Computer program to predict noise of general aviation aircraft: User's guide

Program NOISE predicts General Aviation Aircraft far-field noise levels at FAA FAR Part 36 certification conditions. It will also predict near-field and cabin noise levels for turboprop aircraft and static engine component far-field noise levels

Competitive or cooperative relationships in clusters: a comparative study of two internationalising agro-processing clusters in Ghana

An efficient policy supporting clustered business operations necessitates an appreciation of the dynamics of rivalry and collaborations among businesses. This paper postulates that variation in competition and cooperation can significantly influence the nature of business relationships among clustered businesses, which is essential for cluster policy particularly (Newland, 2003) as most research on rivalry and cooperation in clusters have been in developed economies. This paper seeks to fill this gap in the literature in African clusters based on original empirical research. The study adopts a mixed method research design allowing for data triangulation to study two food processing clusters. The approach comprises a survey and in-depth interview with key actors along the supply chain. The findings show that business clusters with more formal business structures tend to have minimal horizontal competition but higher vertical cooperation. Comparatively, clusters with more socially embedded milieu tend to have higher levels of cooperation and minimal competition in both vertical and horizontal relationships. The research also shows that such variations in inter-business relationships have an effect on cluster operations in terms of business access to finance, formal contract, sharing of innovation and the way they relate to different stakeholders in their supply chain. This paper advances a critical case for international business theory on clusters in Africa to incorporate the distinctive business relationships in SME clusters. It also demonstrates how unique location-specific attributes of developing economies hold the key to sustaining the operations of SME-based clusters

A study of the effectiveness of a phonetic and activity approach to the teaching of spelling in grade four,

Includes appendices. Thesis (M.A.)--Boston Universit

Coherence of Spin Qubits in Silicon

Given the effectiveness of semiconductor devices for classical computation one is naturally led to consider semiconductor systems for solid state quantum information processing. Semiconductors are particularly suitable where local control of electric fields and charge transport are required. Conventional semiconductor electronics is built upon these capabilities and has demonstrated scaling to large complicated arrays of interconnected devices. However, the requirements for a quantum computer are very different from those for classical computation, and it is not immediately obvious how best to build one in a semiconductor. One possible approach is to use spins as qubits: of nuclei, of electrons, or both in combination. Long qubit coherence times are a prerequisite for quantum computing, and in this paper we will discuss measurements of spin coherence in silicon. The results are encouraging - both electrons bound to donors and the donor nuclei exhibit low decoherence under the right circumstances. Doped silicon thus appears to pass the first test on the road to a quantum computer.Comment: Submitted to J Cond Matter on Nov 15th, 200

High Fidelity Single Qubit Operations using Pulsed EPR

Systematic errors in spin rotation operations using simple RF pulses place severe limitations on the usefulness of the pulsed magnetic resonance methods in quantum computing applications. In particular, the fidelity of quantum logic operations performed on electron spin qubits falls well below the threshold for the application of quantum algorithms. Using three independent techniques, we demonstrate the use of composite pulses to improve this fidelity by several orders of magnitude. The observed high-fidelity operations are limited by pulse phase errors, but nevertheless fall within the limits required for the application of quantum error correction.Comment: 4 pages, 3 figures To appear in Phys. Rev. Let

Electron Paramagnetic Resonance of Boron Acceptors in Isotopically Purified Silicon

The electron paramagnetic resonance (EPR) linewidths of B acceptors in Si are found to reduce dramatically in isotopically purified 28Si single crystals. Moreover, extremely narrow substructures in the EPR spectra are visible corresponding to either an enhancement or a reduction of the absorbed microwave on resonance. The origin of the substructures is attributed to a combination of simultaneous double excitation and spin relaxation in the four level spin system of the acceptors. A spin population model is developed which qualitatively describes the experimental results.Comment: 4 pages, 3 figure