A New Two-Parameter Family of Potentials with a Tunable Ground State

In a previous paper we solved a countably infinite family of one-dimensional Schr\"odinger equations by showing that they were supersymmetric partner potentials of the standard quantum harmonic oscillator. In this work we extend these results to find the complete set of real partner potentials of the harmonic oscillator, showing that these depend upon two continuous parameters. Their spectra are identical to that of the harmonic oscillator, except that the ground state energy becomes a tunable parameter. We finally use these potentials to analyse the physical problem of Bose-Einstein condensation in an atomic gas trapped in a dimple potential.Comment: 15 pages, 5 figure

A Physics-Based Heterojunction Bipolar Transistor Model for Integrated Circuit Simulation

The purpose of this research effort was to derive a physics-based dc model for a Heterojunction Bipolar Transistor HBT. The dc model was then linearized to arrive at a small-signal model that accurately predicts the devices electrical behavior at microwave frequencies. This new model offers features not found in previous analytical or physics-based HBT models such as consideration of a cylindrical emitter-base geometry and is direct implementation into SPICE Simulation Program with Integrated Circuit Emphasis. The device model parameters were determined from a knowledge of the device material, geometry, and fabrication process. The model was then developed by using semiconductor physics to calculate modified parameters for the existing SPICE bipolar junction transistor BJT model

Electrical Activation Studies of Ion Implanted Gallium Nitride

A comprehensive and systematic electrical activation study of Si-implanted GaN was performed as a function of ion implantation dose, anneal temperature, and implantation temperature. Additionally, Mg-implanted GaN was also investigated. Temperature-dependent Hall effect measurements and photoluminescence (PL) spectra were used to characterize the samples. GaN wafers capped with AlN were implanted with Si ions at doses ranging from 1x1013 to 5x1015 cm-2 and annealed from 1050 to 1350 °C. The optimum anneal temperature for samples implanted with the higher Si doses is around 1350 °C, exhibiting nearly 100% electrical activation efficiency. Exceptional mobilities and carrier concentrations were obtained on all Si-implanted samples. PL spectra revealed nearly complete implantation damage recovery as well as the nature of the yellow luminescence plaguing nearly all Si-doped GaN. Additionally, GaN wafers were implanted with Mg and various coimplants and annealed from 1100 to 1350 °C. All of the Mg-implanted and most of the Mg-coimplanted GaN samples became extremely resistive, and did not show definite p-type conductivity even after annealing at 1350 °C, remaining highly resistive even at a sample temperature as high as 800 K. A dominant 2.36 eV green luminescence band observed in the PL spectra of all Mg-implanted samples is attributed to a Mg-related deep complex DAP transition. The inefficient electrical activation of Mg acceptors implanted into GaN is attributed to these Mg-related deep complexes

Culture as a component of complexity in construction

W112 Culture in Construction: Paper ID: 798Both culture and construction have been suggested to be complex – culture as relating to, even governing, human behaviour and construction as a context in which human activities occur in the design, production, occupation, and use and disposal of major artefacts: buildings and infrastructure. Indeed, construction has been subject to various definitions and categorisations of complexity to assist analysis of the processes employed in the realisation and use of its outputs; including consideration of managerial and technical complexity. Historically, intuitive understanding of what constitute complex construction projects was supplemented with naïve objective measurements – such as the proportionate cost of building services. However, such approaches have failed to be very helpful in gaining understanding of the relationships between inputs to the realisations, the transformations within the processes and the resultant performance outputs. Following on from chaos theory, the emerging field of complexity theory, with its emphasis on linkages within systems and the ‘softer’ elements, has significant potential for providing insights. Hence, this paper examines culture in the context of and application to construction organisations and projects using the perspectives of complexity theory towards helping to determine a more detailed research agenda in the hope of gaining significantly greater understanding through this paradigm.postprintThe 2010 World Congress of CIB on Building a Better World, University of Salford, Salford, U.K., 10-14 May 2010. In Proceedings: TG59 and W112 - Special Track 18th CIB World Building Congress, 2010, p. 192-20

Unbinding of giant vortices in states of competing order

Funding: EPSRC (UK) via Grants No. EP/I031014/1 and No. EP/H049584/1.We consider a two-dimensional system with two order parameters, one with O(2) symmetry and one with O(M), near a point in parameter space where they couple to become a single O(2+M) order. While the O(2) sector supports vortex excitations, these vortices must somehow disappear as the high symmetry point is approached. We develop a variational argument which shows that the size of the vortex cores diverges as 1/root Delta and the Berezinskii-Kosterlitz-Thouless transition temperature of the O(2) order vanishes as 1/1n(1/Delta), where Delta denotes the distance from the high-symmetry point. Our physical picture is confirmed by a renormalization group analysis which gives further logarithmic corrections, and demonstrates full symmetry restoration within the cores.Publisher PDFPeer reviewe

Conflict on multi-national construction projects

By definition, multi-national construction projects bring together organisations and individuals from different countries and, therefore, almost inevitably, different cultures. As cultures underpin behaviour and behaviour has major impacts on performance - both what is desired and what is realised - issues of cultural compatibility between project participants are important. A further aspect relates to attitudes to conflict and thence disputes regarding their likelihood, causes and consequences - in essence, how they may be managed. This paper aims to critically review the theory and literature regarding cultures and to examine their relevance to selection of multi-national project participants, management of conflict and resulting outcomes for project performance and participant satisfaction. Of particular note are aspects of cultural compatibility/cultural distance for both selection of project participants and resultant performance.published_or_final_versio

Trust and money: 20 years of (no) progress?

General Paper Session W55 - Economics of the built environment: Tracking no. 248 Tracking Number 248In almost 20 Years since Latham published the interim report ‘Trust and Money’ in which he asserted that there was too little of either in the UK construction industry, has anything changed? This paper addresses issues of what trust is, how it is created and its fragility, and progresses to examine how trust operates in the construction industry. The second major thread, money, is examined in the context of the economics and financing of construction projects and organisations in an era in which globalisation of the finance industry has occurred as well as global and local crises in that industry and many countries economies. Market emphases and process changes have occurred at several levels, continuing existing trends but also spawning new ones. A key question, which is examined as the underpinning, central theme of this paper, is that although structural changes and procedural changes are highly evident, what has changed in behaviour within the industry, why, and with what consequences regarding trust and money?postprintThe International Conference on Management and Innovation for a sustainable built environment (MISBE 2011), Amsterdam, The Netherlands, 20-23 June 2011. In Proceedings of MISBE, 2011, p. 1-1