Showing papers by "Al Zawiya University published in 2015"

A Four-Leg Matrix Converter Ground Power Unit With Repetitive Voltage Control

Abstract: In this paper, a four-leg matrix converter is proposed as the power conversion core for aircraft ground power unit (GPU) applications. This structure allows easy management of unbalanced and nonlinear loads with minimal disruption of the power supply operation. A hybrid repetitive-traditional control system is proposed to regulate the output voltage of the GPU. This solution reduces the steady-state tracking error, maintaining fast dynamic characteristics, and increases the stability of the converter compared to conventional approaches. Simulations and experimental results from a 7.5-KW converter prototype are presented to verify the operation of the proposed configuration and to prove the effectiveness of the solution.

Top-Down and Bottom-Up Approaches in 3D Printing Technologies for Drug Delivery Challenges.

Abstract: 3-Dimensional printing (3DP) constitutes a raft of technologies, based on different physical mechanisms, that generate a 3-dimensional physical object from a digital model. Because of its rapid fabrication and precise geometry, 3DP has gained a prominent focus in biomedical and nanobiomaterials research. Despite advancements in targeted, controlled, and pulsatile drug delivery, the achievement of site-specific and disease-responsive drug release and stringent control over in vivo biodistribution, are still some of the important, challenging areas for pharmaceutical research and development and existing drug delivery techniques. Microelectronic industries are capable of generating nano-/microdrug delivery devices at high throughputs with a highly precise control over design. Successful miniaturizations of micro-pumps with multireservoir architectures for delivery of pharmaceuticals developed by micro-electromechanical systems technology were more acceptable than implantable devices. Inkjet printing technologies, which dispense a precise amount of polymer ink solutions, find applications in controlled drug delivery. Bioelectronic products have revolutionized drug delivery technologies. Designing nanoparticles by nanoimprint lithography showed a controlled drug release pattern, biodistribution, and in vivo transport. This review highlights the "top-down" and "bottom-up" approaches of the most promising 3DP technologies and their broader applications in biomedical and therapeutic drug delivery, with critical assessment of its merits, demerits, and intellectual property rights challenges.

Reducing Cement Contents of Paving Blocks by Using Mineral Waste and By-product Materials

Abstract: In the production of conventional paving blocks, it is usual to use a minimum of 210 kg/m3 of cement. However, when portland cement is produced, it impacts negatively on the environment due to carbon dioxide emissions. Therefore, this paper investigates the use of waste and by-product materials, such as run-of-station ash (ROSA), basic oxygen slag (BOS), ground granulated blast-furnace slag (GGBS), plasterboard gypsum (PG), and cement bypass dust (BPD) to reduce the amount of cement in paving blocks. The combinations of binary and ternary blends in different mixes are considered. Tensile strength, skid/slip and freeze/thaw resistance of paving blocks, verified that a cementitious mix containing ROSA up to 60%, GGBS up to 55%, BPD up to 25%, and plasterboard gypsum PG up to 5% by weight can replace portland cement without having any substantial impact on the strength or durability of the blocks. XRD and XRF tests of selected mixes have been presented and discussed. Concrete blocks prepared with OP...

Chemometrics optimized extraction procedures, phytosynergistic blending and in vitro screening of natural enzyme inhibitors amongst leaves of Tulsi, Banyan and Jamun

Abstract: Background: Tulsi, Banyan, and Jamun are popular Indian medicinal plants with notable hypoglycemic potentials. Now the work reports chemo-profiling of the three species with in - vitro screening approach for natural enzyme inhibitors (NEIs) against enzymes pathogenic for type 2 diabetes. Further along with the chemometrics optimized extraction process technology, phyto-synergistic studies of the composite polyherbal blends have also been reported. Objective: Chemometrically optimized extraction procedures, ratios of polyherbal composites to achieve phyto-synergistic actions, and in - vitro screening of NEIs amongst leaves of Tulsi, Banyan, and Jamun. Materials and Methods: The extraction process parameters of the leaves of three plant species (Ficus benghalensis, Syzigium cumini and Ocimum sanctum) were optimized by rotatable central composite design of chemometrics so as to get maximal yield of bio-actives. Phyto-blends of three species were prepared so as to achieve synergistic antidiabetic and antioxidant potentials and the ratios were optimized by chemometrics. Next, for in vitro screening of natural enzyme inhibitors the individual leaf extracts as well as composite blends were subjected to assay procedures to see their inhibitory potentials against the enzymes pathogenic in type 2 diabetes. The antioxidant potentials were also estimated by DPPH radical scavenging, ABTS, FRAP and Dot Blot assay. Results: Considering response surface methodology studies and from the solutions obtained using desirability function, it was found that hydro-ethanolic or methanolic solvent ratio of 52.46 ΁ 1.6 and at a temperature of 20.17 ΁ 0.6 gave an optimum yield of polyphenols with minimal chlorophyll leaching. The species also showed the presence of glycosides, alkaloids, and saponins. Composites in the ratios of 1:1:1 and 1:1:2 gave synergistic effects in terms of polyphenol yield and anti-oxidant potentials. All composites (1:1:1, 1:2:1, 2:1:1, 1:1:2) showed synergistic anti-oxidant actions. Inhibitory activities against the targeted enzymes expressed in terms of IC 50 values have shown that hydro-ethanolic extracts in all cases whether individual species or composites in varying ratios gave higher IC 50 values thus showing greater effectivity. Conclusion: Current research provides the state-of-the-art of search of NEIs amongst three species by in-vitro assays which can be further utilized for bioactivity-guided isolations of such enzyme inhibitors. Further, it reports the optimized phyto-blend ratios so as to achieve synergistic anti-oxidative actions.

Formulation, Characterization and In vitro Evaluation of Capecitabine Loaded Polycaprolactone-Chitosan Nanospheres

Abstract: The aim of this study is to formulate the capecitabine loaded nanospheres of polycaprolactone-chitosan, cross linked with Tripolyphosphate for anticancer therapy, in order to enhance the bioavailability and to reduce the dose frequency. Formulations of capecitabine loaded nanospheres were prepared by double emulsion solvent evaporation and solvent diffusion methods. Fourier transmission infrared spectroscopy studies indicated no chemical interaction between drug and polymer. Scanning electron microscopy showed nanospheres having a discrete spherial structure without aggregation. The average particle size was found as 616 ± 110 to 713 ± 115 nm. In vitro release studies were performed by the dialysis membrane method. All the drug loaded batches were follwed zero order and sustained drug release over a period of 24 hrs. DOI: http://dx.doi.org/10.3329/bpj.v17i1.22309 Bangladesh Pharmaceutical Journal 17 (1): 18-24, 2014

Sequence stratigraphic analysis of fluvial deposits using facies characterization and wireline log correlation: case of the late Early-early Middle Devonian Snake Cave Interval, Darling Basin, Australia

Abstract: In this article, we present the application of wireline log correlation for sequence stratigraphic analysis to the late Early to early Middle Devonian Snake Cave Interval in the Neckarboo Sub-basin (DM Kewell East DDH-1 well) and Hillston Trough (DM Mossgiel DDH-1 well), Darling Basin. The results of an integrated study using characterising wireline log signatures (gamma ray, sonic, resistivity shallow, long spaced neutron and limest neutron porosity) and core description data supplemented by limited palaeontological reports indicate that three major upper Lower to lower Middle Devonian cycles have controlled sedimentation of this stratigraphic succession. We distinguished seven core sedimentary facies, which were grouped into six electrofacies defined by wireline log signatures. The electrofacies were defined by describing and analysing the graphic gamma ray logs using basic geometrical shapes, such as bell, serrated bell, funnel, serrated funnel, cylinder (block) and linear. Six electrofacies informally named electrofacies SA, SB, SC, SD, SE and SF correspond to seven core facies (MS1-MS7), which have progressively greater sandstone/shale ratios and better electrofacies quality. These electrofacies are characterised as follows: electrofacies SA corresponds to the conglomeratic braided channel-fill, electrofacies SB corresponds to channel lag and point bar, electrofacies SC corresponds to crevasse splay sandstones and flood-plain fines, electrofacies SD corresponds to multistorey fluvial channel-fills, electrofacies SE corresponds to sandy braided channel-fills and electrofacies SF corresponds to distributary channel sands and local small delta-plain. The upper Lower to lower Middle Devonian sequence (Snake Cave Interval) of the Neckarboo Sub-basin and Hillston Trough is characterised by two major third-order sequences (Snake Cave sequence 1 and Snake Cave sequence 2) that consist of ten systems tracts and ten sequence surfaces. Snake Cave sequence 1 (SCS1) consists of two cycles with progradational to retrogradational trends (LST1 to TST1 and LST2 to TST2 separated by a marine flooding surface) divided into five sequence surfaces (SBSC1, TS1 MFS1, TS2 and MFS2, in ascending order) as defined by wireline log signatures. One cycle has progradational, retrogradational to aggradational trends (LST3, TST3 to HST1) and has seven sequence surfaces (e.g. MFS2, LST3, TS3, MFS3 and SBSC2, in ascending order). Snake Cave sequence 2 (SCS2) consists of one unit with progradational, retrogradational to aggradational trends (LST4, TST4 and HST2, in ascending order) with three sequence surfaces (e.g. SBSC2, TS4 and MFS4). No TST4 and HST packages were observed, and the MFS4 is poorly developed. The recognition of sedimentological sequence stratigraphic changes above and below marine flooding surfaces (MFS1-4), where deposition sequences have been defined without adequate biostratigraphic control, is easy since depositional sequence and bounding surface correlation can always be clearly demonstrated. A sequence stratigraphic architecture that can be used to accentuate and strengthen Darling basin exploration also documents significant changes in the local and regional tectonostratigraphic setting.

Numerical Simulation of Film Cooling Over Flat Plate

Abstract: The effect of film cooling over flat plate is investigated using the commercial CD code; Fluent 6.3. The computational domain includes the coolant supply tube as well as the main mixing region. A tube L/D of 4 and injection angles of (30 o , 60 o , and 90 o ) were employed for blowing ratio of (0.33, 0.5, and 1.67), and a density ratio of 1.14. Adiabatic film cooling effectiveness distributions were also determined for inline and staggered arrangements. The main observation from this study that the 30 o hole gave larger effectiveness values than 60 o and 90 o at the blowing ratio of 0.33 with the same length-to-diameter ratio. The maximum effectiveness was achieved with a blowing ratio of 0.5. The results show that the increase of blowing ratio negatively affects film cooling, such that for the blowing ratio of 1.67 the injected coolant tends to lift off from the wall due to the increase of the wall normal momentum. The comparisons for numerical results with experimental data are presented.

Higher-Order Compact-Flow Field-Dependent Variation (HOC-FDV) Method for Solving Two-Dimensional Navier-Stokes Equations

Abstract: In this article, a new, higher-order accurate method, namely higher-order compact-flow field-dependent variation (HOC-FDV) method, has been developed to solve two-dimensional Navier-Stokes equations The HOC-FDV scheme is of third-order accuracy in time and fourth-order in space The spatial derivatives in the flow field-dependent variation (FDV) equations proposed by Chung are approximated using higher-order compact (HOC) Hermitian (Pade) scheme The solution procedure at each time step consists of a system of block tri-diagonal matrices which can be solved efficiently in a standard manner Several numerical examples are tested to examine the accuracy and capability of the new scheme to capture the shock and to simulate accurately separation and discontinuity

Scale invariant feature transform evaluation in small dataset

Abstract: This paper investigates how we can achieve object recognition in an image by looking at some examples of training images. Scale Invariant Feature Transform (SIFT) is one proposal method to detect features in an image and then can use those features to distinguish between different objects. Therefore, my aim was to implement SIFT code to do recognition tasks using simple thresholding and evaluating this algorithm to find its strength and weakness points for a small dataset. The challenge here is to find the best threshold for examples of training images, which can work properly with query images.

Natural convection heat transfer in vertical triangular subchannel in Zirconia-water nanofluid

Abstract: Natural convection heat transfer in vertical triangular sub-channel has important role in cooling mechanism of the APWR and the PHWR nuclear reactors. Unfortunately, natural convection correlation equations for such geometry are scarcely available. Recent studies showed that ZrO2-water nanofluid has a good prospect to be used in the nuclear reactor technology due to its low neutron absorption cross section. Although several papers have reported transport properties of ZrO2-water nanofluids, practically there is no correlation equation for predicting natural convection heat transfer in a vertical triangular sub-channel in ZrO2-water nanofluid. Therefore, a study for finding such heat transfer correlation equation has been done by utilizing Computational Fluid Dynamics software and reported in this paper. In the study, natural convection heat transfer in a vertical triangular sub-channel has been simulated at several values of heat transfer flux within 9.1 to 30.9 kW/m2 range and ZrO2 concentrations of 0 (pure water), 0.27, and 3 volume-% of ZrO2. The study shows that the ZrO2 concentration has no significant influence to the natural convection heat transfer at those concentration levels. The obtained theoretical heat transfer correlation equations were verified through experiment, and they showed very similar results. The correlation equations are reported in this paper.