Improved numerical methods for turbulent viscous flows aerothermal modeling program, phase 2

The details of a study to develop accurate and efficient numerical schemes to predict complex flows are described. In this program, several discretization schemes were evaluated using simple test cases. This assessment led to the selection of three schemes for an in-depth evaluation based on two-dimensional flows. The scheme with the superior overall performance was incorporated in a computer program for three-dimensional flows. To improve the computational efficiency, the selected discretization scheme was combined with a direct solution approach in which the fluid flow equations are solved simultaneously rather than sequentially

Bulk and contact-sensitized photocarrier generation in single layer TPD devices

In this paper, we report on the photoelectronic properties of TPD studied in sandwich geometry. In particular, we have obtained from both forward and reverse bias measurements the "mew-tau" product for holes in TPD. "mew" is the hole mobility and "tau" the carrier trapping time. The "mew-tau" product is a measure of the electronic quality of the material and allows a quantitative comparison of different samples. We have carried out numerical simulations to understand the photocurrent in these structures. We show that in reverse bias, the photocurrent (PC) is due to bulk. The carrier generation is governed by field assisted exciton dissociation at electric fields greater than 10^6 V/cm. At lower fields the generation of carriers occurs spontaneously in the bulk of the sample. In forward bias, the photocurrent is due to exciton dissociation at the ITO contact. We also obtain a "mew-tau" product for holes from forward bias PC measurements which is in agreement with the value obtained from reverse bias measurements. Based on our experiments, we demonstrate that TPD in a sandwich structure is a good candidate for cheap large area solar blind UV detector arrays.Comment: Submitted to J. Appl. Phy

Photoconduction in Alq3

Photoelectronic properties of Alq3 were studied by photoconductivity measurements in thin film, sandwich (ITO/Alq3/LiF/Al) devices. We find that the photocurrent is dominated by bulk generation of carriers for incident photon energies greater than 2.75 eV. The quantum efficiency of photocarrier generation has been measured from carrier collection measurements to be about 10%. The quantum efficiency is largely independent of electric field. This enables a direct measurement of the electric field dependence of mobility using photoconductivity measurements, which is used for quantitative analysis of the dark forward current in these devices. Photoconductivity measurements were also used to obtain (\mu_{0n} \tau_n) product which can be used as a measure of material quality. For Alq3, we find that the value of (\mu_{0n} \tau_n) product was between 3x10^{-15} cm^2/V to 8x10^{-15} cm^2/V for different samples. In forward bias, at high field the photocurrent shows saturation accompanied by a phase shift. These effects are attributed to space charge effects in the device.Comment: 12 figure

Transfer or Redemption for a Withdrawing Partner: An Indifference Econometric Decision Model Built on the Position Improvement Equilibrium ( PIE ) Concept

The preferred way for a withdrawing partner to leave a partnership is normally thought to be by way of redemption under Internal Revenue Code Section 736 rather than as a transfer under Section 741 The advantage to the continuing partnership lies in the deductability of the payment to the withdrawing partner for goodwill. The withdrawing partner benefits from a higher exchange price, increased by the tax benefits of redemption treatment. However, the following three factors tilt the preference back toward a 741 transfer for both parties: individual obligation of portions of the exchange price, with additional basis, goodwill negotiations and safeguarding of the optional basis adjustment. To allow for proper consideration of these factors, indifference equations are proposed which produce an exchange price that makes 741 as advantageous to the dominant party as 736. These equations constitute a dynamic interactive econometric model for finding a position improvement equilibrium ( PIE ) indifference model that provides an incisive decision tool. This model takes graduated tax brackets into consideration, heightening its value as a decision tool

Aerothermal modeling program, phase 2

The main objective of the NASA sponsored Aerothermal Modeling Program, Phase 2--Element A, is to develop an improved numerical scheme for predicting combustor flow fields. This effort consists of the following three technical tasks. Task 1 involves the selection and evaluation of various candidate numerical techniques. Task 2 involves an in-depth evaluation of the selected numerical schemes. Task 3 involves the convection-diffusion scheme and the direct solver that will be incorporated in the NASA 3-D elliptic code (COM3S)

Aerothermal modeling program. Phase 2, element A: Improved numerical methods for turbulent viscous recirculating flows

The objective of this effort is to develop improved numerical schemes for predicting combustor flow fields. Various candidate numerical schemes were evaluated, and promising schemes were selected for detailed assessment. The criteria for evaluation included accuracy, computational efficiency, stability, and ease of extension to multidimensions. The candidate schemes were assessed against a variety of simple one- and two-dimensional problems. These results led to the selection of the following schemes for further evaluation: flux spline schemes (linear and cubic) and controlled numerical diffusion with internal feedback (CONDIF). The incorporation of the flux spline scheme and direct solution strategy in a computer program for three-dimensional flows is in progress

Blue and white light electroluminescence in a multilayer OLED using a new aluminium complex

Synthesis, structure, optical absorption, emission and electroluminescence properties of a new blue emitting Al complex, namely, bis-(2-amino-8-hydroxyquinolinato), acetylacetonato Al(III) are reported. Multilayer OLED using the Al complex showed blue emission at 465 nm, maximum brightness of ~ 425 cd/m2 and maximum current efficiency of 0.16 cd/A. Another multilayer OLED using the Al complex doped with phosphorescent Ir complex showed 'white' light emission, CIE coordinate (0.41, 0.35), maximum brightness of ~ 970 cd/m2 and maximum current efficiency of 0.53 cd/A

Mucinous neoplasia of appendix: imaging and its relevance to management

Appendiceal mucocele is a rare pathology of the appendix that can present with non-specific symptoms. Therefore, imaging evaluation is essential for accurate diagnosis and proper management. To document importance of pre-operative imaging, we reviewed the scans, reports, and clinical data of nine patients with appendiceal mucocele who were treated at our institute. We also studied the literature on CT findings, histopathology, surgical management, prognosis, and recent guidelines for appendiceal mucocele. We suggest that pre-operative imaging can aid surgeons in selecting the most appropriate treatment plan for each patient, resulting in better outcomes. Certain critical imaging features, such as mural nodularity, irregular wall thickening, lymphadenopathy, cecal involvement, presence of free mucus, or pseudomyxoma peritonei, can alert surgeons to prepare for frozen section and an appropriate surgical approach. In conclusion, we recommend pre-operative imaging as a crucial tool for the diagnosis and management of appendiceal mucocele. Its use in identifying critical imaging features can help surgeons decide on the best surgical approach for each patient and ultimately lead to better outcomes