the narrow operating window between pore pressure and fracture pressure makes drilling difficult in some operations. a feasibility study of managed pressure drilling (mpd) is carried out on iran darquain oil field. the previous wells drilled in this field showed that mud returns were lost during drilling gadvan formation. the present work addresses this problem by means of surface back pressure...

Drilling and blasting have numerous applications in the civil and mining engineering. Due to the two major components of rock masses, namely the intact rock matrix and the discontinuities, their behavior is a complicated process to be analyzed. The purpose of this work is to investigate the effects of the geomechanical and geometrical parameters of rock and discontinuities on the rock mass blas...

The present study was conducted to investigate current density of0.3 0.7 Al Ga N/ GaN multiple quantum well solar cell (MQWSC) under hydrostaticpressure. The effects of hydrostatic pressure were taken into account to measureparameters of 0.3 0.7 Al Ga N/ GaN MQWSC, such as interband transition energy, electronholewave functions, absorption coefficient, and dielectric con...

the present study investigates the performance and relative accuracy of four lattice-hole theory based equations of state in modeling and correlating the liquid density of pure refrigerants. following the gathering of a database of 5740 experimental liquid density datapoints of 36 pure refrigerants belonging to five different categories including cfcs, hcfcs, pfcs, hfcs and hfes, ranging from 6...

The present study investigates the performance and relative accuracy of four lattice-hole theory based equations of state in modeling and correlating the liquid density of pure refrigerants. Following the gathering of a database of 5740 experimental liquid density datapoints of 36 pure refrigerants belonging to five different categories including CFCs, HCFCs, PFCs, HFCs and HFEs, ranging from 6...

Estimating the costs of blasting operations is an important parameter in open-pit mining. Blasting and rock fragmentation depend on two groups of variables. The first group consists of mass properties, which are uncontrollable, and the second one is the drill-and-blast design parameters, which can be controlled and optimized. The design parameters include burden, spacing, hole length, hole diam...

The low-temperature conductivity of low-density, high-mobility, two-dimensional hole systems in GaAs was studied. We explicitly show that the metal-insulator transition, observed in these systems, is characterized by a well-defined critical density, p0 c . We also observe that the low-temperature conductivity of these systems depends linearly on the hole density, over a wide density range. The ...

We construct a generalized gradient approximation ~GGA! for the density nxc(r,r1u) at position r1u of the exchange-correlation hole surrounding an electron at r, or more precisely for its system and spherical average ^nxc(u)&5(4p) *dV u N *dr n(r)nxc(r,r1u). Starting from the second-order density gradient expansion, which involves the local spin densities n↑(r),n↓(r) and their gradients 1n↑(r),...