77 research outputs found
Plant Identification based on Fractal Refinement Technique (FRT)
AbstractWe propose here a new algorithm for plant classification and identification based on fractal dimension. It is a simple and efficient technique for identifying plants using three levels of fractal refinement on leaf images. Contour, Contour-Nervure and Nervure fractal dimensions are computed and are used in the first, second and third level of refinement respectively. A 50 set species with each set containing 10 samples are used for training the algorithm. The performance of the algorithm was examined with a test set of 500 leaves arbitrarily selected from different groups of species. The fault acceptance rate (FAR), the fault rejection rate (FRR) and the classification accuracy of the algorithm were analyzed experimentally and demonstrated that the proposed method has an accuracy rate of 84%
Vortex shedding patterns, their competition, and chaos in flow past inline oscillating rectangular cylinders
The flow past inline oscillating rectangular cylinders is studied numerically
at a Reynolds number representative of two-dimensional flow. A symmetric mode,
known as S-II, consisting of a pair of oppositely-signed vortices on each side,
observed recently in experiments, is obtained computationally. A new symmetric
mode, named here as S-III, is also found. At low oscillation amplitudes, the
vortex shedding pattern transitions from antisymmetric to symmetric smoothly
via a regime of intermediate phase. At higher amplitudes, this intermediate
regime is chaotic. The finding of chaos extends and complements the recent work
of Perdikaris et al. [1]. Moreover it shows that the chaos results from a
competition between antisymmetric and symmetric shedding modes. Rectangular
cylinders rather than square are seen to facilitate these observations. A
global, and very reliable, measure is used to establish the existence of chaos.Comment: Submitted to the Physics of Fluid
Temperature dependence of dark current properties of InGaAs/GaAs quantum dot solar cells
Self-assembledIn₀.₅Ga₀.₅As/GaAsquantum dotsolar cell (QDSC) was grown by metal organic chemical vapor deposition. Systematic measurements of dark current versus voltage (I-V) characteristics were carried out from 30 to 310 K. Compared with the reference GaAssolar cell, the QDSC exhibits larger dark current however its ideality factor (n) was smaller, which cannot be straightly interpreted by the conventional diode models. These results are important for the fundamental understanding of QDSC properties and further implementation of new solar cell designs for improved efficiency.The authors would like to acknowledge financial support
from the Australian Research Council and facility support
from the Australian National Fabrication Facility ACT
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Microparticle surface layering through dry coating: impact of moisture content and process parameters on the properties of orally disintegrating tablets
Objectives: The aim of this study was to investigate the influence of process parameters during dry coating on particle and dosage form properties upon varying the surface adsorbed moisture of microcrystalline cellulose (MCC), a model filler/binder for orally disintegrating tablets (ODTs).
Methods: The moisture content of MCC was optimised using the spray water method and analysed using thermogravimetric analysis. Microproperty/macro-property assessment was investigated using atomic force microscopy, nano-indentation, scanning electron microscopy, tablet hardness and disintegration testing.
Key findings: The results showed that MCC demonstrated its best flowability at a moisture content of 11.2% w/w when compared to control, comprising of3.9% w/w moisture. The use of the composite powder coating process (without air) resulted in up to 80% increase in tablet hardness, when compared to the control. The study also demonstrated that surface adsorbed moisture can be displaced upon addition of excipients during dry processing circumventing the need for particle drying before tabletting.
Conclusions: It was concluded that MCC with a moisture content of 11% w/w provides a good balance between powder flowability and favourable ODT characteristics
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Omnidirectional Current Enhancement From Laminated Moth-Eye Textured Polymer Packaging for Large-Area, Flexible III-V Solar Modules
Epitaxial lift-off (ELO) processes have allowed for
cheaper development of mechanically flexible, ultra-thin, and high-
efficiency III-V solar cells. ELO solar cells are natural candidates
for applications where solar cells must conform to curved surfaces
and provide high efficiency and high specific power generation
(W/kg). Such examples include power generation for unmanned
aerial vehicles, electric vehicles, and portable electrical power.
However, when considering these mobile solar applications, large
variations in angle of incidence (AOI) that inevitably occur can
greatly decrease overall system efficiency due to significant Fresnel
reflections. In this article, we demonstrate the integration of moth-
eye antireflection nanostructures on the polymer packaging layer
of ELO solar cell arrays using a low-cost, colloidal self-assembly
process. The moth-eye structures mitigate Fresnel reflections and
increase photocurrent generation over all measured angles of inci-
dence relative to ELO solar cell arrays with traditional untextured
polymer packaging. The nanostructures survive a commercial lam-
ination procedure, an important criterion that must be met to
ensure the feasibility of integration into commercial processing.
Outdoor solar characterization measurements are performed and,
under direct optical illumination, moth-eye textured solar cell ar-
rays show a maximum Isc enhancement of ∼58% at 79° AOI rela-
tive to traditional untextured polymer packaged solar cell arrays,
and when exposed to both direct and diffuse optical illumination a
maximum Isc enhancement of ∼23% at 79° AOI is observed.Center for Dynamics and Control of Material
Influence of Organic Acids on Diltiazem HCl Release Kinetics from Hydroxypropyl Methyl Cellulose Matrix Tablets
The matrix tablets of diltiazem hydrochloride were prepared by direct compression using hydroxypropyl methyl cellulose (HPMC) and various amounts (2.5%, 5.0%, 10% and 20%) of citric acid, malic acid and succinic acid. The characterization of physical mixture of drug and organic acids was performed by Infra-red spectroscopy. An organic acid was incorporated to set up a system bringing about gradual release of this drug. The influence of organic acids on the release rate were described by the Peppas equation: M t /M∞ = Kt n and Higuchi’s equation: Q t = K1t1/2. The addition of organic acids and the pH value of medium could notably influence the dissolution behavior and mechanism of drug-release from matrices. Increasing amounts of organic acid produced an increase in drug release rate, which showed a good linear relationship between contents of organic acid and drug accumulate release (%) in phosphate buffer, pH 7.4. The drug release increased significantly (P < 0.05) with use of succinic acid in tablet formulation. Increasing amounts of succinic acid above 10% produced decreasing values of n and increasing values of k, in a linear relationship, which indicated there was a burst release of drug from the matrix. Optimized formulations are found to be stable upon 3-month study
Photonic system for real-time detection, discrimination, and quantification of microbes in air
We report the results of the non-invasive photonic system AUM for remote detection and characterization of different pathogenic bacterial strains and mixtures. AUM applies the concepts of elastic light scattering, statistical mechanics, artificial intelligence, and machine learning to identify, classify and quantify various microbes in the scattering volume in real-time and, therefore, can become a potential tool in controlling and managing diseases caused by pathogenic microbes
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