO process controlled by both nonlinear linearizing and proportional‐integral controllers are investigated for constant and random delays. Investigation of the DO process under random delays was also performed with varying linear controller parameters [proportional gain (Kp) and integral time (TI)]. Simulation results reveal that large network‐induced time delays in the closed‐loop DO process leads to depletion of the amount of oxygen available for microorganism metabolism, leading to inefficiency of the ASP. The critical delay during which the DO process becomes unstable due to communication drawbacks was also determined for constant and random delays. These values are found to vary depending on the delay type (constant/random), delay magnitude, and the linear controller parameters Kp and TI. The results of this study would provide useful information for process performance and form the basis for the design of a robust networked control for the DO process capable of mitigating communication drawbacks in a networked wastewater distributed systems. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc

The Behaviour of Vertical Bell Laboratories Layered Space-Time Algorithm Combined with Multiuser Detection Schemes in Wireless Communication System

This paper provides the performance analysis of multiuser Vertical Bell Laboratories Layered Space-Time (V-BLAST) system receiver structures for Multiple-input Multiple-Output (MIMO) channel at a base station with assumption of perfect channel estimation and perfect timing delay estimation. In MIMO channels the receivers such as decorrelator, Minimum Mean Square Error (MMSE) and Multistage Parallel Interference Cancellation (MPIC) receiver outperform the conventional receiver. Withal, since the multiple antenna interference led to a strong impact on the performance degradation of a multistage interference cancellation receiver, the performance of MPIC receiver was highly degraded based on system loading

Development of a realtime microcomputer-based logging system for diagnosis and research

In this research, a realtime temperature logging system that logs human temperature into the computer over a period was developed and the temperature chart produced is useful for diagnosis and research purposes. The graphical representation within the threshold temperature (36°C) depicts normal body temperature of a healthy person. An upshot beyond this temperature makes the logger to signal an audible alarm for medical attention. It consists of hardware and software units. The hardware consists of sensor NTC (negative coefficient of temperature) thermistor, pre-amp; analog to digital converter, buffer between analog to digital converter and computer interface port. The software was developed in Visual Basic 6.0 for interfacing through the parallel port of the computer and the program designed to provide a user-friendly environment where the measurement can be read. There is high correlation between the approach developed by this study and other standard measuring equipments — correlation of 0.994574 with standard thermistor, and correlation of 0.997785 with standard thermocouple. The temperature logged to the PC can also be viewed from another PC remotely located over a network thus providing a good framework for telemedicine