Scheduling tirage champagne production

Linear programming models for the scheduling of tirage champagne production are presented. The basic model demonstrates that cyclic schedules which reduce the average holdings of both maturation and finished product stock can be determined. Reduced costs associated with tirage bottle rewashing indicate that this is not an economic strategy. A common maturation stock model is presented as an option for future potential earnings

Scheduling in the manufacture of evaporative air conditioners

The MISG examined the problem of scheduling production of air conditioners at Seeley International. Seeley's objective was to meet their demand in a more cost-effective way. Two models are proposed to achieve this objective. A long term master production schedule with a yearly planning horizon was formulated to give Seeley a broad based schedule for planning production to meet forecast demands and production constraints. Output from this model is designed to provide the appropriate number of units of each product type or sub-assembly item to be produced in the following week. This output is then designed to be the input to a more detailed short term model for scheduling production at the machine level. The short term model is formulated to handle a mixture of both finished products and sub-assemblies. The objective of the short term model is to minimise total production time to free up the use of resources in order to allow for external orders. Directions for further work are discussed

The application of cellular automata to weather radar

A possible cellular automaton approach to weather (and in particular rainfall) modelling is considered. After posing a paradigm problem in a manner reminiscent of a numerical PDE solver and showing that the general approach appears to be valid, we consider some more detailed modelling and comment on how this could be used to construct a genuine finite-state cellular automaton

A bilateral shear layer between two parallel Couette flows

We consider a shear layer of a kind not previously studied to our knowledge. Contrary to the classical free shear layer, the width of the shear zone does not vary in the streamwise direction but rather exhibits a lateral variation. Based on some simplifying assumptions, an analytic solution has been derived for the new shear layer. These assumptions have been justified by a comparison with numerical solutions of the full Navier-Stokes equations, which accord with the analytical solution to better than 1% in the entire domain. An explicit formula is found for the width of the shear zone as a function of wall-normal coordinate. This width is independent of wall velocities in the laminar regime. Preliminary results for a co-current laminar-turbulent shear layer in the same geometry are also presented. Shear-layer instabilities were then developed and resulted in an unsteady mixing zone at the interface between the two co-current streams.Comment: 6 pages, 7 figures. Accepted for publication in Phys. Rev.

Bubble-Driven Inertial Micropump

The fundamental action of the bubble-driven inertial micropump is investigated. The pump has no moving parts and consists of a thermal resistor placed asymmetrically within a straight channel connecting two reservoirs. Using numerical simulations, the net flow is studied as a function of channel geometry, resistor location, vapor bubble strength, fluid viscosity, and surface tension. Two major regimes of behavior are identified: axial and non-axial. In the axial regime, the drive bubble either remains inside the channel or continues to grow axially when it reaches the reservoir. In the non-axial regime the bubble grows out of the channel and in all three dimensions while inside the reservoir. The net flow in the axial regime is parabolic with respect to the hydraulic diameter of the channel cross-section but in the non-axial regime it is not. From numerical modeling, it is determined that the net flow is maximal when the axial regime crosses over to the non-axial regime. To elucidate the basic physical principles of the pump, a phenomenological one-dimensional model is developed and solved. A linear array of micropumps has been built using silicon-SU8 fabrication technology, and semi-continuous pumping across a 2 mm-wide channel has been demonstrated experimentally. Measured variation of the net flow with fluid viscosity is in excellent agreement with simulation results.Comment: 18 pages, 18 figures, single colum

Secure Proximity-Based Identity Pairing using an Untrusted Signalling Service

New protocols such as WebRTC promise seamless in-browser peer-to-peer communications that in theory remove the need for third-party services. In practice, widespread use of Firewalls, NATS and dynamic IP addresses mean that overlay addressing or use of some fixed rendezvous point is still needed. In this paper we describe a proximity-based pairing scheme that uses a signalling service to minimise the trust requirements on the third party, achieving anonymity and avoiding the need for PKI, while still requiring only a simple asymmetric pairing protocol

Equation-Free Dynamic Renormalization: Self-Similarity in Multidimensional Particle System Dynamics

We present an equation-free dynamic renormalization approach to the computational study of coarse-grained, self-similar dynamic behavior in multidimensional particle systems. The approach is aimed at problems for which evolution equations for coarse-scale observables (e.g. particle density) are not explicitly available. Our illustrative example involves Brownian particles in a 2D Couette flow; marginal and conditional Inverse Cumulative Distribution Functions (ICDFs) constitute the macroscopic observables of the evolving particle distributions.Comment: 7 pages, 5 figure

Generalization of the JTZ model to open plane wakes

The JTZ model [C. Jung, T. T\'el and E. Ziemniak, Chaos {\bf 3}, (1993) 555], as a theoretical model of a plane wake behind a circular cylinder in a narrow channel at a moderate Reynolds number, has previously been employed to analyze phenomena of chaotic scattering. It is extended here to describe an open plane wake without the confined narrow channel by incorporating a double row of shedding vortices into the intermediate and far wake. The extended JTZ model is found in qualitative agreement with both direct numerical simulations and experimental results in describing streamlines and vorticity contours. To further validate its applications to particle transport processes, the interaction between small spherical particles and vortices in an extended JTZ model flow is studied. It is shown that the particle size has significant influences on the features of particle trajectories, which have two characteristic patterns: one is rotating around the vortex centers and the other accumulating in the exterior of vortices. Numerical results based on the extended JTZ model are found in qualitative agreement with experimental ones in the normal range of particle sizes.Comment: 21 pages, 4 figures, 1 tabl