Analysis and synthesis of resistive n-port networks

Various aspects of analysis and synthesis of resistive n-port networks are considered in this paper. Two different characterizations of the network are examined, the Y matrix characterization and the K matrix characterization. Based on these characterizations, a set of equations is derived which relate the edge admittances with the elements of these matrices. When the K matrix is given, these equations are linear and can be solved analytically. When the Y matrix is given, the equations are bilinear and cannot be solved analytically. In this case, the problem is formulated as an optimization problem and techniques of nonlinear programming are used to obtain a realization. Synthesis from the Y matrix is finally extended to include sensitivity considerations.     

Analysis of a varnish applied by Nicéphore Niépce to make a print used for photographic purpose transparent

Nicéphore Niépce carried out a lot of meticulous experiments that led him to the invention of photography. In particular, in the 1820s, he obtained heliographs by coating a substrate with a light-sensitive substance, which was then exposed to light under a paper print made translucent with the help of varnish. The objective of the work described here is to determine how Niépce made these paper prints transparent. Did he use his experimental knowledge on photosensitive resins, or did he apply commonly used recipes of his time to make paper transparent? To date, no studies have been carried out on the varnish used by Nicéphore Niépce and no previous research has undertaken analytical investigations on Nicéphore's prints, using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Gas Chromatography/Mass Spectrometry (GC/MS). In this paper, we identify the varnishes used by Nicéphore Niépce on four transparent prints, now belonging to the Nicéphore Niépce museum in Chalon-sur-Saône, France. The varnish he used was based on a diterpenic Pinaceae sp. resin (most probably colophony). The finding is supported by historical knowledge about varnishes.     

LEDs as a tool to enhance faded colours of museums artefacts

A procedure to enhance the faded colours of museums artefacts is presented. The method is based on adjusting the spectral profile of the light while maintaining a given white colour of the illumination. The procedure is tested using colour LED clusters and a series of damaged samples and their good condition counterparts. The intensity of the three components of four feasible LED clusters is computed in order to produce white illumination metameric to a white LED light source taken as a reference. Colorimetric calculations are performed to model the colour changes undergone by target colour samples using illumination based on colour LED association with respect to the white LED reference. The model is based on CIELAB specification and allows to optimize the choice of three-colour LED associations that modify the hue and the saturation of a few target colour areas of illuminated samples while other areas are left moderately desaturated. Modelling and experimental visual validation were practically obtained by adjusting the intensity of five calibrated colour LEDs, blue, cyan, green, amber and red, accommodated in a light booth. A visual validation was conducted asking 20 observers to rate the colourfulness appearance of aged inkjet prints under every LED cluster with respect to the colourfulness of their original counterparts under the reference white LED source. The visual assessments agreed with the colorimetric predictions. Finally, a demonstration is shown of the feasibility of the method by simulating the rejuvenated appearance of a natural history specimen of which the museum possesses two differently aged items.     

Human postdiscrimination gradients: The effects of three-stimulus discrimination training

Young adult subjects were trained in a discrimination involving three pure tones varying in pitch, with two positive stimuli and a negative stimulus located midway between the two. Subjects in the control conditions were trained only with the two positive stimuli. Generalization gradients were bimodal in all cases, but for the control subjects, the modes were at the positive stimulus values, while postdiscrimination gradients were displaced away from the negative stimulus toward the extremes of the continuum. Since, with this procedure, the training and test adaptation levels were the same, the observed displacements are difficult to explain in terms of an adaptation-level account of peak shifts. The observed shifts are more consistent with the conditioning-extinction model which assumes interactions between inhibitory and excitatory gradients. However, overall response rates did not reflect the action of summation processes.     

Intellectual Property Rights in Computer Education: Legal,Societal, and Ethical Issues

Intellectual property rights related to computer usage in academia require precise definition. The Office of Technological Assessment has made great strides in this direction. States, universities, and professional organizations have dealt with the inherent complexities of the problem. Legal cases have tested current laws. Attorneys have made clear distinctions between copyrights and patents related to intellectual property rights. Both EDU‐COM and ADAPSO have addressed societal and ethical issues in written documents. Business, industry, and professional organizations have been concerned, but society and especially educators must also address intellectual property rights. Copyright laws related to electronic media must be honored. Computer ethics and computer law should be included in current computer science courses. Academia has the responsibility to educate all those on campus as to appropriate ethical and legal behavior with respect to these issues. Academia cannot hide or ignore these problems.     

Developing University Teachers: an account of a scheme designed for postgraduate researchers on a lecturing career path

Abstract

There is a growing recognition within higher education institutions of the importance of teaching as a core activity for trainee academics. This paper outlines and reports on a scheme which has been established to address the needs of postgraduate researchers who wish to build a career as university teachers. The scheme, now under review at the close of its first year of operation, is one which provides a potential model for other institutions. The paper includes extracts from a frank discussion involving participants in the scheme and highlights some of the practical difficulties which have occurred, in addition to the many benefits which are both expected in the future as well as some which are currently accruing