A novel adaptive deadbeat- based control for load frequency control of low inertia system in interconnected zones north and south of Scotland

An adaptive deadbeat (ADB) controller was developed to investigate its capability in providing a fast frequency response to an electrical power system. This controller was developed to meet the requirements of the National Grid System Operability Framework (SOF), which requires frequency to be accelerated in line with a fast rate of change of frequency (RoCoF) when a high rate of nonsynchronous machines are presented. The controller’s parameters were optimized using particle swarm optimization (PSO) to ensure a robust operation and to maintain the proper operation of the power system. The design of the ADB controller was then integrated with the multiarea model of the north and south zones of Scotland. This model was developed in order to conform to the future energy requirements scenario stated by National Grid whereby regional control can be provided in both the north and south of Scotland. In comparison with the standard PI and Fuzzy-PI controllers used in the four highlighted case studies, it was shown that the ADB controller was able to significantly reduce the RoCoF and deviation of frequency when a sudden loss of generation occurred in a low inertia zone. The ADB also showed high robustness against a wide range of operating conditions.     

Nonlinear adaptive noise-induced algorithm and its application in penetration signal

A nonlinear adaptive noise induced algorithm with nonlinear weights was proposed to extract rigid body deceleration during penetration events; it has 3rd-order nonlinear weight, which ensures deceleration curve is smooth everywhere (not only continuous) and avoids sharp points (crucial for targets detection). In addition, an autocorrelation algorithm was improved by applying moving window method to be compared with the proposed nonlinear adaptive algorithm. By calculating penetration depth and Power Spectrum Density (PSD) of 4 deceleration time series, we show that the nonlinear adaptive algorithm more effectively reduces noise in deceleration for striking velocities between 538 and 800 m/s compared with Adaptive Paйta Criterion, moving window autocorrelation and wavelet algorithms. It is further shown that the proposed adaptive algorithm is of the same order as the other 3 methods in terms of computational complexity.     

Realization of active power filter based on indirect current control algorithm using Xilinx system generator for harmonic elimination

Realization of active power filter with Model Based Design approach is presented in this paper. The approach adopts different modeling platforms as well as selection of proper hardware for step wise verification and testing. The active power filter model is developed using the Matlab/Simulink platform for single phase. The efficiency of the control algorithms such as synchronous detection method and indirect current control for active power filter is analyzed. Efficient control algorithm is developed by Xilinx system generator which is incorporated into Simulink as Xilinx tool box. Xilinx system generator provides a virtual platform for easy and effective design of the required system models in FPGA (field programmable gate array) design environments. Optimized automatic VHDL code is generated for the control algorithm which is simulated using ISE 13.2 for the generation of switching signals for the control of IGBTs of the active power filter. Suitable compensation signal is generated from the active power filter for the better elimination harmonics to improve the power quality. THD is reduced to a considered value which is able to satisfy the limits of the IEEE standard.     

Strength,sorption and abrasion characteristics of concrete using ferrochrome ash (FCA) and lime as partial replacement of cement

This paper presents the results of experimental investigations and microstructure study carried out to evaluate the possibility of utilization of ferrochrome ash (FCA), a waste product from ferroalloys industries for partial replacement of cement in concrete preparation. FCA is used in four different substitution rates such as 10, 20, 30 and 40% along with 7% lime. Various strength and durability tests were conducted to understand the effects of FCA and lime on performance of concrete. Test results revealed that replacement of cement by FCA in various % with 7% lime enhanced the 28 days compressive strength 1.5–13.5%, flexural strength 4.5–9%, bond strength 15–29%, abrasion resistance 10–23% and reduced the sorptivity 25–43%. The concrete containing 40% FCA and 7% lime, replacing 47% of ordinary Portland cement (OPC) in total, exhibited strength of normal concrete or even more at all ages. XRD and petrography studies confirmed the results of mechanical and durability properties.     

Preparation of ytterbium substituted BiFeO3 multiferroics by mechanical activation

Samples in the system Bi_1−xYb_xFeO₃ (0.02 ≤ × ≤ 0.07) have for the first time been prepared by mechanical activation followed by sintering. XRD and DSC measurements show that the solubility limit of ytterbium in the R3c Bi_1−xYb_xFeO₃ system is reached at x∼0.03. Higher ytterbium contents lead to a two-phase mixture of a main R3c phase of approximate composition Bi_0.97Yb_0.03FeO₃ and ytterbium enriched secondary phases that cannot be readily indexed or quantified due to their small amount. DSC and temperature-dependent XRD showed that while the magnetic ordering temperature, T_N, was unaffected by Yb substitution, the ferroelectric ordering, T_C, declined. Temperature-dependent XRD patterns show that all samples exhibit rhombohedral R3c to orthorrhombic Pnma phase transitions. Diffuse reflectance spectroscopy suggests the potential use of the samples in photocatalytic applications due to their low band gap energy. Impedance spectroscopy and magnetic measurements show that samples are electrically homogenous and highly insulating, exhibiting antiferromagnetic behaviour at room temperature.     

Tensile properties of real unidirectional Kevlar/epoxy composites

Mechanical behaviour, tensile strength and failure modes in real unidirectional Kevlar/epoxy composites, loaded parallel to the fibres, at volume fraction (V_f) range 0.26–0.73, were investigated. It was found that the measured tensile strengths deviated from the expected values calculated from the Rule of Mixture. The deviation, which was minimal at V_f of about 0.5, was mainly due to geometrical deficiencies typical of real composites. At V_f<0.5 it could be explained by non-homogeneous fibre spread and distribution of fibres. At V_f>0.5 the deviation was explained by the increasing lack of matrix between some adjacent fibres and by squeezing of fibres. The initial part of loading was typified by straightening out of non-axial fibres, accompanied by fibre/matrix debonding. The straightening process was completed at a stress level of about 0.6–0.7 of the composite strength. Matrix damage began at this stress level and continued to develop up to final failure. Failure of Kevlar fibres was noted to occur only at an extremely short loading interval coinciding with the catastrophic final failure. This was due to the small scatter of Kevlar fibre strength.     

Comment on “Modelling of the APS plasma spray process using artificial neural networks: Basis,requirements and an example” by Guessasma et al. [Comput. Mater. Sci. 29 (2004) 315]

This paper comments on a series of papers using artificial neural networks published in materials journals. The issues discussed include the size of the database for training a neural network, database enlargement for training a neural network, and extrapolation based on modelling results. The paper includes criticisms of other mistakes in those previously published papers.     

Real-time multimedia processing in video sensor networks

Video sensor networks (VSNs) has become the recent research focus due to the rich information it provides to address various data-hungry applications. However, VSN implementations face stringent constraints of limited communication bandwidth, processing capability, and power supply. In-network processing has been proposed as efficient means to address these problems. The key component of in-network processing, task mapping and scheduling problem, is investigated in this paper. Although task mapping and scheduling in wired networks of processors has been extensively studied, their application to VSNs remains largely unexplored. Existing algorithms cannot be directly implemented in VSNs due to limited resource availability and shared wireless communication medium. In this work, an application-independent task mapping and scheduling solution in multi-hop VSNs is presented that provides real-time guarantees to process video feeds. The processed data is smaller in volume which further releases the burden on the end-to-end communication. Using a novel multi-hop channel model and a communication scheduling algorithm, computation tasks and associated communication events are scheduled simultaneously with a dynamic critical-path scheduling algorithm. Dynamic voltage scaling (DVS) mechanism is implemented to further optimize energy consumption. According to the simulation results, the proposed solution outperforms existing mechanisms in terms of guaranteeing application deadlines with minimum energy consumption.     

MOTION PLANNING OF AN INTELLIGENT ROBOT USING GA MOTIVATED TEMPORAL ASSOCIATIVE MEMORY

ABSTRACT

The paper discusses the concept of re-planning for a mobile robot in the presence of semidynamic obstacles. The navigational planning is done by employing genetic algorithm until it reaches the goal point. The path segments traversed by the mobile robot are stored by a simple matrix, employing temporal associative memory. During subsequent traversal, the robot utilizes the previously stored matrix to avoid an obstacle path. In case of deadlock, the robot back tracks using TAM and finds alternative paths to reach the goal. This algorithm has been realized on a Pioneer 2DX mobile robot of ActiveMedia Robotic LLC, USA, through client server architecture. The result shows that the robot reaches the goal within a vicinity of a 20 mm radius.     

Characterization of Polyacrylonitrile Nanocomposites by Reinforcement of Functionalized Single-Walled Carbon Nanotubes

Polyacrylonitrile/functionalized single-walled carbon nanotubes (PAN/f-SWCNTs) nanocomposites were synthesized by an emulsifier-free in situ polymerization process. Interaction of polyacrylonitrile with functionalized single-walled carbon nanotubes was evidenced by ultraviolet-visible and Fourier transforms infrared spectroscopy. The structure and morphology of nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy. Electrical conductivity was found to be increased by addition of f-SWCNTs. Thermogravimetric analysis study of PAN/f-SWCNT nanocomposites show more thermal resistance compared to the virgin PAN. The oxygen barrier property of PAN/f-SWCNT nanocomposites was reduced by eight times with increasing f-SWCNTs proportions.