Phase separation and morphology in polymer modified colloids

The morphology of films of sterically stabilised polystyrene particles, PS, with added free poly(vinyl alcohol), PVA, and poly(vinyl pyrrolidone), PVP, was investigated with scanning electron microscopy and correlated to the phase behaviour and interactions. In the case of the PS/PVP system exhibiting depletion phase separation, large polymer domains (ca. 7 μm) were present in the solid state when free polymer concentration exceeded ca. 13%. This concentration was well within the two-phase region of the phase diagram. Similar polymer domains were also observed for the homogeneous system PS/PVA. The surface of the films was sealed at free polymer concentrations of ca. 20% and ca. 40% for PVP/PS and PVA/PS, respectively. The final film morphology reflects non-equilibrium conditions arising from the increase in system viscosity due to particle close packing and continuous phase thickening by the free polymer. In the case of PS/PVP systems, incomplete depletion phase separation and phase demixing and prevention of particle restabilisation gives rise to large free polymer domains in the final film. Bridging flocculation was argued to be responsible for the large polymer domains, some with internal structure, observed with the PVA/PS systems.     

Biclustering in data mining

Biclustering consists in simultaneous partitioning of the set of samples and the set of their attributes (features) into subsets (classes). Samples and features classified together are supposed to have a high relevance to each other. In this paper we review the most widely used and successful biclustering techniques and their related applications. This survey is written from a theoretical viewpoint emphasizing mathematical concepts that can be met in existing biclustering techniques.     

Hydraulic fracture closure in a pressure-sensitive elastoplastic medium

This paper examines fracture closure in a Mohr-Coulomb pressure-sensitive dilatant material. The analysis is based on fracture propagation and closure of a plane strain geometry using a fully coupled elastoplastic hydraulic fracturing model. It is shown that the closure pattern of a fracture which has first been propagated is completely different from the closure pattern of a pressurized stationary fracture. A pressurized stationary elastoplastic fracture closes uniformly but remains open after the applied load is released. An elastoplastic fracture which has first been propagated, makes surface contact initially near the fracture tip and subsequently towards the mouth of the fracture. Applications of fracture closure pattern can be found in different aspects of hydraulic fracturing such as in the insitu parameters determination from the inversion of the pressure vs time record and in the closure stress on propped fractures.     

PRO-MOTION: Support for mobile database access

In order to provide data consistency in the presence of failures and concurrency, database methods will continue to be important to the processing of shared information in a mobile computing environment. It is important, therefore, that we develop transaction processing systems that accommodate the limitations of mobile computing, such as frequent disconnection, limited battery life, low-bandwidth communication and reduced storage capacity, so that we can migrate existing database applications to mobile environments. In this paper, motivated by these needs, we propose a mobile transaction processing system that supports disconnected transaction processing in a mobile client-server environment. The proposed system employs compacts, which encapsulate access methods, state information and consistency constraints, to allow for local management of database transactions on mobile computers.     

Multimedia Execution Hardware Accelerator

In this paper we show that some expressions frequently used in multimedia applications can be formulated as a general add-multiply-add operation. We further show a hardwired implementation of the Add-Multiply-Add instruction which is no more complex than the multiplier implementation. Furthermore we show that two frequently motion estimation operations, the Sum and Mean of Absolute Differences, can be implemented in hardware requiring also approximately the same cycle time as the multiplication. We also show that our approach can be extended easily to provide the computation of the Sum and Mean of Absolute Difference of a 16×16 pixel block in no more than four machine cycles. Additionally we propose a codec hardwired mechanism for the Paeth predictor used in the Portable Network Standard (PNG) that requires at most two general purpose ALU cycles. We extend the paeth unit to include the median, maximum and minimum operations on three inputs with no additional cycle time and we also extend the Add-Multiply-Add unit to include the mean of three numbers. Finally we propose a multimedia hardware accelerator to accommodate all the proposed operations. The proposed unit is an extension of the multiply pipeline with ALU extensions with no extra stages added. The unit operates on 32 instructions in total.     

Model-based control of temperature and energy requirements in a fluidised furnace reactor

The main objective is to improve the control performance during catalyst processing experiments in a furnace heated fluidised bed reactor. A model-based predictive control strategy is implemented for the tight control of the reactor temperature and the overall energy requirements. A detailed dynamic model is developed for the furnace reactor and validated using open-loop experimental data. Dynamic programming techniques are used for the calculation of the optimal sequence of manipulated variables that minimise the difference between the desired and the predicted reactor temperature trajectories. The model predictive control strategy leads to superior performance than the previously installed system that consisted of conventional PID controllers.     

Representation of Crack-Tip Plasticity in Pressure Sensitive Geomaterials: Large Scale Yielding

We model large scale Mohr-Coulomb yielding that accompany fractures in weak rocks, by means of dislocations. The basic equations are derived from a simple model of the crack tip plasticity which represents the plasticity by superdislocations placed at the effective centres of the crack tip process zone.