Development of heat flux sensors in turbine airfoils

The objective is to develop heat flux sensors suitable for use on turbine airfoils and to verify the operation of the heat flux measurement techniques through laboratory experiments. The requirements for a program to investigate the measurement of heat flux on airfoils in areas of strong non-one-dimensional flow were also identified

Advanced high temperature heat flux sensors

To fully characterize advanced high temperature heat flux sensors, calibration and testing is required at full engine temperature. This required the development of unique high temperature heat flux test facilities. These facilities were developed, are in place, and are being used for advanced heat flux sensor development

Turbine blade and vane heat flux sensor development, phase 2

The development of heat flux sensors for gas turbine blades and vanes and the demonstration of heat transfer measurement methods are reported. The performance of the heat flux sensors was evaluated in a cylinder in cross flow experiment and compared with two other heat flux measurement methods, the slug calorimeter and a dynamic method based on fluctuating gas and surface temperature. Two cylinders, each instrumented with an embedded thermocouple sensor, a Gardon gauge, and a slug calorimeter, were fabricated. Each sensor type was calibrated using a quartz lamp bank facility. The instrumented cylinders were then tested in an atmospheric pressure combustor rig at conditions up to gas stream temperatures of 1700K and velocities to Mach 0.74. The test data are compared to other measurements and analytical prediction

Image-charge induced localization of molecular orbitals at metal-molecule interfaces: Self-consistent GW calculations

Quasiparticle (QP) wave functions, also known as Dyson orbitals, extend the concept of single-particle states to interacting electron systems. Here we employ many-body perturbation theory in the GW approximation to calculate the QP wave functions for a semi-empirical model describing a $\pi$-conjugated molecular wire in contact with a metal surface. We find that image charge effects pull the frontier molecular orbitals toward the metal surface while orbitals with higher or lower energy are pushed away. This affects both the size of the energetic image charge shifts and the coupling of the individual orbitals to the metal substrate. Full diagonalization of the QP equation and, to some extent, self-consistency in the GW self-energy, is important to describe the effect which is not captured by standard density functional theory or Hartree-Fock. These results should be important for the understanding and theoretical modeling of electron transport across metal-molecule interfaces.Comment: 7 pages, 6 figure

The Civil War and Reconstruction in Mississippi County: The Story of Sans Souci Plantation

“The Civil War and Reconstruction in Mississippi County: The Story of Sans Souci Plantation” examines Sans Souci plantation in northeast Arkansas and the McGavock-Grider family who lived there as a microcosm of the establishment of other plantations in the Arkansas delta. From the settlement of the plantation in the 1830s to the end of Reconstruction, Sans Souci closely resembles what life was like for other planters and their families in what was then the frontier. John Harding McGavock and his wife Georgia saw their planter status rise throughout the 1850s, but as the Civil War came to Mississippi County, the family faced turmoil and loss. Despite the hardships brought by war, the family was able to rebound during Reconstruction, as they retained over 3,000 acres of prime delta land, continuing their prominent position in the county. Their story is one small piece of Mississippi County’s Civil War and Reconstruction history, but it is nonetheless important to putting together a more complete picture of what life was like for Arkansans in the delta in the 19th century

Development of heat flux sensors for turbine airfoils

The objectives of this program are to develop heat flux sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat flux sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal cycle and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat flux measurements produced by these sensors. The results of the cylinder in cross flow tests are given

Interpretation of x-ray-absorption dichroism experiments

A rule is derived to use x-ray magnetic circular dichroism spectra to extract the magnetic moment of the conduction-band states with j= l -1/2 separately from those with j= l + 1/2 as a function of energy. This quantity is straightforward to determine from the electronic band structure. The rule is illustrated with an application to pure iron and to the random substitutional alloy Fe_{80}CO_{20}

Cross‐border acquisitions by sovereign wealth funds: A legitimacy‐based view

Research SummaryDrawing on institutional economics and the legitimacy-based view of political risk, we investigate the factors determining the realization of cross-border investments by sovereign wealth funds (SWFs), whose investments often suffer from a lack of legitimacy in host countries. Using matching models on all the realized and potential investments, we find that investments are more likely to materialize when the SWF home country and the host country enjoy cordial political relations or are involved in a trade agreement. Contrary to the theoretical predictions, SWF politicization does not per se represent an impediment to the realization of investments. Rather, it has a negative effect on the likelihood of an investment's realization only in the presence of trade agreements.Managerial SummaryA recent trend in the global economy is the increasing cross-border investment activity undertaken by sovereign wealth funds (SWFs), large investment vehicles where financial and political goals often co-exist. On the grounds of possible financial or political destabilization, SWFs' cross-border investments attract scrutiny and suspicion in host countries, hindering their realization. We analyze SWF- and country-level factors that may determine the successful realization of SWFs' cross-border acquisitions. We suggest that managers ex ante select target firms and host countries by considering their fund's governance and degree of independence from home-country politics in interaction with bilateral (home-host country) political and economic relations, so as to secure legitimacy for their investments and maximize the chances that cross-border investment strategies may materialize