Study of spray cooling of a pressure vessel head of a boiling water reactor

The present paper deals with a theoretical analysis of the spray cooling of a Reactor Pressure Vessel (RPV) head in a Boiling Water Reactor (BWR). To this end a detailed computational model has been developed. The model predicts the trajectories, diameters and temperatures of subcooled droplets moving in saturated vapor. The model has been validated through comparison with experimental data, in which droplet temperatures were measured as functions of the distance that they cover in saturated vapor from the moment they leave the sprinkler outlet to the moment they impact on the RPV head inner wall. The calculations are in very good agreement with measurements, confirming the model adequacy for the present study. The model has been used for a parametric study to investigate the influence of several parameters on the cooling efficiency of the spray system. Based on the study it has been shown that one of the main parameters that govern the temperature increase in a subcooled droplet is its initial diameter. Comparisons are also made between conclusions from the theoretical model and observations made through flow and temperature measurements in the plant (Forsmark 1 and 2). One of these observations is that the rate at which the RPV head temperature decreases on the way down from hot to cold standby is constant and independent of the sprinkling flow rate as long as the flow rate is above a certain minimum value. Accordingly, the theoretical model shows that if one assumes that the cooling of the RPV head is through a water film built on the inner wall due to sprinkling, the heat removal rate is only very weakly dependent on the sprinkling flow rate.     

Separating reflections from images by use of independent component analysis.

The image of an object can vary dramatically, depending on lighting, specularities, reflections, and shadows. It is often advantageous to separate these incidental variations from the intrinsic aspects of an image. We describe a method for photographing objects behind glass and digitally removing the reflections from the surface of the glass, leaving the image of the objects behind the glass intact. We describe the details of this method, which employs simple optical techniques and independent component analysis and show its efficacy with several examples.     

Blind inverse gamma correction

The luminance nonlinearity introduced by many imaging devices can often be described by a simple point-wise operation (gamma correction). This paper presents a technique for blindly estimating the amount of gamma correction in the absence of any calibration information or knowledge of the imaging device. The basic approach exploits the fact that gamma correction introduces specific higher-order correlations in the frequency domain. These correlations can be detected using tools from polyspectral analysis. The amount of gamma correction is then estimated by minimizing these correlations.     

Roller compacted concrete with contaminated recycled aggregates

Recycling waste building materials from construction and demolition (C&D) sites is increasingly investigated for economical and environmental reasons. Roller compacted concrete (RCC) is a special dry concrete mix; laid down and compacted like a soil, it is especially used for the construction of massive structures like dams or large horizontal surfaces like road foundation. In this paper, natural concrete slabs were cured in water, sea water, chloride solutions or sulphate solutions and then crushed to obtain virgin and contaminated (polluted) recycled aggregates. The aim of this research is the total replacement (100% coarse and fine) of natural aggregates (NA) by recycled concrete aggregates (RA) in the composition of a roller compacted concrete. The natural and recycled aggregates are characterised and compared. The mechanical properties and durability performances of concrete with contaminated RA are analysed. The experimental results showed that the polluted RA are much richer in chlorides than in sulphates and are leached if they are soaked in water. Significant differences were observed between the properties of original and new concrete and the results demonstrated the need of taking these contaminations into account.     

Antioxidant potential of rice bran extracts and its effects on stabilisation of cookies under ambient storage

Methanolic extracts of rice bran (MRB) were found to be the richest in phenolics than all the other extraction media, i.e. water, 80% methanol, 70% ethanol, diethyl ether. Thermal stability of MRB was determined by evaluating antioxidant activity of heated extracts in linoleic acid system. Cookies were prepared in sunflower oil premixed with MRB at different concentrations, i.e. 500, 1000 and 2000 ppm, and with butylated hydroxytoluene and α‐tocopherol at 200 ppm. Oxidative stability of cookies was measured by storing under ambient conditions for an year with periodical analysis after every 2 months. Fatty acid composition was determined by gas–liquid chromatography. A regular decrease in unsaturated fatty acids (USFA) and increase in saturated fatty acids was observed with the increase in storage period; all the stabilised samples showed appreciably less decrease in USFA than that of control sample. Induction period ranged from 14.73 to 31.22 h while control exhibited 7.5 h. Peroxide value, iodine value and free fatty acids were chosen as the parameters for quality evaluation of cookies. Results suggest rice bran to be a potential source of antioxidants for stabilisation of cookies.     

Modelling and performance comparison of optimal AIGaAs/GaAs DMTs and multichannel HEMTs for power amplification

We present two detailed studies concerning thedmt and the multichannelhemt for power amplifications. Each work comprises a first theoretical part where the structure is optimized by simulating the device. Technological realizations are hence performed at the laboratory. The following measurements give results very encouraging and permit to foresee the superior performance relatively to that of GaAs powermesfet.     

Formulation and characterisation of a self‐nanoemulsifying drug delivery system of amphotericin B for the treatment of leishmaniasis

This study was aimed to develop a self‐nanoemulsifying drug delivery system (SNEDDS) for amphotericin B (AmB) potential use in leishmaniasis through topical and oral routes. Two formulations, formulation A and formulation B (FA and FB) of AmB loaded SNEDDS were developed by mixing their excipients through vortex and sonication. The SNEDDS formulation FA and FB displayed a mean droplet size of 27.70 ± 0.5 and 30.17 ± 0.7 nm and zeta potential −11.4 ± 3.25 and −13.6 ± 2.75 mV, respectively. The mucus permeation study showed that formulation FA and FB diffused 1.45 and 1.37%, respectively in up to 8 mm of mucus. The cell permeation across Caco‐2 cells monolayer was 10 and 11%, respectively. Viability of Caco‐2 cells was 89% for FA and 86.9% for FB. The anti‐leishmanial activities of FA in terms of IC₅₀ were 0.017 µg/ml against promastigotes and 0.025 µg/ml against amastigotes, while IC₅₀ values of FB were 0.031 and 0.056 µg/ml, respectively. FA and FB killed macrophage harboured Leishmania parasites in a dose‐dependent manner and a concentration of 0.1 µg/ml killed 100% of the parasites. These formulations have the potential to provide a promising tool for AmB use through oral and topical routes in leishmaniasis therapy.Inspec keywords: nanomedicine, drops, microorganisms, electrokinetic effects, cellular biophysics, drug delivery systems, monolayers, drugs, diseasesOther keywords: self‐nanoemulsifying drug delivery system, topical routes, oral routes, SNEDDS formulation, mucus permeation study, cell permeation, leishmaniasis treatment, amphotericin B, zeta potential, Caco‐2 cell monolayer, vortex, sonication, droplet size, Caco‐2 cell viability, antileishmanial activity, promastigotes, amastigotes, Leishmania parasites     

Feasibility and performance evaluation of a 6LoWPAN‐enabled platform for ubiquitous healthcare monitoring

Technology has revolutionized medical practices by enabling more convenient and non‐intrusive monitoring of patient's health, leading to next generation ubiquitous healthcare (u‐healthcare). The exploitation of the Internet protocol version 6 addressing space along with the miniaturization of electronic devices has fostered providing interoperability and connectivity of wearable sensor devices in wireless body area networks to the Internet of Things. In this paper, we propose to integrate the IPv6 over low power wireless personal area network (6LoWPAN) to the u‐healthcare monitoring system architecture. The main objective is to study the feasibility of the 6LoWPAN‐enabled platform in real‐world scenarios dealing with medical data. The performance evaluation of this platform is carried out initially through simulations using OMNet++ and then supported by an experimental study using sensor motes and a customized micro‐computing unit. Performance metrics such as throughput, end‐to‐end delay, packet error rate, and energy consumption are investigated under acute health conditions, where patient's health information has to be sent continuously and at maximum rate to the care provider. The obtained results show that the proposed 6LoWPAN solution fulfills the main quality of service requirements of u‐healthcare applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Way forward in meeting energy challenges in Pakistan

In this review the energy potential of Pakistan from hydro, coal, wind, solar and nuclear sources has been discussed. The new projects that are being commissioned on coal, wind, solar, hydel and nuclear-based technologies have also been mentioned. The review has also explored the future prospects of the country’s energy requirements. Pakistan has potential to produce 100,000?MW of electricity from Thar coal for 20 years, 56,000?MW of hydroelectricity, 150,000?MW of wind energy and ～50,000?MW from solar sources. The coal-fired power generation is expected to 11,500?MW in period 2017–2019. The country is moving in the right direction to cater its energy needs. However, there is a need to find local and foreign investment in the country to meet high energy demands in the country in future.     

Ultrasonic synthesis of Zn-doped CdO nanostructures and their optoelectronic properties

The effect of Zn dopant on the growth of cadmium oxide (CdO) nanostructures through a sonochemical method was investigated. The X-ray diffraction (XRD) patterns of the nanoparticles show CdO cubic structures for the produced samples. Field emission scanning electron microscope (FESEM) images reveal that morphologies of the samples change, when they are doped with Zn atoms, and their sizes reduce. Room temperature photoluminescence (PL) and UV-Vis spectrometers were used to study optical properties of the samples. Evaluation of optical properties indicates that different emission bands result from different transitions and the value of CdO energy band gap increases due to doping. Studies of electrical properties of the nanostructures demonstrate that Zn dopant enhances electrical conductivity and photocurrent generation as the result of light illumination on the nanostructures due to improved density of photo-generated carriers. Considering the obtained outcomes, Zn dopant can alter the physical property of the CdO nanostructures.