Enhancing design learning using a digital repository

The process of design is context dependent and open-ended, and therefore does not revolve around a specific body of information or knowledge. The educational paradigm shift in the area of engineering design from teaching to coaching and the increased use of social constructivist learning ideals requires students to have access to as wide a range of information as possible. Digital resources provide an excellent opportunity for extending the range of information available to design students and to this end, as part of a joint research program with Stanford University, the University of Strathclyde has developed a groupware product called LauLima to provide students with a collaborative environment which allows them to gather, organise, store and share information. This paper describes the improvement to design learning, based on a Design Knowledge Framework, in a 3rd year product design engineering project from session 03/04 to 04/05 which has been facilitated by the implementation of this technology

Journeys to Open Educational Practice: UKOER/SCORE Review Final Report

In 2008 the JISC Good Intentions report concluded that the landscape around learning materials had changed sufficiently to support a range of sustainable models for sharing. The report charted and acknowledged the long history of approaches to support sharing that had helped to shape the landscape. Most of the models highlight a growing acknowledgement of the need to build and support open and sustainable communities to share practice and resources. Indeed such communities are often the key to sustaining the service, whichever model is adopted. This is the type of model most likely to encourage sharing between teachers as well as learners. The growing OER community is taking collaborative approaches to tackling the ongoing challenges of raising awareness, licensing and trust issues, and standards and technologies. The challenge for the UK now is to ensure that our HE institutions are enabled to create policies, practices and support their staff to accelerate the transformations required to contribute and benefit from this global movement. It is also vital to ensure that we capture the real picture of use and re-use of such services and collections to inform future OER programmes. HEFCE funding for OER initiatives followed this report in 2009 and has, in many ways, provided some of the scaffolding and support for a variety of individuals, communities and institutions to move forwards in their own journeys, whether they started years before in other contexts or had just joined on the road to open sharing

Comparing and calibrating black hole mass estimators for distant active galactic nuclei

Black hole mass is a fundamental property of active galactic nuclei (AGNs). In the distant universe, black hole mass is commonly estimated using the MgII, Hbeta, or Halpha emission line widths and the optical/UV continuum or line luminosities, as proxies for the characteristic velocity and size of the broad-line region. Although they all have a common calibration in the local universe, a number of different recipes are currently used in the literature. It is important to verify the relative accuracy and consistency of the recipes, as systematic changes could mimic evolutionary trends when comparing various samples. At z=0.36, all three lines can be observed at optical wavelengths, providing a unique opportunity to compare different empirical recipes. We use spectra from the Keck Telescope and the Sloan Digital Sky Survey to compare black hole mass estimators for a sample of nineteen AGNs at this redshift. We compare popular recipes available from the literature, finding that mass estimates can differ up to 0.38+-0.05 dex in the mean (or 0.13+-0.05 dex, if the same virial coefficient is adopted). Finally, we provide a set of 30 internally self consistent recipes for determining black hole mass from a variety of observables. The intrinsic scatter between cross-calibrated recipes is in the range 0.1-0.3 dex. This should be considered as a lower limit to the uncertainty of the black hole mass estimators.Comment: ApJ in press, 11 pages, 10 figure

Fermi-level position at a semiconductor-metal interface

We have investigated the phenomenon of Fermi-level pinning by charged defects at the semiconductor-metal interface. Two limiting cases were investigated. In the first case we modeled an infinitely thick metallic coverage. In the second case we modeled a submonolayer coverage by using a free semiconductor surface containing defects. In both cases we assumed that most of the defect-induced interface states are localized inside the semiconductor, not more than a few angstroms away from the metal. Under these conditions we have estimated the difference in Fermi-level position between n- and p-type semiconductors to be less than 0.05 eV in the case of a thick metallic coverage. This difference was shown to be the maximum possible one, and it occurs only when there is no pinning. When there is pinning, this difference is even smaller. No such upper bound on the difference in Fermi-level position exists in the case of submonolayer coverage. We have also found that the defect density required to pin the Fermi level is ∼10^14 cm^-2 in the case of a thick metallic coverage, but only ∼10^12 cm^-2 in the case of a submonolayer coverage

Near-band‐gap photoluminescence of Hg_(1−x)Cd_xTe

The results of photoluminescence studies of Hg_(1−x)Cd_xTe with x=0.32 and 0.48 for temperatures between 5 and 30 K are described. In the x=0.32 and x=0.48 material, band‐to‐band, band‐to‐acceptor, and donor‐to‐acceptor luminescencelines are observed. We report the first observation of bound‐exciton luminescence in HgCdTe, which we observe in the samples with x=0.48

Direct interelectrode tunneling in GaSe

Using thin films of the layer compound gallium selenide, we have fabricated experimental structures which are nearly ideal for the study of tunneling currents. All of the parameters relevant to current flow in these structures can be independently determined since single-crystal gallium selenide films have the properties of the bulk material and also well-defined interfaces. A new analytical technique for determining the energy-momentum dispersion relation within the forbidden gap of a solid is discussed and applied to current-voltage data obtained from metal-GaSe-metal structures. The resulting E-k relation is shown to be an intrinsic property of GaSe. Tunneling currents in GaSe are shown to be quantitatively understood in terms of this E-k relation, the geometry of a given structure, and a simple model of current flow via tunneling

Optical Reflection Studies of Damage in Ion Implanted Silicon

Optical (3–6.5 eV) reflection spectra are presented for crystalline Si implanted at room temperature with 40 keV Sb ions to doses of less than 2×10^15/cm^2. These spectra, and their deviation from the reflection spectrum of crystalline Si, are discussed in terms of a model based on the average dielectric properties of the implanted region. For samples having a high ion dose (>10^15/cm^2) the observed spectra resemble the spectra of sputtered Si films. Anneal characteristics of the reflection spectra are found to be dose dependent. These observations are compared to, and found to substantiate, the results of other experimental techniques for studying lattice damage in Si

Contact-limited currents in metal-insulator-metal structures

The physical mechanisms underlying current flow in solid-state MIM structures are reviewed with emphasis on criteria for determining the dominant conduction mechanism in a given experimental situation. Measurements of the bias and temperature dependence of currents through structures incorporating a thin film of single-crystal gallium selenide are reported, and are shown to be in excellent agreement with the predictions of a simple physical model of contact-limited emission. Independently measured properties of bulk single-crystal gallium selenide are used in all calculations; no adjustable parameters are employed. We believe that this study presents unequivocal evidence for contact-limited thermionic currents in solid-state MIM structures