Robust radar target classifier using artificial neural networks

In this paper an artificial neural network (ANN) based radar target classifier is presented, and its performance is compared with that of a conventional minimum distance classifier. Radar returns from realistic aircraft are synthesized using a thin wire time domain electromagnetic code. The time varying backscattered electric field from each target is processed using both a conventional scheme and an ANN-based scheme for classification purposes. It is found that a multilayer feedforward ANN, trained using a backpropagation learning algorithm, provides a higher percentage of successful classification than the conventional scheme. The performance of the ANN is found to be particularly attractive in an environment of low signal-to-noise ratio. The performance of both methods are also compared when a preemphasis filter is used to enhance the contributions from the high frequency poles in the target response.     

Exploratory study on power-efficient silicon nano-wire dynamic NMOSFET/PMESFET logic

The latest techniques in fabricating silicon-based, vertical surrounding gate MOSFETs (SGFET) instigate the pathway towards building the next generation ultra large-scale integration (ULSI). The study shows the design and optimisation of surrounding gate n-channel MOSFETs and p-channel MESFETs used in dynamic differential domino circuits suitable for an area-efficient technology. Three-dimensional device simulations investigate the maximum device transconductance and minimum OFF current of vertical, metal-gated nano-wire NMOSFETs and PMESFETs as a function of wire radius and doping concentration. Two-dimensional process simulations are carried out on the optimum transistor designs, and non-ideal device characteristics are measured. A family of differential dynamic circuits composed of a two-input AND (OR), and two-input XOR gates and a full adder are built to measure worst-case pre-charge and evaluate function delays, power dissipation and layout area     

The effect of sintering temperature on some properties of Cu-SiC composite

Copper matrix composites reinforced with 1 wt.%, 2 wt.%, 3 wt.% and 5 wt.% SiC particles were fabricated by powder metallurgy method. Cu and Cu-SiC powder mixtures were compacted with a compressive force of 280 MPa and sintered in an open atmospheric furnace at 900-950 °C for 2 h. Within the furnace compacted samples were embedding into the graphite powder. The presence of Cu and SiC components in composites was verified by XRD analysis. Optical and SEM studies showed that Cu-SiC composites have a uniform microstructure in which silicon carbide particles are distributed uniformly in the copper matrix. The results of the study on mechanical and electrical conductivity properties of Cu-SiC composites indicated that with increasing SiC content (wt.%), hardness increased, but relative density and electrical conductivity decreased. The highest electrical conductivity of 98.8% IACS and relative density of 98.2% were obtained for the Cu-1 wt.%SiC composite sintered at 900 °C and this temperature was defined as the optimum sintering temperature.     

Influence of metal salts in reaction medium on performance enhancement of novel aliphatic–aromatic-based polyamide thin-film composite osmosis membranes

In this study, we report an easy and novel way to develop high flux aliphatic–aromatic-based thin-film composite (TFC) polyamide osmosis membranes by addition of inorganic metal salts with amine reactants in the reaction system of polyethylene imine (PEI) and 1,3-benzene dicarbonyl chloride. Inorganic metal salts like CuSO₄, NiSO₄, MgSO₄, and Al₂(SO₄)₃ added to block some of the amine groups of PEI through complexation which in turn changes the polycondensation reaction kinetics of amine acid chloride reaction. The prepared membranes were characterized using water contact angle and atomic force microscopy studies and the performances were evaluated both in reverse osmosis and forward osmosis mode. In presence of metal salts in reaction interface, the performance of TFC membranes was greatly enhanced and the optimum metal salt concentration was identified for individual metal salts for maximum performance enhancement. The effects of different anions for same metal ion and different molecular weight of PEI were evaluated on composite polyamide membrane performances. Water permeability (flux) of 63.48 L m^?2 h^?1 was achieved upon inorganic salt addition compared to the unmodified TFC membranes with flux of 42.1 L m^?2 h^?1 at similar salt rejection of ~95%. Based on the new findings, a conceptual model was proposed to explain the role of metal ion in amine solution on the resulting characteristics of aromatic–aliphatic type polyamide–polysulfone composite membrane.     

On the choice of hexagonal boron nitride for high pressure phase transformation using the catalyst solvent process

The degree of three-dimensional ordering, particle-size distribution and purity of two types of hexagonal boron nitride have been studied with a view to establish any possible correlation between these characteristics with the conversion of hexagonal form to cubic phase at high pressure and high temperature using magnesium as the catalyst solvent. The crystalline phases formed at high pressure and high temperature have been studied and the dependence of degree of graphitization of boron nitride and purity on the cubic boron nitride conversion discussed.     

Foaming in simulated radioactive waste

Radioactive waste treatment process usually involves concentration of radionuclides before waste can be immobilized by storing it in stable solid form. Foaming is observed at various stages of waste processing like SRAT (sludge receipt and adjustment tank) and melter operations. This kind of foaming greatly limits the process efficiency. The foam encountered can be characterized as a three-phase foam that incorporates finely divided solids (colloidal particles). The solid particles stabilize foaminess in two ways: by adsorption of biphilic particles at the surfaces of foam lamella and by layering of particles trapped inside the foam lamella. During bubble generation and rise, solid particles organize themselves into a layered structure due to confinement inside the foam lamella, and this structure provides a barrier against the coalescence of the bubbles, thereby causing foaming. Our novel capillary force balance apparatus was used to examine the particle-particle interactions, which affect particle layer formation in the foam lamella. Moreover, foaminess shows a maximum with increasing solid particle concentration. To explain the maximum in foaminess, a study was carried out on the simulated sludge, a non-radioactive simulant of the radioactive waste sludge at SRS, to identify the parameters that affect the foaming in a system characterized by the absence of surface-active agents. This three-phase foam does not show any foam stability unlike surfactant-stabilized foam. The parameters investigated were solid particle concentration, heating flux, and electrolyte concentration. The maximum in foaminess was found to be a net result of two countereffects that arise due to particle-particle interactions: structural stabilization and depletion destabilization. It was found that higher electrolyte concentration causes a reduction in foaminess and leads to a smaller bubble size. Higher heating fluxes lead to greater foaminess due to an increased rate of foam lamella generation in the sludge system.     

A comparative study of borided pure niobium, tungsten and chromium

Pure niobium (Nb), tungsten (W) and chromium (Cr) were boronized at 940 °C for 2, 4 and 8 h. The borided samples were characterized by X-ray diffraction, Scanning electron microscope and microhardness tests. Tribological investigation was conducted. X-ray study showed the presence of NbB₂, WB, and CrB. The hardnesses of boride layers formed on the pure Nb, W and Cr were 2500, 2500 and 1700 HV, respectively, whereas the hardnesses of the pure Nb, pure W and pure Cr were 110, 445 and 115 HV, respectively. Nb boride layers ranged in thickness from 8 to 22 μm, whereas W boride layers ranged in thickness from 10 to 42 μm, and the thickness of Cr boride layer varied from 4 to 12 μm with boronizing time. The boriding of W resulted in thicker boride layer compared to the boriding of Nb and Cr at given time. The frictional behaviour and wear mechanicms differ in modes and scales.     

Total aflatoxins in complementary foods produced at community levels using locally available ingredients in Ethiopia

This study was conducted to determine the occurrence and levels of total aflatoxins in complementary foods (CFs) and their ingredients. A total of 126 samples collected from 20 Districts from Amhara, Tigray, Oromia, and Southern Nations Nationalities and Peoples (SNNP) regions were analysed for levels of total aflatoxins using enzyme linked immunosorbent assay (ELISA). Aflatoxins were detected in 62 out of 66 pre-milling samples with mean range of 0.3–9.9 µg/kg. Aflatoxins were also detected in 19 out of 20 post-production CFs and in all of the one-month stored CFs at households and grain banks, with a mean range of 0.5–8.0, 3.6–11.3, and 0.2–12.4 µg/kg, respectively. Overall, 3 out of 126 samples exceeded the maximum limit (10 µg/kg). Although most aflatoxin levels were below the maximum limit and thus considered to be safe for consumption, more effort should be implemented to reduce contamination, as these CFs are intended for consumption by young children.