Small-signal power transient modelling and regulation in Raman amplified optical fibre links

A Raman amplifier is a type of optical amplifier that finds application in long-haul wavelength division multiplexed optical communications systems. Despite the potentially complicated nonlinear and distributed nature of the optical power dynamics that can arise in Raman amplified optical fibre links, it is shown that a number of simple modelling approaches point towards the applicability of low-order models that can satisfactorily capture the small-signal dynamics of such links in the neighbourhood of fixed set-points. Based on this observation, a simple modelling and linear control design procedure is presented with the objective of synthesising finite-dimensional feedback controllers that can achieve small-signal power transient regulation across a range of optical signal wavelengths. The application of this procedure is shown to yield satisfactory closed-loop performance and robustness in a specific simulation example.     

Radioimmunoassay for measurement of bovine alpha-lactalbumin in serum, milk and tissue culture media

A sensitive, specific radioimmunoassay for bovine alpha-lactalbumin (alpha-la) suitable for measurement of serum, tissue culture media and milk was developed. alpha-La was not detected in serum from prepubertal male or female cattle, but was detected as early as 60 d of gestation in nulliparous Holstein heifers, the level being greatly increased during the last one third of gestation. Serum from cross bred beef heifers contained less alpha-la and it was not detected until late gestation. Concentrations of alpha-la in serum samples from pregnant multiparous Holstein cows decreased at drying-off and subsequently increased just before parturition. Secretion of alpha-la by mammary tissue explants from steroid-primed prepubertal Holstein heifers was induced by the addition of bovine prolactin, ovine prolactin or human growth hormone to tissue culture media.     

Metaphor and psychology: A reply to Gholson and Barker.

Suggests, in reply to the analysis of B. Gholson and P. Barker (see PA, 73:10704), that they may have overlooked a single construct (the underlying metaphor of the psyche) that embodies incommensurable, although not necessarily competing, theories that may distinguish evolution in psychology from that of other sciences. It is contended that while technology, methodology, novelty, and empirical results are factors in the evolution of psychology, the evolution can be measured by changes in metaphor. (6 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

2008半导体库存仍然居高不下

据iSuppli公司报告,2008年第一季度多数厂商在季中降低或者缩窄了营业收入预期,与当时相比,第二财季的情况比较正面.在第二财季季中展望中,多数厂商重申了季度营业收入预期或者只是略微收紧了预估区间.     

Impact of computers on professional practice: A survey of current practices and attitudes.

Surveyed 227 practicing psychologists to explore the impact of computers on the everyday practice of psychology and practitioners' attitudes toward specific uses of computers. Whereas more than half of the respondents reported using computers in their practices, most restricted their use to clerical applications. Few practitioners used their computer for more clinical applications. Reasons most frequently reported for not using computers related to lacking the necessary skills and experience and to financial considerations. Overall, practitioners had positive attitudes toward a variety of specific applications of computers. Implications of these findings for facilitating the appropriate use of computers by practitioners are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photoluminescence of copper ion exchange BK7 glass planar waveguides

Copper–alkali ion exchange technology was used to prepare BK7 glass planar waveguides. The photoluminescence spectra of the waveguides were studied with fluorescence spectrophotometer. It was observed that there were strong emission peaks at around 520 nm, which were strongly influenced by the ion-exchange times. Besides the time, the ion-exchange temperature was important factor as well, the higher ion-exchange temperature was found to bring a blue shift of emission spectra. The blue–green emission band originates from different transition mechanism of energy level. The spectroscopy features of copper within the glass host were also affected by the excitation wavelength, which resulted in a shift of the emission band peaks.     

WireWarping: A fast surface flattening approach with length-preserved feature curves

This paper presents a novel approach — WireWarping for computing a flattened planar piece with length-preserved feature curves from a 3D piecewise linear surface patch. The property of length-preservation on feature curves is very important to industrial applications for controlling the shape and dimension of products fabricated from planar pieces. WireWarping simulates warping a given 3D surface patch onto plane with the feature curves as tendon wires to preserve the length of their edges. During warping, the surface-angle variations between edges on wires are minimized so that the shape of a planar piece is similar to its corresponding 3D patch. Two schemes — the progressive warping and the global warping schemes are developed, where the progressive scheme is flexible for local shape control and the global scheme gives good performance on highly distorted patches. Experimental results show that WireWarping can successfully flatten surface patches into planar pieces while preserving the length of edges on feature curves.     

Combined FRM and GDFT filter bank designs for improved nonuniform DSA channelisation

Multistandard channelisation for base stations is a big application of generalised discrete Fourier transform modulated filter banks (GDFT‐FBs) in digital communications. For technologies such as software‐defined radio and cognitive radio, nonuniform channelisers must be used if frequency bands are shared by different standards. However, GDFT‐FB‐based nonuniform channelisers can suffer from high filter orders when applied to wideband input signals. In this paper, various combinations of GDFT‐FB with the frequency response masking technique are proposed and evaluated for both uniform and nonuniform channelisation applications. Results show that the proposed techniques achieve savings in both the number of filter coefficients and the number of operations per input sample. Copyright © 2015 John Wiley & Sons, Ltd.