Homogenization studies for optical sensors based on sculptured thin films

In this thesis we investigate theoretically various types of sculptured thin film (STF) envi�sioned as platforms for optical sensing. A STF consists of an array of parallel nanowires which can be grown on a substrate using vapour deposition techniques. Typically, each nanowire has a diameter in the range from ∼ 10−300 nm while the film thickness is . 1µm. Through careful control of the fabrication process, both the optical properties and the porosity of the STF can be tailored to order. These abilities make STFs promising for optical sensing applications, wherein it is envisaged that the material to be sensed infiltrates the void re�gion in between the parallel nanowires and hence changes the optical properties of the STF. Various homogenization formalisms can be used to estimate the constitutive parameters of the infiltrated STFs. In this thesis two different homogenization formalisms were used: the Bruggeman formalism (extended and non–extended versions) and the strong-permittivity�fluctuation theory (SPFT). These were used in investigations of the following optical–sensing scenarios: (i) Electromagnetic radiation emitted by a dipole source inside an infiltrated chiral STF. The effects of using the extended Bruggeman homogenization formalism, which takes into account the nonzero size of the component particles, were studied. (ii) Surface–plasmon– polariton waves on a metal–coated, infiltrated columnar thin film. The influences of using the extended SPFT formalism, which takes into account the nonzero size of the component particles and their statistical distributions, were explored. (iii) A metal-coated infiltrated chiral STF which supports both surface-plasmon-polariton waves and the circular Bragg phe�nomenon. The possibility of using in parallel both surface-plasmon-polariton waves and the circular Bragg phenomenon was investigated using the non–extended Bruggeman formalism. Our numerical studies revealed that the design performance parameters of the infiltrated STF are bode well for these optical–sensing scenarios. The use of inverse Bruggeman formalism was also investigated: this was found to be problematic in certain constitutive parameter regimes, but not those for optical–sensing scenarios considered in this thesis

Generalized fuzzy topographic topological mapping

Fuzzy Topographic Topological Mapping (FTTM) is a model for solving neuromagnetic inverse problem. FTTM consists of four topological spaces which are connected by three homeomorphisms. FTTM 1 and FTTM 2 were designed to present 3-D view of an unbounded single current and bounded multicurrent sources, respectively. It has been showed that FTTM 1 and FTTM 2 are homeomorphic and this homeomorphism will generate another 14 FTTM. There is a conjecture stated that if there exist n numbers of FTTM, then they will generate another n4 ? n new FTTM. In this thesis, the conjecture is proven by using geometrical features of FTTM. In the process, several definitions such as sequence of FTTM, sequence of polygon, sequence of cube with combination of two, three and four FTTM are developed. Some geometrical and algebraic properties of sequences of FTTM are identified and proven. A new conjecture is also proposed in this thesis which states that the number of generating Fkn if there are k components and n models of Fk is nk ? n . Surprisingly, the nonzero sequence of cube with combination of two, three and four FTTM appeared in Pascal’s Triangle

Background subtraction challenges in motion detection using Gaussian mixture model: a survey

Motion detection is becoming prominent for computer vision applications. The background subtraction method that uses the Gaussian mixture model (GMM) is utilized frequently in camera or video settings. However, there is still more work that needs to be done to develop a reliable, accurate and high-performing technique due to various challenges. The degree of difficulty for this challenge is primarily determined by how the object to be detected is defined. It could be influenced by the changes in the object posture or deformations. In this context, we describe and bring together the most significant challenges faced by the background subtraction techniques based on GMM for dealing with a crucial background situation. Therefore, the findings of this study can be used to identify the most appropriate GMM version based on the crucial background situation

On chemiluminescent emission from an infiltrated chiral sculptured thin film

The theory describing the far-field emission from a dipole source embedded inside a chiral sculptured thin film (CSTF), based on a spectral Green function formalism, was further developed to allow for infiltration of the void regions of the CSTF by a fluid. In doing so, the extended Bruggeman homogenization formalism--which accommodates constituent particles that are small compared to wavelength but not vanishingly small--was used to estimate the relative permittivity parameters of the infiltrated CSTF. For a numerical example, we found that left circularly polarized (LCP) light was preferentially emitted through one face of the CSTF while right circularly polarized (RCP) light was preferentially emitted through the opposite face, at wavelengths within the Bragg regime. The centre wavelength for the preferential emission of LCP/RCP light was red shifted as the refractive index of the infiltrating fluid increased from unity, and this red shift was accentuated when the size of the constituent particles in our homogenization model was increased. Also, the bandwidth of the preferential LCP/RCP emission regime decreased as the refractive index of the infiltrating fluid increased from unity

On columnar thin films as platforms for surface-plasmonic-polaritonic optical sensing: higher-order considerations

The ability to tailor the porosity and optical properties of columnar thin films (CTFs) renders them promising platforms for optical sensing. In particular, surface-plasmon-polariton (SPP) waves, guided by the planar interface of an infiltrated CTF and a thin layer of metal, may be harnessed to detect substances that penetrate the void regions in between the columns of a CTF. This scenario was investigated theoretically using a higher-order homogenization technique, based on an extended version of the second-order strong-permittivity-fluctuation theory, which takes into account the size of the component particles which make up the infiltrated CTF and the statistical distribution of these particles. Our numerical studies revealed that as the size of the component particles increases and as the correlation length that characterizes their distribution increases: (i) the phase speed of the SPP wave decreases and the SPP wave's attenuation increases; (ii) the SPP wave's penetration into the CTF decreases; (iii) the angle of incidence required to excite the SPP wave in a modified Kretschmann configuration increases; (iv) the sharpness of the SPP trough in the graph of reflectance versus angle of incidence increases; and (v) the sensitivity to changes in refractive index of the infiltrating fluid decreases

The extended monod model for microalgae growth and nutrient uptake in different wastewaters

Water pollution is a serious issue which always being concerned by public. Microalgae for wastewater treatment is an effective way to solve the problem due to its eco-friendly and apparently low cost. This research aims to investigate the efficiency of the mathematical model to estimate the microalgae growth and nutrient uptake by microalgae in wastewaters. The extended Monod model is applied in the Verhulst model to describe the microalgae growth and nutrient uptake by microalgae whereas microalgae Botryococcus sp. is the species of microalgae used in this research. The microalgae Botryococcus sp. growth and nutrient uptake in domestic, agricultural and industrial wastewater are estimated and the results reveal that the extended Monod model is suitable for the estimation of microalgae growth and nutrient uptake by microalgae. In addition, microalgae Botryococcus sp. is promising for treating domestic, agricultural and industrial wastewater

Comparative analysis for performance measurements of software testing between mobile applications and web applications

Software testing has an important role in software engineering, and is fundamental to Software Quality Assurance (SQA). Besides the popularity of web applications, mobile applications have gained paralleled advancement despite increasing complexity. On one hand, this issue reflects the rising concerns for ensuring performance both of web and mobile applications. On the other hand, a comparative analysis of software testing issues between web and mobile applications has not been completed. Thus, this study aims to employ an effective testing approach that is able to adapt both of web and mobile application testing to detect possible failures. To achieve this, UML activity diagrams were developed from four case studies for web and mobile applications to describe the behaviour of those applications. Test cases were then generated by using the MBT technique from the developed UML activity diagrams. Performance measurements Hits per Second, Throughput and Memory Utilization for each case study were evaluated by execution of test cases that were generated by using HP LoadRunner 12.02 tool. Finally, the MSE of performance measurements was compared and analysed among the four case studies. The experimental results showed that the disparity between the mobile applications and web applications was obvious. Based on the comparison analysis for software testing of mobile applications versus web applications that was the web applications were lesser than mobile applications for software testing of four case studies in terms each of the Hits per Second, Throughput and Memory Utilization. Consequently, mobile applications need more attention in the testing process

Towards an experimental realization of affinely transformed linearized QED vacuum via inverse homogenization

Within the framework of quantum electrodynamics (QED), vacuum is a nonlinear medium which can be linearized for a rapidly time-varying electromagnetic field with a small amplitude subjected to a magnetostatic field. The linearized QED vacuum is a uniaxial dielectric-magnetic medium for which the degree of anisotropy is exceedingly small. By implementing an affine transformation of the spatial coordinates, the degree of anisotropy may become sufficiently large as to be readily perceivable. The inverse Bruggeman formalism can be implemented to specify a homogenized composite material (HCM) which is electromagnetically equivalent to the affinely transformed QED vacuum. This HCM can arise from remarkably simple component materials; for example, two isotropic dielectric materials and two isotropic magnetic materials, randomly distributed as oriented spheroidal particles

A verhulst model for microalgae growth and nutrient removal in domestic wastewater

This research aims to investigate the ability of theVerhulst model to estimate the growth of microalgae and the nutrient removal by microalgae in wastewater. First, the Verhulst model is applied to reproduce the previous results of the microalgae Chlorella Vulgaris growth and nutrient removal in different wastewaters. In this research, the result showed a similar agreement. Next, the Verhulst model is implemented to predict the growth of microalgae Botryococcus sp. and nutrient removal by microalgae Botryococcus sp. in domestic wastewater.The growth of microalgae and the nutrient removal by microalgae Botryococcus sp. in domestic wastewater are investigated by using Mathematica software. As a result, the estimation of the microalgae Botryococcus sp. growth and nutrient removal in wastewater can be obtained and thus the microalgae Botryococcus sp.are suitable for treating domestic wastewater

Non-Linearity Flux of Fractional Transport Density Equation in Traffic Flow with Solutions

In the present paper, we derive and solve the space-fractional traffic flow model which is considered as a generalization of the transport density equation. Based on the fundamental physical principles on finite-length highway where the number of vehicles is conserved, without entrances or exits, we construct a fractional continuity equation. As a limitation of the classical calculus, the continuity equation is constructed based on truncating after the first order of Taylor expansion, which means that the change in the number of vehicles is linear over the finite-length highway. However, in fractional calculus, we prove that nonlinear flow is a result of truncating the fractional Taylor polynomial after the second term with zero error. Therefore, the new fractional traffic flow model is free from being linear, and the space now is described by the fractional powers of coordinates, provided with a single variable measure. Further, some exact solutions of the fractional model are generated by the method of characteristics. Remarkably, these solutions have significant physical implications to help to make the proper decisions for constructing traffic signals in a smart city