Enhancement of electron heating in an ECR trap having a mixed multipole field - A Monte Carlo study

In electron cyclotron resonance (ECR) ion sources, confinement of ions and electrons is achieved with the help of an axial field in combination with a multipolar field. Generally sextupoles are used for this purpose. In a few sources, quadrupoles and octupoles also have been used. But sextupoles have been found to be most useful. We have investigated whether a combination of different multipoles can improve the performance of an ECR trap. A mixture of a sextupolar field and a dipole field has been found to enhance the electron heating to a large extent.     

Peroxidase-mediated oxidative coupling of 1-naphthol: characterization of polymerization products

The oxidative polymerization of 1-naphthol was investigated in the presence of horseradish peroxidase (HRP). Naphthol polymerization products (NPP) were characterized for their relative polarity using octanol--water partitioning experiments and reverse-phase high pressure liquid chromatography, for structure using size exclusion chromatography and liquid chromatography-mass spectrometry (LC/MS), and for ecotoxicity using inhibition of bacterial bioluminescence. Peroxidase addition resulted in the production of soluble and insoluble NPP. Soluble NPP was predominantly more polar than the parent naphthol and comprised of trimers and tetramers. Insoluble NPP oligomers included dimers, trimers and tetramers. The net aqueous-phase toxicity was significantly reduced due to polymer formation and subsequent precipitation. A reaction model deduced from the LC/MS fragmentation patterns of trimeric naphthol was proposed for NPP formation. Results from this study suggest that HRP-mediated treatment of naphthol contaminated soils can achieve risk reduction through (i) the formation of large hydrophobic oligomers that are immobilized on the soil matrix; and (ii) reduction in aqueous-phase toxicity due to polymer precipitation.     

Effect of grain size on the thermoelectric conversion efficiency of semiconductor alloys at high temperature

The theoretical increase in the thermoelectric figure of merit of silicon-germanium alloy at 1000 K which would accompany a reduction in material grain size is calculated. Assuming that acoustic phonon scattering is the dominant scattering mechanism, the improvement in the conversion efficiency compared with single crystal values is estimated to be 14 per cent and 30 per cent for n-type Si₈₀Ge₂₀ alloy with grain sizes of 10 μm and 0·1 μm, respectively.     

General criterion of fracture of cracked plates

International Journal of Fracture -     

Development of a continuous membrane nanobubble generation method applicable in liquid food processing

A novel continuous nanobubble generation method was developed using a commercial ceramic membrane as a nanobubble generator. CO₂ and air were infused externally across the ceramic membrane (pore size 50 nm) into the water flowing inside the ceramic membrane tube. Infusion of each gas was done in a single (20 s) and multiple passes (180 s) at 20–21°C. Results showed that gaseous nanobubbles could be generated even in a single pass. Low power ultrasound (200 kHz, 30W) was applied for the rapid assessment of nanobubble stability. Single-pass ultrasound treatment of the samples was carried out at two levels: 2.6 and 5.1 J mL⁻¹. Among the samples in which gases were infused for multiple passes, air nanobubbles were found more stable than CO₂. In contrast, an opposite trend was observed in those samples in which gases were infused in the single-pass only (20 s). This process has the potential to be applied to food processing industries, such as to enhance the products’ sensory attributes, the efficiency of membrane separation, food drying and liquid food transportation systems.     

Interacting policies in power systems: Renewable subsidies and a carbon tax

Without careful planning and design, energy policies like carbon taxes and renewable subsidies like production tax credits undercut one another in unanticipated ways. We examine how a carbon tax interacts with PTCs by simulating an electricity market using the IEEE RTS model with a carbon tax of $38/tonCO2e and a PTC of $23/MWh. The results show that PTCs work against the carbon tax by both lowering average energy prices and altering the generator dispatch.     

Dark satellite image enhancement using knee transfer function and gamma correction based on DWT–SVD

In this paper, an improved and simple approach for enhancement of dark and low contrast satellite image based on knee function and gamma correction using discrete wavelet transform with singular value decomposition (DWT–SVD) has been proposed for quality enhancement of feature. In addition, this method can also process the high resolution dark or very low contrast images, and offers best enhanced result using tuning parameter of Gamma. The technique decomposes the input image into four frequency subbands by using DWT and estimates the singular value matrix of the low–low subband image, and then compute the knee transfer function using gamma correction for further improvement of the LL component. Afterward, processed LL band image undergoes IDWT together with the unprocessed LH, HL, and HH subbands to generate an appropriate enhanced image. Although, various histogram equalization approaches has been proposed in the literature, they tend to degrade the overall image quality by exhibiting saturation artifacts in both low- and high-intensity regions. The proposed algorithm overcomes this problem using knee function and gamma correction. The experimental results show that the proposed algorithm enhances the overall contrast and visibility of local details better than the existing techniques.     

Water sorption and glass transition properties of spray dried lactose hydrolysed skim milk powder

The moisture sorption behaviour and glass transition temperature of spray dried skim milk powder with hydrolysed lactose (SMPHL) were determined. Spray drying of skim milk with hydrolysed lactose resulted in very low cyclone recovery of 25% and a large amount of powder remained stuck inside the spray dryer. The equilibrium moisture content of SMPHL was lower than that of lactose for each range of water activity when humidified for 21 days at 23 °C using saturated salt solutions. Unlike lactose, SMPHL did not lose water when the water activity exceeded 0.432 and no crystallization was noticed at water activity ?0.753. The sorption isotherm data for SMPHL fitted well with the BET and GAB models with monolayer moisture contents of 7.55 and 8.27 g/100 g, respectively. The glass transition temperature of anhydrous SMPHL was 49 °C. The critical water activity and moisture content for SMPHL were 0.15 and 2.4 g/100 g dry solid, respectively. The low critical values indicated hydrolysis of lactose necessities maintenance of very low moisture of powder for its long-term stability.     

Unsteady flow and heat transfer of a ferrofluid between two rotating,vertical moving and stretching disks

Unsteady flow and heat transfer of a magnetic fluid between two rotating disks is investigated. Both the disks are stretchable and the lower disk moves in the vertical direction. A new approach of similarity transformation is adopted to transform the equation of continuity, momentum, and the energy equation into ordinary nonlinear coupled differential equations. The numerical solution of the converted nonlinear differential equations is obtained using the finite element method. The effects of magnetization force, rotational viscosity, Prandtl number, and Eckert number on the velocity and temperature distributions are studied. The impact of stretching, movement, and rotation of the disk is also considered in this computational study. The skin friction coefficients and heat transfer rate on the lower disk for different physical parameters are calculated. Different types of motion of the disks and the magnetization force are crucial aspects in the stress distribution and heat transfer rate near the lower disk.