Fingerprint Image Compression Using Wavelet Transform

The fingerprint is considered to be the most reliable kind of personal identification because it cannot be forgotten, misplaced, or stolen. Fingerprint authorization is potentially the most affordable and convenient method of verifying a person's identity. Storage of fingerprint image databases needs allocation of huge secondary storage devices. To reduce the increasing demand on storage space, efficient data compression techniques are needed. In addition to that, the exchange of fingerprint images between the governmental agencies could be done fast. The compression algorithm must also preserve original information in the original image. Digital image compression based on the ideas of subband decomposition or discrete wavelet transform (DWT) has received much attention in recent years. In fact, wavelet refers to a set of basic function, which is recursively defined form, a set of scaling coefficients and scaling function. Discrete Wavelet Transform CDWT) represents images as a sum of wavelet function on different resolution level. Essential for wavelet transform can be composed of any function that satisfies requirements of multi-resolution analysis. It means that there exists a large selection of wavelet families depending on choice of wavelet function. The objective of this study is to evaluate a variety of wavelet filters using Wavelet toolbox for selecting the best wavelet filters to be used in compress and decompress of selected fingerprint images. Therefore a two-dimensional wavelet decomposition, quantization and reconstruction using several families of filter banks were applied to a set of fingerprint images. The results show that no specific wavelet filter performs uniformly except for Biorthogonal and Symlets, and that is using the matching technique. The result shows that at a threshold value equal of 160 and decomposition level 3 with a wavelet filter sym4, there is no difference between the original and reconstructed image. This study concludes that using wavelet filters sym4 and bior3.7 can achieve compression ratio 27: 1 with PSNR 20.36 dB and 17: 1 with PSNR 21.88 dB respectively. These values indicate that using these filters, the quality of the reconstructed fingerprint still exist

Removal of carbon dioxide from high pressure natural gas by adsorption on activated carbons

The presence of carbon dioxide (CO2) in raw natural gas is a major challenge for the natural gas industry because it decreases the heating value of the natural gas and promotes corrosion in the piping materials used for transportation. Today, the natural gas industry is dominated by the energy-intensive amine chemical absorption process to remove the CO2, however, pressure swing adsorption process has the potential to provide a sustainable and low energy penalty alternative. This research investigated the feasibility of using activated carbons as solid adsorbents for pressure swing adsorption process to remove CO2 from high pressure and high CO2 natural gas. Two sets of 14 samples of activated carbons were synthesised from two different precursors: date pits biomass and coal tar pitch. A two-step chemical activation process with potassium hydroxide (KOH) was used to convert the date pits biomass into activated carbons, and a one-step KOH chemical activation process was used to produce activated carbons from the coal tar pitch. Nitrogen adsorption based characterisation revealed that both series of activated carbons were dominated by micropores when prepared with various KOH to carbon ratios (ranging from 1 to 4) and various activation temperatures (600 to 800 oC). However, some mesoporosity was seen at an activation temperature of 900 oC. All the samples were performance tested for CO2 and methane (CH4) working adsorption capacities by gravimetric measurement. These tests revealed higher CO2 working capacities compared to that of CH4, confirming that the activated carbons have a potential use as solid adsorbents for CO2/CH4 separation. The performance test conditions were based on the process conditions of a South Oman gas field (100 bar pressure, 50 oC temperature and 20% CO2 content). The CO2 uptake and the CH4 uptake by the activated carbons were found to positively correlate with the BET surface area and micropore volume of the activated carbons. However, larger micropores in the activated carbons (>1.6 nm) were found to be less favourable for CO2 adsorption. The effect of water on CO2 uptake and CH4 uptake of the activated carbons were investigated from two aspects: as a contaminant and as CO2 selectivity enhancement agent. A small amount of water (10% in the vapour phase) was used to investigate water as a contaminant and showed a negative effect on both CO2 and CH4 adsorption capacities. A large amount of pre-adsorbed water (50%) increased the CO2/CH4 working capacity ratios at high pressure indicating CO2/CH4 selectivity enhancement but reduced CO2 uptake capacity. CO2 and CH4 adsorption isotherms were successfully measured using a high pressure volumetric analyser. The measured isotherms were best fitted with the Dual Site Langmuir (DSL) model compared to the Langmuir or Sips models. The extended DSL model was used to predict the binary mixed gas (CO2 and CH4) adsorption after gravimetric measurements of total adsorption were employed to select the right pair of the extended DSL equation to overcome the issue of site matching. The binary gas adsorption calculations showed favourable adsorption for CO2 over CH4 as CO2 partial pressure in the mixture increased. However, the co-adsorption of CH4 in the activated carbon also increased as CH4 partial pressure increased which would decrease the purity of the removed CO2 in a Pressure Swing Adsorption (PSA) process. In conclusion, the activated carbons synthesised from low cost precursors by simple chemical activation method showed good potential for separating CO2 from CH4. This potential was demonstrated by CO2/CH4 working capacity ratios higher than one for most samples, and confirmed by DSL adsorption model of mixed gas (CO2 and CH4) adsorption on activated carbons. Future work could include improving the activated carbon mechanical strength, reducing CH4 adsorption in addition to designing a PSA process to demonstrate the expected energy saving

Minimally Invasive Microneedle Array Electrodes Employing Direct Electron Transfer Type Glucose Dehydrogenase for the Development of Continuous Glucose Monitoring Sensors

Closed loop systems hinge on the accuracy and precision of the continuous glucose monitoring sensors. Most of the commercially available continuous glucose monitoring sensors is implanted subcutaneously for a period of 7-14 days. The subsequent biofouling effects have implications on the performance of the sensors over time especially at low glucose concentrations. In addition, the commercially available sensors are sensitive to the presence of interfering species such as acetaminophen in the skin compartment. We report here on the marriage of minimally invasive, continuous glucose sensors and a direct electron transfer type glucose dehydrogenase enzymatic system. Whilst the microneedles here are designed to sit in the dermal interstitial fluid over a 24-48 hour period to minimize the biofouling effect, the direct electron transfer enzyme allows operation of the electrochemical sensor at lower potentials to minimize the effect of interference. The microneedle structure design also enables the use of compensation electrodes for background subtraction to further nullify the effects of interference

A survey on probabilistic broadcast schemes for wireless ad hoc networks

Broadcast or flooding is a dissemination technique of paramount importance in wireless ad hoc networks. The broadcast scheme is widely used within routing protocols by a wide range of wireless ad hoc networks such as mobile ad hoc networks, vehicular ad hoc networks, and wireless sensor networks, and used to spread emergency messages in critical scenarios after a disaster scenario and/or an accidents. As the type broadcast scheme used plays an important role in the performance of the network, it has to be selected carefully. Though several types of broadcast schemes have been proposed, probabilistic broadcast schemes have been demonstrated to be suitable schemes for wireless ad hoc networks due to a range of benefits offered by them such as low overhead, balanced energy consumption, and robustness against failures and mobility of nodes. In the last decade, many probabilistic broadcast schemes have been proposed by researchers. In addition to reviewing the main features of the probabilistic schemes found in the literature, we also present a classification of the probabilistic schemes, an exhaustive review of the evaluation methodology including their performance metrics, types of network simulators, their comparisons, and present some examples of real implementations, in this paper

Ovarian Hyperstimulation and Maternal Virilisation with Successful Pregnancy Outcome: A case report

Hyperreactio luteinalis (HL) and ovarian hyperstimulation syndrome (OHSS) during pregnancy are both benign conditions where the ovaries are enlarged with presence of multiple thin-walled cysts. Differential diagnosis is ovarian malignancy. Hyperandrogenism with resultant maternal virilization could be seen in some cases of HL as well as in androgen secreting tumours. We report the case of a 41 years old lady underwent ovulation induction due to secondary infertility. She had recurrent hospital admission with abdominal pain and huge multicystic enlargement of both ovaries. She developed virilisation features by 35 weeks of pregnancy. Lower segment caesarean section was done at 36 weeks gestation for breech presentation with intra uterine growth restriction. Magnetic resonance imaging (MRI) confirmed benign nature of the cysts. Ovarian cysts and hyperandrogenism gradually resolved by three months of delivery. Awareness, judicious imaging and close monitoring in such cases can result in live birth and avoid oophorectomies. Keywords: Hyperandrogenism; Hirsuitism; Virilism; Polycstic ovary syndrome; Ovarian hyper stimulation; Ovulation induction; Hyperreactio luteinalis; Ovarian cysts

Impact of protein-polymer interactions in the antimicrobial activity of lysozyme/poly(3,4-ethylenedioxythiophene) biocapacitors

Biocapacitors constructed by combining lysozyme (LYZ) and poly(3,4-ethylenedioxythiophene) (PEDOT) retained the bactericidal activity of the protein when this was encapsulated within the polymeric matrix but lost the antimicrobial behaviour when the LYZ was adsorbed onto the polymer. In this work we use atomistic Molecular Dynamics simulations to examine the influence of protein···polymer interactions in the bactericidal activity of LYZ-containing biocapacitors. Results show that the anisotropic forces exerted by oxidized PEDOT chains on the adsorbed protein induce small structural changes that locally affect at the active centre, breaking the intra-residue interactions associated with the antibacterial mechanism. Conversely, isotropic polymer···protein interactions in biocapacitors with encapsulated LYZ do not affect the stability of the active centre. These observations suggest that the strong repulsive or attractive forces between p-doped polymer chains and the positively or negatively charged LYZ residues, respectively, are the only ones responsible for the protein activity.Peer ReviewedPostprint (author's final draft