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Certain Drawbacks (certain + drawback)
Selected AbstractsImproved adaptive control for the discrete-time parametric-strict-feedback formINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 12 2009Graciela Adriana González Abstract Adaptive control design for a class of single-input single-output nonlinear discrete-time systems in parametric-strict-feedback form is re-visited. No growth restrictions are assumed on the nonlinearities. The control objective is to achieve tracking of a reference signal. As usual, the algorithm derives from the combination of a control law and a parameter estimator (certainty equivalence principle). The parameter estimator strongly lies on the regressor subspace identification by means of an orthogonalization process. Certain drawbacks of previous schemes are analyzed. Several modifications on them are considered to improve the algorithm complexity, control performance and numerical stability. As a result, an alternative control scheme is proposed. When applied to the proposed class of systems, global boundedness and convergence remain as achieved objectives while improving the performance issues of previous schemes. Copyright © 2009 John Wiley & Sons, Ltd. [source] An enhanced explicit rate algorithm for ABR traffic control in ATM networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2001Y. H. Long Abstract A high performance, low computational complexity rate-based flow control algorithm which can avoid congestion and achieve fairness is important to ATM available bit rate service. The explicit rate allocation algorithm proposed by Kalampoukas et al. is designed to achieve max,min fairness in ATM networks. It has several attractive features, such as a fixed computational complexity of O(1) and the guaranteed convergence to max,min fairness. In this paper, certain drawbacks of the algorithm, such as the severe overload of an outgoing link during transient period and the non-conforming use of the current cell rate field in a resource management cell, have been identified and analysed; a new algorithm which overcomes these drawbacks is proposed. The proposed algorithm simplifies the rate computation as well. Compared with Kalampoukas's algorithm, it has better performance in terms of congestion avoidance and smoothness of rate allocation. Copyright © 2001 John Wiley & Sons, Ltd. [source] Gene stacking in transgenic plants , the challenge for 21st century plant biotechnologyPLANT BIOTECHNOLOGY JOURNAL, Issue 2 2005Claire Halpin Summary One of the major technical hurdles impeding the advance of plant genetic engineering and biotechnology is the fact that the expression or manipulation of multiple genes in plants is still difficult to achieve. Although a small proportion of commercial genetically modified (GM) crops present ,stacked' or ,pyramided' traits, only a handful of products have been developed by introducing three or more novel genes. On the research front, a variety of conventional and more novel methods have been employed to introduce multiple genes into plants, but all techniques suffer from certain drawbacks. In this review, the potential and problems of these various techniques and strategies are discussed, and the prospects for improving these technologies in the future are presented. [source] Development of efficient and durable sources of white lightCOLORATION TECHNOLOGY, Issue 1 2010Timothy L Dawson This review presents a brief history of the development of light sources over the centuries to provide one of the human race's basic needs , light. Recent moves in Europe to encourage the adoption of compact fluorescent lamps as more energy-efficient replacements for incandescent lights, despite certain drawbacks, are described. Rapid strides are now being made in the development of solid-state ,white' lights which are already sufficiently durable and efficient to warrant adoption for both domestic and public lighting purposes. Their basic construction and comparative performance, properties and uses are fully described, together with the many ideas for improving their brightness and durability still further. Solid-state devices offer additional savings compared with those which should be achieved under the EU's targeted replacement of incandescent lights by 2012, and later one can expect such devices to compete with high-pressure sodium luminaires for street lighting. [source] | ||||||||||