Evolutionary hybrid approaches for generation scheduling in power systems

Generation scheduling (GS) in power systems is a tough optimisation problem which continues to present a challenge for efficient solution techniques. The solution is to define on/off decisions and generation levels for each electricity generator of a power system for each scheduling interval. The solution procedure requires simultaneous consideration of binary decision and continuous variables. In recent years researchers have focused much attention on developing new hybrid approaches using evolutionary and traditional exact methods for this type of mixed-integer problems. This paper investigates how the optimum or near optimum solution for the GS problem may be quickly identified. A design is proposed which uses a variety of metaheuristic, heuristics and mathematical programming techniques within a hybrid framework. The results obtained for two case studies are promising and show that the hybrid approach offers an effective alternative for solving the GS problems within a realistic timeframe.     

Aryl-aryl bond formation by the fluoride-free cross-coupling of aryldisiloxanes with aryl bromides

The prevalence of the biaryl structural motif in biologically interesting and synthetically important molecules has inspired considerable interest in the development of methods for aryl-aryl bond formation. Herein we describe a novel strategy for this process involving the fluoride-free, palladium-catalysed cross-coupling of readily accessible aryldisiloxanes and aryl bromides. Using a statistical-based optimisation process, preparatively useful reaction conditions were formulated to allow the cross-coupling of a wide range of different substrates. This methodology represents an attractive, cost-efficient, flexible and robust alternative to the traditional transition-metal-catalysed routes typically used to generate molecules containing the privileged biaryl scaffold.     

Novel and efficient copper-catalysed synthesis of nitrogen-linked medium-ring biaryls

Herein, a new copper-catalysed strategy for the synthesis of rare nitrogen-linked seven-, eight- and nine-membered biaryl ring systems is described. It is proposed that the reaction proceeds through a highly activated intramolecularly co-ordinated copper catalyst. The process is technically simple, proceeds under relatively mild conditions, displays a broad substrate scope and forms biologically valuable products that are difficult to synthesise by other methods. We envisage that this methodology will prove useful in a wide synthetic context, with possible applications in both target-oriented and diversity-oriented synthesis.     

PNA to DNA to microarray decoding facilitates ligand discovery

The development of a method for the amplification of PNA tags (Svensen et al., in this issue of Chemistry & Biology) should expand the range of biological targets amenable to screening using PNA-encoded combinatorial libraries and thus facilitate the discovery of new biologically useful agents.     

Comparison of luminescence lifetimes in quartz following alpha and beta irradiation

The change in optically stimulated luminescence sensitivity of quartz associated with annealing is accompanied by a change in luminescence lifetime, whereas, in contrast, the change in sensitivity associated with irradiation by alpha particles rather than by beta particles is not accompanied by any change in luminescence lifetime. This is compatible with the usual ‘saturation’ explanation for the significantly lower luminescence sensitivity of quartz to alpha irradiation compared to the luminescence sensitivity to beta irradiation.     

Recent developments in underwater imaging using the ultrasonic image converter tube

The Sokolov ultrasonic image converter provides a simple real time imaging system capable of good resolution and range in turbid water conditions. The tube is operated with anode potential target stabilisation and capacitive signal collection. Spurious signals at the ultrasound frequency are generated because of the stray capacitance of the scanned quartz surface. These signals are separated by modulating the electron beam at a different frequency and employing a head amplifier tuned to the intermediate frequency. Displayed images are free from fringes due to spurious signals and are unaffected by Doppler frequency shift. Factors which affect the resolution of an ultrasonic visualisation system are discussed.