13 research outputs found
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