System for 3-D Real-Time Tracking of MRI-Compatible Devices by Image Processing

Real-time processing of MRIs is reported as a method of 3D tracking of mechanical devices within the field of view using passive microcoil fiducials. The specific implementation described makes use of two scan planes for full 3D tracking of a 5-DOF manipulator arm used for prostate biopsy under image guidance. Real-time tracking was observed with a maximum update rate of 0.42 frames per second for a maximum probe velocity of 10 mm/s. The localization of fiducials had a mean error of 0.36 (plusmn0.17) mm (p < 0.02), leading to a mean error in the needle tip position of 2.6 (plusmn0.3) mm (p < 0.05).     

Adaptive Feedback Synchronization of a General Complex Dynamical Network With Delayed Nodes

In the past decade, complex networks have attracted much attention from various fields of sciences and engineering. Synchronization is a typical collective behavior of complex networks that has been extensively investigated in recent years. To reveal the dynamical mechanism of synchronization in complex networks with time delays, a general complex dynamical network with delayed nodes is further studied. Based on a suitable model, we investigate the adaptive feedback synchronization and obtain several novel criteria for globally exponentially asymptotic synchronization. In particular, our hypotheses and the proposed adaptive controllers for network synchronization are very simple and can be readily applied in practical applications. Finally, numerical simulations are provided to illustrate the effectiveness of the proposed synchronization criteria.     

Offline signature verification with generated training samples

It is often difficult to obtain sufficient signature samples to train up a signature verification system. An elastic matching method to generate additional samples is proposed to expand the limited training set so that a better estimate of the statistical variations can be obtained. The method differs from existing ones in that it is more suitable for the generation of signature samples. Besides this, a set of peripheral features, which is useful in describing both the internal and external structures of signatures, is employed to represent the signatures in the verification process. Results showed that the additional samples generated by the proposed method could reduce the error rate from 15.6% to 11.4%. It also outperformed another existing method which estimates the class covariance matrix through optimisation techniques. Results also demonstrated that the peripheral features are useful for signature verification.     

Physical properties of isobutylene based block copolymers

Physical, mechanical and thermal properties of a new class of isobutylene based model block copolymers are studied and contrasted with those of traditional thermoplastic elastomers based on polydienes and saturated polydienes (polyolefins) such as Kraton (or Vector) and Kraton G block copolymers. Melt state rheological and dynamic mechanical measurements confirm that thermodynamic interactions between polystyrene (S) and polyisobutylene (iB) or poly‐p‐tert‐butylstyrene (tbS) and iB are comparable to, if not larger than, those between S and polybutadiene (B) or S and ethylene/butene‐1 copolymer (EB). Physical properties for the S‐iB‐S and tbS‐iB‐tbS block copolymers, particularly the injection‐moldability and cut‐growth characteristics, are found to be considerably different from those found for the S‐B‐S and S‐EB‐S systems. We attribute this behavior to the longer entanglement chain length of iB compared with those for B and EB.     

Property rights implications of publicprivate joint ventures: a comment

Wong, K. C. and Walker, A. (2000) Construction Management and Economics, 18 (2), 131-138 have argued that co-operative joint venture arrangements (with state enterprises in the People's Republic of China) reduce the dissipation of rent under public ownership, which leads to an apparent transfer of shares from the public institution to the private developer. This proposition is challenged, and it is demonstrated using economic analysis that co-operative joint ventures between Hong Kong and China are a feasible option for developers and public institutions.