Abstract Plant turnarounds are one of the most critical events in Saudi Arabian oil and gas industries. Shutdowns have potential to affect plant’s cash flow objectives either a constructive nor bad way. A heat exchanger is an essential equipment for some procedures refineries plant it will decide shutdown span. In exchanger, welded tube tubesheet joint basic factor which requires different qual...

A novel active region design is proposed to achieve long-wavelength ( = 1550-nm) diode lasers based on a type-II quantum-well (QW) design of (In)GaAsN–GaAsSb grown on a GaAs substrate. The strain-compensated structures hold potential as an ideal active region for 1500-nm GaAs-based vertical cavity surface emitting lasers. A design analysis and optimization of 1550-nm emitting structures is pres...

Interwell optical-phonon-assisted transitions are studied in an asymmetric double-quantum-well heterostructure comprising one narrow and one wide coupled quantum wells (QW’s). We show that the depopulation rate of the lower subband states in the narrow QW can be significantly enhanced, thus facilitating the intersubband inverse population, if the depopulated subband is aligned with the second s...

We consider the effect of different unitary noise mechanisms on the evolution of a quantum walk (QW) on a linear chain with a generic coin operation: (i) bit-flip channel noise, restricted to the coin subspace of the QW, and (ii) topological noise caused by randomly broken links in the linear chain. Similarities and differences in the respective decoherent dynamics of the walker as a function o...

We present theoretical results of the calculations optical functions for Cu$_2$O quantum well (QW) with Rydberg excitons in an external homogeneous electric field arbitrary strength. Two configurations perpendicular and parallel to QW planes are considered energetic region discrete excitonic states continuum states. With help real density matrix approach, which enables derivation analytical exp...

We present a novel analysis for correcting the measured differential carrier lifetime to account for carrier population in both the barrier and separate confinement heterostructure (SCH) regions of quantum-well (QW) lasers. This analysis uses information obtained from the measured spontaneous emission spectra to correct the measured lifetime and obtain the intrinsic well lifetime. Once the intr...

The term sorption is generally used to describe the initial penetration and the dispersal of the permeant molecules into food matrices (Chirife and Iglesias 1978) and, more generally, into all kinds of polymers (Naylor 1989; Tsujita 1992). This term includes adsorption, absorption into microvoids, and cluster formation. When a food matrix is placed in a humid atmosphere, the relationship betwee...

The effect of electrostatic shielding of the polarization fields in nanostructures at high carrier densities is studied. A simplified analytical model, employing screened, exponentially decaying polarization potentials, localized at the edges of a QW, is introduced for the ES-shielded quantum confined Stark effect (QCSE). Wave function trapping within the Debye-length edge-potential causes blue...

Optical properties and carrier dynamics in type-II Ga(As)Sb/GaAs quantum dots (QDs) embedded in an InGaAs quantum well (QW) are reported. A large blueshift of the photoluminescence (PL) peak is observed with increased excitation densities. This blueshift is due to the Coulomb interaction between physically separated electrons and holes characteristic of the type-II band alignment, along with a ...

Optical and structural characterizations were conducted on an InGaAsN quantum well (QW) with large energy bandgap barrier material consisting of InGaAsP (Eg 1⁄4 1:62 eV) grown by metalorganic chemical vapor deposition. A growth pause annealing technique substantially improves both the structural and the optical quality of the QW. With an optimum growth pause of 14 s, surface roughness reduces b...