Application of Genetic Algorithm for the Assessment of Spontaneous Heating Susceptibility of Coal

When coal is exposed to air, oxygen is absorbed and some portions of the coal substance with production of some gases (mainly CO, CO2), water vapour with the evolution of some amount of heat. This oxidation takes place even at ambient temperatures and humidity. It is a slow process and the heat evolved is carried away by air. This process of self heating of coal or other carbonaceous material resulting eventually in its ignition is termed as “spontaneous heating” or “auto oxidation”. Mine fire is major hazard in coal mining industry worldwide. The first step to take proper preventive measure is the assessment of liability of coal seams towards self heating. Various expert systems are being adopted these days to predict the self heating properties of coal. In the present work a new soft computing approach, viz. genetic algorithm has been applied for categorization of coal samples, depending upon their spontaneous heating susceptibility. EXPERIMENTAL INVESTIGATION Eleven samples were collected from South Eastern Coalfield Limited, six samples from Mahanadi Coalfield Limited, three samples from Eastern coal field Limited, three samples from BCCL, two samples from Central Coal field Limited and one each from Western coal field Limited and NCL. The samples were collected following channel sampling procedure. Some of the samples were well known for their high and low susceptibility in Indian coalfields. The proximate constituents were determined in laboratory using the standard experimental procedure. The crossing point temperature of these coal samples was determined at a heating rate of 10C/ minute with an air flow rate of 80 cc/min. The onset temperature from DTA thermograms of these coal samples was determined by intersection between two tangents drawn at the inflexion point of the endothermic region and another tangent was drawn at rising portion of curve of stage III. The wet oxidation potential of the coal samples were determined using KMnO4 solution. Table 1 Proximate constituents, CPT, onset temperatures and wet oxidation potential difference of coal samples Sample no. Moisture (%) VM (%) Ash (%) CPT (0C) Tc (0C) WOPD (mV) 1 4.974 31.949 23.913 159 171.07 112 2 9.955 30.395 12.6 171 129.49 112 3 5.785 27.35 18.6 163 123.4 114 4 5.894 30.706 26.25 167 143.41 119 5 7.669 30.921 10.8 162 138.36 101 6 9.164 26.586 16.241 185 123.12 113 7 6.488 28.262 10.395 165 162.56 109 8 3.96 26.134 23.3 173 163.63 80 9 2.932 30.883 12.037 163 186.8 99.9 10 1.948 33.052 17.527 156 184.15 108 11 2.345 29.641 15.725 165 189.56 103 12 4.48 25.01 44.02 169 155.93 102 13 2.4 23.27 52.3 174 147.29 104 14 14.5 31.97 12.35 155 158.46 51.2 15 8.97 29.49 22.88 147 153.34 47.5 16 9.59 28.93 7.68 149 124.82 54.1 17 11.13 25.19 38.46 149 171.87 99.3 18 1 17.36 15.73 180 188.98 26.6 19 1.9 33.08 16 155 128.38 63.9 20 0.6 22.32 10.73 160 169.66 41.8 21 8.43 24.43 9.6 152 162.3 87.8 22 1.8 36.13 14.27 150 129.33 106.6 23 10 32.27 18 144 132.94 143.1 24 10.52 29.47 11.91 152.5 136.87 121.8 25 7.67 29.83 18.88 155 145.33 123.8 26 14.39 29.31 12.76 150 128 161 27 9.68 29.8 18.12 138 122.67 206 APPLICATION OF GENETIC ALGORITHM A genetic algorithm (GA) inspired by Darwin's theory of evolution is a search technique used in computing to find exact or approximate solutions to optimization and search problems. Genetic algorithms are a particular class of evolutionary algorithms (EA) that use techniques inspired by evolutionary biology such as inheritance, mutation, selection, and crossover. Genetic algorithms are. In the present work coal seams are classified by using genetic algorithm to determine their spontaneous heating susceptibility, taking Euclidean distance as fitness function. For this purpose a program was written in C++. The program was run using four variables: 1. Moisture 2. Volatile matter 3. Ash 4. One of the following susceptibility indices at a time. • Crossing point temperatures • Onset temperatures • Wet oxidation potential values It was observed that the results were consistent, when four clusters were obtained, so four clusters were obtained in all cases. DISCUSSION AND CONCLUSION The genetic algorithm takes into account the intrinsic parameters determined by proximate analysis, which is regular affair in the field as it is required to determine the grade of coals. It was observed that the categorization matched with the field results fairly accurately. It is hoped that the output of the work will benefit the practicing mining engineers and researchers to a greater extent in categorizing coal samples, depending upon their spontaneous heating susceptibility and accordingly they can plan the mining activities and adopt advance precautionary measures to deal with fire problems in mines. REFERENCES • Ramlu, M.A.; 1991, ” Mine Disasters and Mine Rescue”, Chapter-1, Mine fires, Oxford and IBH publishing Co.Pvt.Ltd, p: 10-20 • Banerjee, S.C.; 1998,” Prevention and Combating Mine fires”, Allied publisher, p: 30-66 • Goldberg D.E.,1999,”Genetic Algorithms”,Chapter-1, A gentle introduction to genetic algorithms, Addision wesley longman publication, 1st edition, page:1-2

A Novel Power-Efficient Wireless Multi-channel Recording System for the Telemonitoring of Electroencephalography (EEG)

This research introduces the development of a novel EEG recording system that is modular, batteryless, and wireless (untethered) with the supporting theoretical foundation in wireless communications and related design elements and circuitry. Its modular construct overcomes the EEG scaling problem and makes it easier for reconfiguring the hardware design in terms of the number and placement of electrodes and type of standard EEG system contemplated for use. In this development, portability, lightweight, and applicability to other clinical applications that rely on EEG data are sought. Due to printer tolerance, the 3D printed cap consists of 61 electrode placements. This recording capacity can however extend from 21 (as in the international 10-20 systems) up to 61 EEG channels at sample rates ranging from 250 to 1000 Hz and the transfer of the raw EEG signal using a standard allocated frequency as a data carrier. The main objectives of this dissertation are to (1) eliminate the need for heavy mounted batteries, (2) overcome the requirement for bulky power systems, and (3) avoid the use of data cables to untether the EEG system from the subject for a more practical and less restrictive setting. Unpredictability and temporal variations of the EEG input make developing a battery-free and cable-free EEG reading device challenging. Professional high-quality and high-resolution analog front ends are required to capture non-stationary EEG signals at microvolt levels. The primary components of the proposed setup are the wireless power transmission unit, which consists of a power amplifier, highly efficient resonant-inductive link, rectification, regulation, and power management units, as well as the analog front end, which consists of an analog to digital converter, pre-amplification unit, filtering unit, host microprocessor, and the wireless communication unit. These must all be compatible with the rest of the system and must use the least amount of power possible while minimizing the presence of noise and the attenuation of the recorded signal A highly efficient resonant-inductive coupling link is developed to decrease power transmission dissipation. Magnetized materials were utilized to steer electromagnetic flux and decrease route and medium loss while transmitting the required energy with low dissipation. Signal pre-amplification is handled by the front-end active electrodes. Standard bio-amplifier design approaches are combined to accomplish this purpose, and a thorough investigation of the optimum ADC, microcontroller, and transceiver units has been carried out. We can minimize overall system weight and power consumption by employing battery-less and cable-free EEG readout system designs, consequently giving patients more comfort and freedom of movement. Similarly, the solutions are designed to match the performance of medical-grade equipment. The captured electrical impulses using the proposed setup can be stored for various uses, including classification, prediction, 3D source localization, and for monitoring and diagnosing different brain disorders. All the proposed designs and supporting mathematical derivations were validated through empirical and software-simulated experiments. Many of the proposed designs, including the 3D head cap, the wireless power transmission unit, and the pre-amplification unit, are already fabricated, and the schematic circuits and simulation results were based on Spice, Altium, and high-frequency structure simulator (HFSS) software. The fully integrated head cap to be fabricated would require embedding the active electrodes into the 3D headset and applying current technological advances to miniaturize some of the design elements developed in this dissertation

Improving dimensional accuracy of fused deposition modelling (FDM) parts using response surface methodology

Fused deposition modelling is one of rapid prototyping process that uses plastic materials such as ABS (acrylonitrile-butadiene-styrene) in the semi molten state to produce prototypes. FDM is an additive process and the prototypes are made by layer by layer addition of the semi-molten plastic material onto a platform from bottom to top. Primary process parameters such as layer thickness, raster angle and part orientation in addition to their interactions are studied in the present dissertation that influences the dimensional accuracy of the part produced by the process of Fused Deposition Modelling (FDM). Due to shrinkage of the filaments, the dimensions of the CAD model does not match with the FDM processed part. The shrinkage dominates along length and width of the build part but a positive deviation is observed along thickness direction. Influence of each parameter on responses such as percentage change in length, width, and thickness of the build part are essentially studied. The effect of process parameters on responses are studied via Response surface methodology (RSM). RSM is used to calculate the regression coefficients and the function is made with the significant factors. Then optimization of process parameters is made by genetic algorithm so as to minimize the percentage change in length, width and thickness

Reconfigurable Varactor-Based Microwave Components for Low-Cost Antenna Array Design: Phase Shifters, Attenuators and Diplexers

Phased array antennas are important for advanced wireless communications, providing high directivity and beam steering capabilities. However, conventional phased arrays are expensive, bulky, heavy and power-hungry due to their complex architecture and electronic controls. For systems demanding low cost, light weight, compact size, and low power consumption, reconfigurable antenna arrays can be a practical alternative to traditional phased arrays. Electronically controlled reconfigurable antennas offer the ability to adjust their operating frequency, radiation pattern, polarization, or any combinations of these aspects by using tunable electronic components such as PIN diodes, switches, varactors and/or microelectromechanical systems (MEMS). One way to realize reconfigurable antenna array is to start by designing a reconfigurable feeding network and then co-designing corresponding antenna elements, before combining these two structures to form the whole array based on the system requirements. However, when designing low-cost and compact reconfigurable antenna arrays, several critical aspects should be taken into consideration. Firstly, the reconfigurable feeding network may result in a large number of components and a complex structure, leading to a higher insertion loss and a possible degradation in antenna performance through reduced efficiency. Secondly, if the feeding network is not designed properly, integrating it into the system can lead to a high demand in space, consequently enlarging the overall size, manufacture complexity and cost. In this context, compact, seamlessly-integrable, low-power, low-cost and tunable microwave components are needed to build reconfigurable feeding networks. Through using these feeding networks, low-cost and compact reconfigurable antenna arrays can be realized as alternatives to conventional phased arrays. Varactor-based phase shifters to control the signal phase, reconfigurable attenuators to control the signal magnitude and reconfigurable diplexers to control the signal frequency are essential components to construct these so-called reconfigurable feeding networks. This is in line with the goal of this thesis, which comprises three coherent objectives. Firstly, the dissertation presents a concept of low-cost varactor-based phase shifters, which are operating in differential mode. A phase shifter pair based on this concept is able to supply full- 360◦ phase difference tuning range between its two output ports. The devices can be directly integrated with 50 Ω feed transmission lines, which results in a compact, lowcost and lightweight design of the feeding network and saves space which would be required by conventional phase shifter blocks. Based on such differential phase shifter pairs, a 1×4 linear dielectric resonator antenna array is designed, which is excited by a feeding network comprising 3 phase shifter pairs to control the array scanning sumpattern continuously from -45◦ to 45◦ and the null of a difference pattern from -30◦ to 30◦. A dedicated procedure for accurately calibrating these beam-steerable antennas is also proposed, aiming to provide a general approach to enhance the performance of the reconfigurable feeding network. Secondly, a tunable transmission-type attenuator with easily-extendable and tunable attenuation level, small initial insertion loss, and satisfactorily low reflection coefficient is presented, which is integrated onto a 50 Ω microstrip transmission lines with several side-loaded shorted-end varactorbased stubs. This arrangement allows a compact and low-loss structure, as well as seamless integration with planar transmission lines in microwave circuits, which also makes them suitable for applications with limited real estate. It is proven that a 3-stub attenuator can offer tunable attenuation from 1.0 to 13.5 dB with reflection coefficient lower than -11.4 dB, and that by cascading them a larger attenuation range can be obtained. Thirdly, a frequency-switchable varactor-based diplexer concept is proposed for a low-cost and compact pattern- and frequency-switchable microstrip antenna array. This diplexer concept, which represents an extension in functionality of the differential phase shifter pair, is able to supply different responses to different frequencies in a wide-band range, instead of utilizing the phase difference performance in a narrow operation band. Seamless integration with the feeding network enables a dual-band antenna pair to become a pattern- and frequency-switchable array with unique functionality. All the results presented in this thesis are derived fromvaractor-based microwave components that offer a range of benefits, including low cost, lightweight construction, low power consumption, and a seamless integration topology. All these proposed reconfigurable devices allow construction of reconfigurable feeding networks with phase and magnitude tuning abilities, as well as frequency reconfigurability. This means that antenna arrays fed by this type of feeding networks can achieve versatile and competitive reconfigurability in their radiation performance, while maintaining a compact size, low weight, low power consumption and affordability.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Mechanical Engineering, 202

Modeling EMI Resulting from a Signal Via Transition Through Power/Ground Layers

Signal transitioning through layers on vias are very common in multi-layer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current must switch from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in noise on the power bus that can lead to signal integrity, as well as EMI problems. Numerical methods, such as the finite-difference time-domain (FDTD), Moment of Methods (MoM), and partial element equivalent circuit (PEEC) method, were employed herein to study this problem. The modeled results are supported by measurements. In addition, a common EMI mitigation approach of adding a decoupling capacitor was investigated with the FDTD method

Metamaterial

In-depth analysis of the theory, properties and description of the most potential technological applications of metamaterials for the realization of novel devices such as subwavelength lenses, invisibility cloaks, dipole and reflector antennas, high frequency telecommunications, new designs of bandpass filters, absorbers and concentrators of EM waves etc. In order to create a new devices it is necessary to know the main electrodynamical characteristics of metamaterial structures on the basis of which the device is supposed to be created. The electromagnetic wave scattering surfaces built with metamaterials are primarily based on the ability of metamaterials to control the surrounded electromagnetic fields by varying their permeability and permittivity characteristics. The book covers some solutions for microwave wavelength scales as well as exploitation of nanoscale EM wavelength such as visible specter using recent advances of nanotechnology, for instance in the field of nanowires, nanopolymers, carbon nanotubes and graphene. Metamaterial is suitable for scholars from extremely large scientific domain and therefore given to engineers, scientists, graduates and other interested professionals from photonics to nanoscience and from material science to antenna engineering as a comprehensive reference on this artificial materials of tomorrow

Reconfigurable Metasurfaces for Beam Scanning Planar Antennas

We are studying the implementation of 'Scanning Antenna dedicated to the applications of satellite communications geostationary. The structures developed are suitable for to be on board an airplane or a train. The architecture of the antenna developed consists of a double linear network in two transverse dimmensions. The scan in each network is provided by the lines coplanar to metamaterials controlled by varactor. We porposons of new methods characterization of discontinuities coplanar online for the line design. In addition, a energy harvesting system has be designed to feed radiating elements and tested with patch different antennas. Finally, we are considering co-integration radiating structures and CRLH lines as well as control electronic by the diodes

Artificial Magnetic Materials: Limitations, Synthesis and Possibilities

Artificial magnetic materials (AMMs) are a type of metamaterials which are engineered to exhibit desirable magnetic properties not found in nature. AMMs are realized by embedding electrically small metallic resonators aligned in parallel planes in a host dielectric medium. In the presence of a magnetic field, an electric current is induced on the inclusions leading to the emergence of an enhanced magnetic response inside the medium at the resonance frequency of the inclusions. AMMs with negative permeability are used to develop single negative, or double negative metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave or optical frequencies where the natural magnetic materials fail to work efficiently. Artificial magnetic materials have proliferating applications in microwave and optical frequency region. Such applications include inversely refracting the light beam, invisibility cloaking, ultra miniaturizing and frequency bandwidth enhancing low profile antennas, planar superlensing, super-sensitive sensing, decoupling proximal high profile antennas, and enhancing solar cells efficiency, among others. AMMs have unique enabling features that allow for these important applications. Fundamental limitations on the performance of artificial magnetic materials have been derived. The first limitation which depends on the generic model of permeability functions expresses that the frequency dispersion in an AMM is limited by the desired operational bandwidth. The other constraints are derived based on the geometrical limitations of inclusions. These limitations are calculated based on a circuit model. Therefore, a formulation for permeability and magnetic susceptibility of the media based on a circuit model is developed. The formulation is in terms of a geometrical parameter that represents the geometrical characteristics of the inclusions such as area, perimeter and curvature, and a physical parameter that represents the physical, structural and fabrication characteristics of the medium. The effect of the newly introduced parameters on the effective permeability of the medium and the magnetic loss tangent are studied. In addition, the constraints and relations are used to methodically design artificial magnetic material meeting specific operational requirements. A novel design methodology based on an introduced analytical formulation for artificial magnetic material with desired properties is implemented. The synthesis methodology is performed in an iterative four-step algorithm. In the first step, the feasibility of the design is tested to meet the fundamental constraints. In consecutive steps, the geometrical and physical factors which are attributed to the area and perimeter of the inclusion are synthesized and calculated. An updated range of the inclusion's area and perimeter is obtained through consecutive iterations. Finally, the outcome of the iterative procedure is checked for geometrical realizability. The strategy behind the design methodology is generic and can be applied to any adopted circuit based model for AMMs. Several generic geometries are introduced to realize any combination of geometrically realizable area and perimeter (s,l) pairs. A realizable geometry is referred to a contour that satisfies Dido's inequality. The generic geometries introduced here can be used to fabricate feasible AMMs. The novel generic geometries not only can be used to enhance magnetic properties, but also they can be configured to provide specific permeability with desired dispersion function over a certain frequency bandwidth with a maximum magnetic loss tangent. The proposed generic geometries are parametric contours with uncorrelated perimeter and area function. Geometries are configured by tuning parameters in order to possess specified perimeter and surface area. The produced contour is considered as the inclusion's shape. The inclusions are accordingly termed Rose curve resonators (RCRs), Corrugated rectangular resonators (CRRs) and Sine oval resonators (SORs). Moreover, the detailed characteristics of the RCR are studied. The RCRs are used as complementary resonators in design of the ground plane in a microstrip stop-band filter, and as the substrate in design of a miniaturized patch antenna. The performance of new designs is compared with the counterpart devices, and the advantages are discussed