The change from steerable motor to rotary steerable system has been both technically and commercially successful in Lybia. Through these case histories the paper will demonstrate benefits resulting from the use of rotary steerable systems that have led to a step change in overall drilling performance in the Middle East. This paper describes the successful introduction and application of a rotar...

To understand the function of neuro-active molecules, it is necessary to know how far they can diffuse in the brain. Experimental measurements show that substances confined to the extracellular space diffuse more slowly than in free solution. The diffusion coefficients in the two situations are commonly related by a tortuosity factor, which represents the increase in path length in a porous med...

an efficient procedure is presented for the evaluation of solid oxide fuel cell (sofc) anode microstructure triple phase boundary length (tpbl). triple phase boundary- the one that is common between three phases of the microstructure- has a great influence on the overall efficiency of sofc because all electrochemical reactions of anode take place in its vicinity. therefore, evaluation of tpbl f...

The phenomenological permeation coefficients were determined for two artificial cellulose membranes of known thickness and water content. Transport of non-electrolytes was studied with tagged water, urea, glucose, and sucrose. The effect of the unstirred layers on the experimental determination of the coefficients is discussed. Frictional coefficients between membrane matrix and solutes, and be...

Many diseases affect blood vessel morphology. This report analyzes vessel attributes (tortuosity, vessel density, radius, and terminal branch count) within 5 malignant gliomas as seen by high-resolution MR. Results are compared to those in the same anatomical region of 14 normal controls. All tumor patients had marked increases in vessel tortuosity and terminal branch count. These results raise...

By means of transillumination (microtransilluminator and light pipe), comparative analyses were carried out on geometry, topography, and morphometry of microcirculation in the cerebral cortex, left atrial muscle, and mesentery of the cat using computer analysis. In addition, specific types of capillary distribution (concurrent, countercurrent, and asymmetric distribution) in these three organs ...

Pore structure, tortuosity and permeability are considered key properties of porous materials such as cement pastes to understand their long-term durability performance. Three-dimensional image analysis techniques were used in this study to quantify pore size, effective porosity, tortuosity, and permeability from the X-ray computed tomography (CT) images of deteriorated pastes that were subject...

PURPOSE To report a case of familial retinal arteriolar tortuosity with acute hippocampal infarction. METHOD Single-patient case report. RESULTS A 50-year-old woman presented with blurred vision and was found to have cataract, retinal hemorrhages, and tortuous retinal arterioles in both eyes. Similar findings of tortuous retinal arterioles were observed in her daughter and son. In her past ...

Tortuosity (T) is a parameter describing an average elongation of fluid streamlines in a porous medium as compared to free flow. In this paper several methods of calculating this quantity from lengths of individual streamlines are compared and their weak and strong features are discussed. An alternative method is proposed, which enables one to calculate T directly from the fluid velocity field,...