General Electric (Qatar)

Preliminary results from an investigation on the application of dynamic power flow controllers to a stretch of the Qatar Transmission System (QTS) along the western coast of Qatar. The main objective of applying the power flow controller is to maintain balance of power flow between the networks or lines that supply to this weaker region of the QTS, and in turn support network security should the demand in this region grows. The paper will investigate the impact on steady-state power flow control using a Unified Power Flow Controller (UPFC), and the potential application of a Generalized Power Flow Controller (GUPFC), in the QTS to check if these controllers provide a viable solution looking into the future. In controlling of the power flow controller, this paper looks into the possibility of using phasor measurement units (PMUs) and synchrophasor based control. An assessment on the existing infrastructure of the QTS and necessary improvement needed to support implementation of the power flow controller and its control will be included in this paper along with a preliminary cost analysis. The modeling work and preliminary studies in this paper were conducted with PSS/E.

Solid solution hardening is sought and observed in two B2(cP2) CsCl and two C15(cF24) Cu2Mg type structures. New data are presented for the high-temperature compounds AlCo, AlRu, and Cr2Zr; prior data of Livingston on Cu2Mg are analyzed. From lattice parameters and specific gravities, cell occupancy numbers have been measured and used to infer likely defect types and concentrations. The effects of constitutional defects in binary compounds correlate with traditional substitutional solution hardening from elastic interactions due to size differences and modulus differences. The hardening from ternary solutes is similar in magnitude, but the defect structures are complicated and not yet adequately understood.

ABSTRACTThe growth of an epitaxial insulator such as CaF2. on Si substrates and ita subsequent overgrowth with epitaxial sen iconduct ors have a number of important applications in the electronics industry. In addition, it presents a unique opportunity to study an insulator/semiconductor interface under controlled conditions. We have studied the growth of epitaxial CaF. on Si substrates and their subsequent overgrowth with Si or Ge under various conditions. While epitaxial growth of CaF2, (which has an fee lattice structure as does Si) can be obtained on (100), (110) and (111) oriented Si substrates, the best quality crystal growth and surface morphology is obtained on (111) substrates as the CaF. (111) surface has the lowest free energy. Atomic steps on the original Si substrate surface are shown to have a detrimental effect on the epitaxial growth of CaF2. I-V measurements on the epitaxial (111) films show that the intrinsic breakdown field strength exceeds 2 MV/cm, however, high-field induced ionization can cause thermal breakdown at lower voltages. C-V measurements typically show ∼1012 states/cm in the Si band gap as grown. However, it is possible to reduce this number to less than 10 by annealing procedures after growth.

The refraction of acoustic duct waveguide modes emitted from the open end of a semi-infinite rectangular duct by a jet-like exhaust flow is studied theoretically. The problem is formulated as a Wiener-Hopf problem and is ultimately solved by an approximate method due to Carrier and Koiter. Continuity of transverse acoustic particle displacement and of acoustic pressure is assumed at the jet/still-air interface. The solution exhibits several features of the acoustics of moving media such as a source convection effect, zones of relative silence, simple refraction, etc. Plots of far-field directivity patterns are presented for several cases and show refraction effects to be important even at modest exhaust Mach numbers of order 0.3. Only subsonic exhaust Mach numbers are considered. In view of the problem’s technological interest, the solution for the far-field directivity is written out in full detail in the appendices. In the low-frequency limit when only one duct waveguide mode (the plane wave mode) propagates, we also examine the reflection coefficient. It is found that this reflection coefficient, in general, considerably exceeds either the no-flow value or the value for the case with uniform flow both inside and outside the waveguide (i.e., in the whole space). Apparently the acoustic medium mismatch enhances the geometric mismatch in the jet flow case, thus producing a higher reflection coefficient.

Film boiling heat-transfer coefficients, beyond “burnout,” of 800–2000 Btu/hr ft2 deg F, were measured with steam-water mixtures in annular flow at pressures of 800, 1100, and 1400 psi with healer temperatures not exceeding 1000 deg F. Variation of co-efficients with pressure, mass velocity, and steam quality are presented together with a correlation in the range of parameters studied.

The effect of warm prestressing at various stress levels on the notch bend fracture properties of a Ni-Mo-V steel at two levels of strength and Charpy FATT is determined. Warm prestressing of a notch sensitive steel effected increases in notch fracture strengths up to 150 percent of the unprestressed value. The fracture strength after prestressing increases proportionately with prestress level. The results indicate that the efficacy of warm prestressing is dependent on the temperature at which the notch strength is determined and its relation to the notch strength versus temperature behavior for a material.

Some observations showing the adverse effects of certain kinds of nonmetallic inclusions on the strength and fracture behavior of alloy steel test specimens are presented. The observations pertain to the effects in tests at low and high temperatures and under steady and cyclic loading.

Abstract In this paper the authors discuss the steam turbine wheel fracture which occurred at Tanners Creek early in 1953. The major parts of the investigation which was made to determine the cause of this fracture are presented together with the general conclusions.