In this work we aim at developing a comprehensive rigorous mathematical model to study the interactions between the microbial metabolisms involved in the nitrogen cycle and the impact of high temperature and salinity on their performance. The model will include a detailed chemical speciation, function of pH, together with full thermodynamic data and bioenergetic calculations for the nitrogen related metabolisms as well as those potentially interacting with them. Microbial activities such as sulphate or iron reduction oxidation will be incorporated together with the more recently discovered anaerobic ammonium oxidation bacteria (anammox). The modelling work proposed will be combined with privileged access to detailed operation data at two large scale WWT plants in Abu Dhabi. We aim at both developing high impact novel knowledge on the biological nitrogen removal process at high temperatures while also potentially enhancing the WWTP operation in terms of energy footprint, operational costs and effluent quality
The main purpose of this study is to conduct numerical predictions using a commercial CFD code for atmospheric dispersion of radioactive material under UAE environmental conditions. Validation of Reynolds-Averaged Navier-Stokes (RANS) approach with the k-? turbulence model has been performed by comparing the numerical predictions with experimental data of Fackerll and Robins for both; velocity profiles, and for the passive scalar concentration and dispersion. In the three-dimension hypothetical accidental scenario case under UAE environmental characteristics, the pollutant transport, dispersion, and deposition in the area surrounding the power plant was found to be highly asymmetric and largely affected by the presence of different buildings.
A feedback loop is a common and powerful tool for designing a control system to choose optimum value of control variable. A proportional controller is simple form of controller and PID is advanced version and is widely used in feedback control of many processes. Traditionally, in many control system, analog controllers are used and digital controllers are only implemented by programming the analog controller algorithm on microprocessor in discrete time domain by quantizing bits in a limited number of levels. It has limitations as complexity in interfacing with digital world, large chip area and high power consumption. To exploit the use of on chip ALU, multiplexer and registers, digital PID controller is implemented. It has many superior qualities over analog version as high speed, improved sensitivity, better reliability and less effect due to noise and disturbance.
As penetration of wind generation increases, frequency support from wind energy conversion schemes (WECS) is becoming a necessity in order to maintain frequency levels within the acceptable limits. As far as doubly-fed induction generators (DFIGs) are concerned, operation under maximum power-point tracking algorithms does not allow for active power regulation during frequency disturbances. Furthermore, the back-to-back converters connected to the rotor circuit decouple the system frequency from the rotor speed render the machine unable to provide any inertial response. In order to address this issue, various methods providing frequency response, based on maintaining an active power reserve, are presented in literature. In this project, a control strategy that provides frequency support utilizing the ability of the DFIG to regulate both active and reactive power is proposed. The effectiveness of the method becomes substantial in networks with low X/R ratios.
Steady state analysis for protection coordination studies are widely presented in the literature. However, the influence of the performance of protection devices on stability of synchronous generators has to be verified. This paper tends to verify the existing approaches to the protection coordination problem and incorporate the limits given by the stability of generating units. The analysis are performed for modified IEEE 14-bus system supplied by three synchronous generators.
Voltage Source Converter (VSC) plays a major role in the AC/DC interconnection. Hence, its control stands as a significant issue as it determines the stability of the system. Therefore, utilization of a control algorithm that can robustly reject disturbances is highly appreciated. In this paper, a decoupled dq-vector control approach is used as a control structure due to its validity and feasibility, which has been shown in the literature. Furthermore, the tuning of the PI controllers is achieved using a new optimization algorithm. The VSC station connected to ac system is subject, mainly, to two types of disturbances: source and load disturbance. At first, the system is optimized for each individually based on the integral time absolute error (ITAE) criterion. Then, both disturbances are weightily summed in order to provide the optimum disturbance rejection. Simulation results demonstrate the validity and robustness of such an approach.
The use of Sliding Mode Controllers (SMC) has of been considered a good solution for the successful control of system with major uncertainties and disturbances. These controllers maintain healthy system behavior even in the presence of un-modelled dynamics. However, the chattering problem which results from the use of these controllers remains a huge downfall of SMCs. Ideally, SMCs must undergo switching with infinite frequency during the sliding phase but this inhibit by the existence of parasitic dynamics which effectively increase the input relative degree of the system. Accordingly, the responsiveness and performance of SMCs is much dictated by the switching frequency outcome. Frequently, to control the speed of induction motor, SMC is implemented in the external speed loop which restricts the switching frequency of the robust controller. We consider the application of SMC in the inner loop as an alternative which in theory should lead to ideal sliding.
Hybrid kinematics mechanisms combine the advantages of purely serial and purely parallel kinematics mechanisms. This paper proposes a novel hybrid planar 3PRR mechanism which can be utilized for machine tool. As the main drawback of parallel mechanism is small workspace, the workspace of the proposed mechanism has been optimized by using constrained nonlinear optimization. It is shown that the optimization gives significant improvement of the workspace area and shape.
Task partitioning in multi-robot systems involves breaking down tasks or partitioning them into smaller tasks tackled by different robots in the system. Some of the benefits of this approach is less interference between the individual agents as they are more segregated, an improved scalability, and an improved transport efficiency. This approach allows for a better overall group performance, leads to specialization and aids in parallel task execution. In this paper, a new problem tackling self-organized task allocation method in the context of swarm robotics is investigated by using task partitioning. The method does not use any sort of global communication; instead, indirect communication is achieved through the concept of stigmergy.
In this paper, the algorithm of the Parametric Risk Field (PRF) concept is applied for haptic teleoperation of Unmanned Ground Vehicle (UGV). PRF is a type of the Artificial Force Fields (AFF) which maps 2D environmental constraint into repulsive forces. AFF is applied in haptic feedback to allow operators to interpret the repulsive forces as impedance to their control deflections when a potential for collision exists. PRF consists of many user-defined parameters, some are independent, and others are dependent on the UGV's velocity and obstacle displacement. The algorithm was tested on a UGV Teleoperated by robotic arm. The results has shown alignment between PRF values and experimental mapped force. The future plans for this work is to develop the PRF to map 3D environmental constraint in order to be applied on Unmanned Aerial Vehicles (UAV's)
