Optimal power management strategy for energy storage with stochastic loads

In this paper, a power management strategy (PMS) has been developed for the control of energy storage in a system subjected to loads of random duration. The PMS minimises the costs associated with the energy consumption of specific systems powered by a primary energy source and equipped with energy storage, under the assumption that the statistical distribution of load durations is known. By including the variability of the load in the cost function, it was possible to define the optimality criteria for the power flow of the storage. Numerical calculations have been performed obtaining the control strategies associated with the global minimum in energy costs, for a wide range of initial conditions of the system. The results of the calculations have been tested on a MATLAB/Simulink model of a rubber tyre gantry (RTG) crane equipped with a flywheel energy storage system (FESS) and subjected to a test cycle, which corresponds to the real operation of a crane in the Port of Felixstowe. The results of the model show increased energy savings and reduced peak power demand with respect to existing control strategies, indicating considerable potential savings for port operators in terms of energy and maintenance costs.

Reactive crisis management in construction projects

Patterns of communication and behaviour emerge within a construction project in response to a construction crisis. This paper investigates, within a grounded theory framework, the nature of these patterns, the sociological and psychological forces which shape them and their relationship with crisis management efficiency. A grounded theory is presented in four parts. The first part conceives a construction crisis as a period of social instability, arising from conflicting interest groups, seeking to exercise power in the pursuit of social structures which suit their political and economic interests. The second part sees a construction crisis as a de-sensitizing phenomenon which results in a period of behavioural instability and conflict which is self-perpetuating. The third part cites social structure as an important influence upon construction crisis management efficiency, in determining the efficiency of information flow, and the level of uncertainty between those affected. The fourth part points to the in-built defence mechanisms which construction crises have and to three managerial ironies which make construction crisis management difficult.

Optimal discrimination and classification of THz spectra in the wavelet domain

In rapid scan Fourier transform spectrometry, we show that the noise in the wavelet coefficients resulting from the filter bank decomposition of the complex insertion loss function is linearly related to the noise power in the sample interferogram by a noise amplification factor. By maximizing an objective function composed of the power of the wavelet coefficients divided by the noise amplification factor, optimal feature extraction in the wavelet domain is performed. The performance of a classifier based on the output of a filter bank is shown to be considerably better than that of an Euclidean distance classifier in the original spectral domain. An optimization procedure results in a further improvement of the wavelet classifier. The procedure is suitable for enhancing the contrast or classifying spectra acquired by either continuous wave or THz transient spectrometers as well as for increasing the dynamic range of THz imaging systems. (C) 2003 Optical Society of America.