Towards an understanding of hole superconductivity

From the very beginning K. Alex M\"uller emphasized that the materials he and George Bednorz discovered in 1986 were $hole$ superconductors. Here I would like to share with him and others what I believe to be $the$ key reason for why high $T_c$ cuprates as well as all other superconductors are hole superconductors, which I only came to understand a few months ago. This paper is dedicated to Alex M\"uller on the occasion of his 90th birthday.Comment: Dedicated to Alex M\"uller on the Occasion of his 90th Birthday. arXiv admin note: text overlap with arXiv:1703.0977

A Way to the Dark Side of the Universe through Extra Dimensions

As indicated by Einstein's general relativity, matter and geometry are two faces of a single nature. In our point of view, extra dimensions, as a member of the {\em geometry face}, will be treated as a part of the {\em matter face} when they are beyond our poor vision, thereby providing dark energy sources effectively. The geometrical structure and the evolution pattern of extra dimensions therefore may play an important role in cosmology. Various possible impacts of extra dimensions on cosmology are investigated. In one way, the evolution of homogeneous extra dimensions may contribute to dark energy, driving the accelerating expansion of the universe. In the other way, both the energy perturbations in the ordinary three-space, combined with homogeneous extra dimensions, and the inhomogeneities in the extra space may contribute to dark matter. In this paper we wish to sketch the basic idea and show how extra dimensions may lead to the dark side of our universe.Comment: 10 pages, 3 figures. To appear in the proceedings of 2002 International Symposium on Cosmology and Particle Astrophysics (NTU, Taipei, Taiwan), May 31 - June 2, 200

THEORETICAL IMPLICATIONS OF STRESS AND MAGNETIC-FIELD SPLITTING OF GR1-LINE IN DIAMOND

The g-value of the excited state associated with the GR1 line is analysed in terms of the Coulson-Kearsley defect-molecule model (1957) for the vacancy in diamond. It is shown that the experimentally observed g value is entirely consistent with the expected 1T2 level of the model provided quenching by the dynamic Jahn-Teller effect is considered. This quenching is estimated from stress splitting data for the GR1 line. The result supports strongly the view that the GR1 centre is the neutral vacancy

Development of an undergraduate multidisciplinary engineering project

During their time at university it is necessary for undergraduate engineering students to develop not just technical skills related to their chosen engineering subject, but to also develop team working, time management, self organisation and decision making skills that will enable them to work effectively as engineers in the real world after graduation. These important transferable skills are highly sought after by industry and any chance to identify where such skills have been successfully used during an undergraduate degree course is a valuable addition to a student’s CV when subsequently entering the job market. To address the need of developing transferable skills, the School of Engineering and Design Multidisciplinary Project (MDP) was introduced in 2007 to provide first year undergraduate students with an opportunity to work together in multidisciplinary teams on a design and construction project. Each team is comprised of students from across the range of subject areas within the School and tasked with designing and building a robotic vehicle to tackle an obstacle course. The basis for the kits provided to each team are Lego Mindstorms robots for a majority of groups while the remaining groups are provided with a Parallax Basic STAMP 2 chip and a micro-controller chip to design their vehicle around. Figure 1 shows a selection of the 50 completed project builds from the 2009 MDP, showing the wide array of designs produced by the students. This paper describes the main aims of the MDP and gives an overview of how it has developed over the last three years to become a key part of the engineering undergraduate programme at Brunel University

The effect of correlation between demands on hierarchical forecasting

The forecasting needs for inventory control purposes are hierarchical. For SKUs in a product family or a SKU stored across different depot locations, forecasts can be made from the individual series’ history or derived top-down. Many discussions have been found in the literature, but it is not clear under what conditions one approach is better than the other. Correlation between demands has been identified as a very important factor to affect the performance of the two approaches, but there has been much confusion on whether positive or negative correlation. This paper summarises the conflicting discussions in the literature, argues that it is negative correlation that benefits the top-down or grouping approach, and quantifies the effect of correlation through simulation experiments