Entity

Time filter

Source Type

Pearland, TX, United States

Dick R.,79 Group
Lighting Research and Technology | Year: 2014

Studies of our illuminated environment demonstrate the importance of light to humans, who by evolution are essentially daytime creatures. However, the study of behaviour and the biology that occurs during the night has clearly shown the importance of darkness for both humans and the ecological integrity of the countryside. Since humans are expanding their activity throughout the night and into rural areas, is there a compromise between the human desire for light and the need for darkness? All animals and plants have light thresholds to which they have evolved. We have applied the findings of scotobiology to determine outdoor lighting that minimizes the disruption of artificial light at night on the natural environment and on human health. It is not surprising that the key characteristics to be limited are the brightness, duration and extent of the emitted light, the amount of glare and the spectrum of the emitted light. To test the practicality of these limits, we present the patented design of a luminaire that bridges the desire for 24 × 7 human lifestyles and the protection of the nocturnal environment. © 2013 The Chartered Institution of Building Services Engineers. Source


Arulsamy A.D.,79 Group
Progress of Theoretical Physics | Year: 2011

A general quantum adiabatic theorem with and without the time-dependent orthogonalization is proven, which can be applied to understand the origin of activation energies in chemical reactions. Further proofs are also developed for the oscillating Schwinger Hamiltonian to establish the relationship between the internal (due to time-dependent eigenfunctions) and external (due to time-dependent Hamiltonian) timescales. We prove that this relationship needs to be taken as an independent condition for the quantum adiabatic approximation. We give four examples, including logical expositions based on the spin- 1/2 two-level system to address the gapped and gapless (due to energy level crossings) systems, as well as to understand how does this theorem allows one to study dynamical systems such as chemical reactions. Source


Karami A.,79 Group
Journal of the Iranian Chemical Society | Year: 2010

In this work the titanium dioxide powder was prepared by the optimized and simple Sol-Gel method and then characterized. The gelling pH was set to values of 3 (TiO2-A), 7 (TiO2-N) and 9 (TiO2-B) to observe the effect on the properties of the material. In these three cases nanoparticulated materials were obtained with particle sizes between 10nm and 20nm. The larger surface areas were obtained at pH 3, which is several times larger than the others. Furthermore, with the gelling condition pH 3, it was possible to synthesize pure anatase phase titania. Some preliminary results on the test of the photocatalytic activity of the synthesized materials in the reduction of nitric oxide are presented. Based on these results the nanoparticle TiO2, which was prepared in acidic pH 3 with the pure anatase phase and the lowest particle size has the highest reactivity for the photocatalytic reduction of nitric oxide. Source


Barker R.,University of Leeds | Neville A.,University of Leeds | Hu X.,79 Group | Cushnaghan S.,Royal Dutch Shell
Corrosion | Year: 2015

Over the last decade, significant advances in chemical inhibition have enabled operators to use carbon steel pipework in oil and gas facilities where sand production is a concern. The ability of these inhibitors to reduce both the electrochemical corrosion reactions and the mechanical damage attributed to particle impingement is well documented, but the underlying mechanisms have been the subject of less attention. This paper presents a review of three commercially available oilfield corrosion inhibitors (two standard corrosion inhibitors and one high shear-resistant inhibitor) in an effort to establish their performance in erosion-corrosion environments. Experiments were conducted at 45° C using a submerged impinging jet in carbon dioxide (CO2)-saturated conditions with a fluid velocity of 14 m/s and sand loading of 500 mg/L. A combination of gravimetric measurements, in situ electrochemistry, and surface profilometry allowed the inhibitors to be assessed based on a number of different parameters (i.e., mass loss, in situ corrosion behavior, and total penetration depth). The results demonstrate the importance of surface analysis techniques when evaluating the performance of inhibitors in erosioncorrosion environments, indicating that mass loss and in situ electrochemical techniques alone can sometimes provide misleading information in relation to their performance. The inhibitors are evaluated in erosion-corrosion environments where no semi-protective corrosion product formation occurs. Electrochemical impedance spectroscopy measurements are incorporated into the analysis to assist in interpreting inhibition mechanisms and to help determine how inhibitors may be capable of reducing both the erosion and corrosion components of material loss. © 2015, NACE International. Source


Hu X.,79 Group | Ismail I.M.,Weatherford | Neville A.,University of Leeds
NACE - International Corrosion Conference Series | Year: 2013

Sweet pitting corrosion related failures are a prime concern in oil and gas internal pipelines. Often, these types of failure have a great impact on the safety and environmental matters and can cause severe financial consequences to the operator. Chemical inhibitors have been used to provide effective protection for assets against both localized corrosion and general corrosion. In order to develop superior localized corrosion inhibitors, a better understanding of the mechanisms of the action and interaction of pitting and the film are required. An extensive study on the inhibition of pitting corrosion of carbon steel API 5L X65(1) in sweet conditions has been carried out. In this study, a laboratory methodology using in-situ monitoring and post-test surface analysis techniques has been developed to investigate pitting mechanisms due to localized breakdown of films formed in sweet environments. The effect of inhibitors on pitting growth has also been assessed. © 2013 by NACE International. Source

Discover hidden collaborations