Desynchronization of Large Scale Delayed Neural Networks

We consider a ring of identical neurons with delayed nearest neighborhood inhibitory interaction. Under general conditions, such a network has a slowly oscillatory synchronous periodic solution which is completely characterized by a scalar delay di erential equation with negative feedback. Despite the fact that the slowly oscillatory periodic solution of the scalar equation is stable, we show that the associated synchronous solution is unstable if the size of the network is large

β-nucleated isotactic polypropylene with different thermomechanical histories investigated by synchrotron X-ray

Isotactic polypropylene (iPP), as one of the most versatile commodity thermoplastic polymers, is a polymorphic material having several crystal modifications, among which the β-form exhibits higher performance including excellent impact strength and improved elongation at break.Up to now, the effective and convenient way to prepare the iPP with high content of β-phase has been successfully achieved by addition of certain β-nucleating agent. Since the coexistence of β-nucleating agent and flow (shear flow, extensional flow or mixed), which usually exists in common industrial processing, makes the crystallization process more complex, their combined effect on the structure evolution of polymers, especially in the early stage of crystallization is still not well understood. The mechanical properties of iPP depend strongly on its crystallinity, crystal orientation and morphology determined by the conditions during preparation. On the other hand, the mechanical properties of polymers can also be modulated by deformation processing, which is directly related to the deformation-induced structure transition. However, the transition mechanism of different crystal forms and structure-property correlation still remain unclear. In this thesis, time-resolved synchrotron X-ray scattering was firstly used for the in-situ study of the structural and morphological developments of β-nucleated iPP during shear-induced crystallization. It was found that the crystallization process was strongly influenced by the concentration of β-nucleating agent, shear rate and shear temperature. Then extension-induced crystallization was investigated by a novel melt draw experiment, where a different crystallization mechanism compared to the shear-induced crystallization was found. Subsequently, β-nucleated iPP samples with different thermomechanical histories were scanned by synchrotron X-ray microbeam to construct their overall morphological distributions, including distributions of crystallinity, lamellar thickness, orientation, etc. Finally, these morphology-identified samples were investigated by in-situ synchrotron X-ray measurements coupled with mechanical testing to follow the structure evolution during deformation at elevated temperature. It was found that the deformation behaviour of β-nucleated iPP was closely associated with its initial morphology, its subsequent variation during stretching as well as the stretching conditions including the stretching rate and stretching temperature. The current study would not only contribute to the development of crystallization and deformation theory but also be beneficial for the material design

Proposing a Revised Pedestrian Walkway Level of Service Based on Characteristics of Pedestrian Interactive Behaviours in China

The objective of this study is to analyse characteristics of Pedestrian Interactive Behaviours (PIBs) in order to propose a revised pedestrian walkway Level of Service (LOS) in China. Field data on overtaking and evasive behaviours were collected at a metro station walkway in Shanghai, China to calculate macro and micro indicators. Occurrence intensities of these two PIBs initially increased with moderate density and later decreased with high density that reduced available space. PIBs were also analysed in terms of sideways behaviours to account for the varying difficulties of PIBs at different densities. It was found that available space for PIBs was the main factor contributing to the intensity features. Moreover, the different space demands of the two PIBs resulted in different features between them. Finally, a revised pedestrian walkway LOS was proposed based on the macro and micro characteristics of PIBs in China.</p

Development of Fuzzy Logic Forecast Models for Location-Based Parking Finding Services

Park-and-ride (PnR) facilities provided by Australian transport authorities have been an effective way to encourage car drivers to use public transport such as trains and buses. However, as populations grow and vehicle running costs increase, the demand for more parking spaces has escalated. Often, PnR facilities are filled to capacity by early morning and commuters resort to parking illegally in streets surrounding stations. This paper reports on the development of a location-based parking finding service for PnR users. Based on their current location, the system can inform users which is the best station to park their cars during peak period. Two criteria—parking availability and the shortest travel time—were used to evaluate the best station. Fuzzy logic forecast models were used to estimate the uncertainty of parking availability during the peak parking demand period. A prototype using these methods has been developed based on a case study of the Oats Street and Carlisle PnR facilities in Perth, Western Australia. The system has proved to be efficacious and has the potential to be applied to other parking systems