asphaltenes are the n-pentane or n-heptane insoluble fractions of crude oil that remain in solution under reservoir temperature and pressure conditions. they are destabilized and start to precipitate when the pressure, temperature and/or composition changes occur during primary production. the precipitated asphaltene particles will then grow in size and may start to deposit onto the production ...

This paper presents a comprehensive explanation of the formation of the electric arc between opening contacts in a current carrying electric circuit. As the contacts begin to open a molten metal bridge forms between them. The rupture of this bridge and the initial formation of the electric arc are studied in both atmospheric air and vacuum using experiments to determine the direction of metal t...

Selenium in ambient conditions exhibits two crystalline allotropic forms. The thermodynamically stable phase is the pseudo-1D trigonal form with ${}^{1}{/}_{\ensuremath{\infty}}$[Se] chains. A metastable composed of $[{\mathrm{Se}}_{8}]$ rings also coexists. Both are studied herein by means density functional theory. recent SCAN offers a fair description both phases. Birch-Murnaghan equation st...

Wetting front instability creates a shallow induction zone from which fingers emerge that rapidly transport water and solutes downwards. How the induction zone affects finger location and spacing is unknown. In the moist subsoil, fingers may well dissipate because the finger tips no longer have to overcome the water entry value. Both flow regions were investigated in a two-dimensional chamber w...

The possibility of obtaining solid ingots (without gas porosity in the volume) from high-nitrogen steel Fe-Cr-Mo-N-C system by method self-propagating high-temperature synthesis under nitrogen pressure is shown present paper. It has been established that with an increase mass fraction carbon 0.09 % to 0.30 as-cast metal, hardness metal increases. At same time, structural-phase composition consi...

Two-phase heat transfer is experimentally examined through vertical small diameter tubes, D =1.45 and 2.8 mm using water under a pressure of 50 to 81 kPa and a natural circulation condition. The pool boiling correlation by Stephan-Abdelsalam and the thermosyphon boiling correlation by Imura, et al. predict the measured experimental data in the 2.8 mm tube with an error of -30%. A large heat tra...

The application of traditional well test interpretation methods cannot comprehensively consider characteristics stress sensitivity and non-Darcy flow for low-permeability composite gas reservoirs, which makes it difficult to obtain real reservoir parameters. Based on the micro-mechanism analysis in motion equation was improved. Thus, a mathematical model established belongs inclined with conven...

This paper provides the evidence of a sweet spot on the boot/foot as well as the method for detecting it with a wearable pressure sensitive device. This study confirmed the hypothesized existence of sweet and dead spots on a soccer boot or foot when kicking a ball. For a stationary curved kick, kicking the ball at the sweet spot maximized the probability of scoring a goal (58-86%), whereas havi...

The pumping of water from a sand box with a finer layer on the top was studied theoretically and experimentally. The sand box, saturated at its lower portion and initially in hydrostatic equilibrium, was pumped at constant rate. The results show that significant negative air pressure can be generated in the vadose zone during pumping. The negative air pressure increases quickly in the earlier s...