Models and Strategies for Variants of the Job Shop Scheduling Problem

Recently, a variety of constraint programming and Boolean satisfiability approaches to scheduling problems have been introduced. They have in common the use of relatively simple propagation mechanisms and an adaptive way to focus on the most constrained part of the problem. In some cases, these methods compare favorably to more classical constraint programming methods relying on propagation algorithms for global unary or cumulative resource constraints and dedicated search heuristics. In particular, we described an approach that combines restarting, with a generic adaptive heuristic and solution guided branching on a simple model based on a decomposition of disjunctive constraints. In this paper, we introduce an adaptation of this technique for an important subclass of job shop scheduling problems (JSPs), where the objective function involves minimization of earliness/tardiness costs. We further show that our technique can be improved by adding domain specific information for one variant of the JSP (involving time lag constraints). In particular we introduce a dedicated greedy heuristic, and an improved model for the case where the maximal time lag is 0 (also referred to as no-wait JSPs).Comment: Principles and Practice of Constraint Programming - CP 2011, Perugia : Italy (2011

Off-the-shelf Non-Intrusive Load Monitoring Devices Utilised in a Low Activity Detection Service

There is a growing awareness for the need to provide low cost solutions for the care of the elderly and in particular to allow them to keep living independent lives. In parallel to this there has also been significant advances in a number of technical areas including 1) monitoring electricity consumption for the purpose of reducing power costs, 2) non-intrusive load monitoring (NILM), 3) using sensors to determine activities of daily living and 4) cloud computing. The purpose of this work was to demonstrate that it is possible to use a readily available consumer off the shelf electricity monitor to provide a low intrusive activity monitor for older persons. This work uses the Design Science Research Methodology and builds on the results of our previous work that used raw electricity usage data. In this work we are trailing the use of a meter that uses NILM to identify individual appliances in the home. The information on appliance use was analysed by a cloud base program and alerts were sent to the carer when lower than expected activity was detected. Participants both in this work and those reported in the literature have mentioned the annoyance of having multiple sensors in a home, especially if they emit either constant or flashing light. In contrast NILM allows the use of multiple electrical appliances to be monitored without the need for a large number of sensors to be deployed – just one sensor at the meter or fuse board. The confluence of a number of technologies has enabled the creation of a low intrusive and low cost monitoring system to have become a reality. The initial trial of the system has been shown to be a mostly reliable alternative to a system built on multiple sensors. Based on previous work that involved the deployment of multiple sensors, the new system is expected to be more acceptable as it has the desired attribute of becoming invisible to the user

A minimally intrusive monitoring system that utilizes electricity consumption as a proxy for wellbeing

The purpose of this work was to test the hypothesis: `Off-the-shelf domestic electricity meters can be utilised to assist in monitoring the wellbeing of elderly people` Many studies have shown that it is, in theory, possible to use domestic electricity consumption to determine `activities of daily living` but the availability of systems for actual use is very limited. This work followed the Design Science Research Methodology to create a Java application running on the Google App Engine cloud service that interfaced with both electricity meters and voice and text services. The system was implemented and tested over a three month period with one older person and their carer. Results demonstrated that the technology readily succeeds in meeting the study`s initial objectives. The need for more sophisticated decision logic was apparent and a method to determine whether a home is currently occupied is likely to improve the ability to create more timely alerts

Investigation on the Mechanical and Tribological Properties of Aluminium-Tin Based Plain Bearing Material

The purpose of this study is to investigate the Mechanical and Tribological properties of plain bearing alloys used especially in internal combustion engines. The mechanical properties namely Tensile strength and Hardness were investigated according to standard procedure. The sliding friction and wear properties of aluminium-tin alloy against high carbon high chromium steel were investigated at different normal loads as (29.43 N, 33.35 N and 36.25 N). Tests were carried in oil lubricated conditions with a sliding speed of 1 m/s. Prior to experimentation, the circulating engine oil 20w40 was heated to temperature of 800C using heater. The frictional behavior and wear property of aluminium-tin alloy were studied by means of pin-on-disk tribometer. The weight loss of the specimen was measured and wear and friction characteristics were calculated with respect to time, depth of wear track, sliding speed and bearing load. To determine the wear mechanism, the worn surfaces of the samples were examined using Scanning Electron Microscope (SEM). The optimum wear reduction was obtained at different normal loads and at same sliding speed

Beating dark-dark solitons in Bose-Einstein condensates

Motivated by recent experimental results, we study beating dark-dark solitons as a prototypical coherent structure that emerges in two-component Bose-Einstein condensates. We showcase their connection to dark- bright solitons via SO(2) rotation, and infer from it both their intrinsic beating frequency and their frequency of oscillation inside a parabolic trap. We identify them as exact periodic orbits in the Manakov limit of equal inter- and intra-species nonlinearity strengths with and without the trap and showcase the persistence of such states upon weak deviations from this limit. We also consider large deviations from the Manakov limit illustrating that this breathing state may be broken apart into dark-antidark soliton states. Finally, we consider the dynamics and interactions of two beating dark-dark solitons in the absence and in the presence of the trap, inferring their typically repulsive interaction.Comment: 13 pages, 14 figure

Assisted Living: Domestic Power Monitoring utilising Home Automation Products and Cloud Storage

This paper describes the development of a system for taking measurements of electrical power consumption in a domestic situation and using a web service to store the measurements in a cloud hosted database. This is part of a larger project to evaluate the potential for using power monitoring as a proxy for wellness as part of the assisted living projects at Wintec

An Atomic Gravitational Wave Interferometric Sensor in Low Earth Orbit (AGIS-LEO)

We propose an atom interferometer gravitational wave detector in low Earth orbit (AGIS-LEO). Gravitational waves can be observed by comparing a pair of atom interferometers separated over a ~30 km baseline. In the proposed configuration, one or three of these interferometer pairs are simultaneously operated through the use of two or three satellites in formation flight. The three satellite configuration allows for the increased suppression of multiple noise sources and for the detection of stochastic gravitational wave signals. The mission will offer a strain sensitivity of < 10^(-18) / Hz^(1/2) in the 50 mHz - 10 Hz frequency range, providing access to a rich scientific region with substantial discovery potential. This band is not currently addressed with the LIGO or LISA instruments. We analyze systematic backgrounds that are relevant to the mission and discuss how they can be mitigated at the required levels. Some of these effects do not appear to have been considered previously in the context of atom interferometry, and we therefore expect that our analysis will be broadly relevant to atom interferometric precision measurements. Finally, we present a brief conceptual overview of shorter-baseline (< 100 m) atom interferometer configurations that could be deployed as proof-of-principle instruments on the International Space Station (AGIS-ISS) or an independent satellite.Comment: 37 pages, 21 figure

Theoretical Bounds on Control-Plane Self-Monitoring in Routing Protocols

Routing protocols rely on the cooperation of nodes in the network to both forward packets and to select the forwarding routes. There have been several instances in which an entire network's routing collapsed simply because a seemingly insignificant set of nodes reported erroneous routing information to their neighbors. It may have been possible for other nodes to trigger an automated response and prevent the problem by analyzing received routing information for inconsistencies that revealed the errors. Our theoretical study seeks to understand when nodes can detect the existence of errors in the implementation of route selection elsewhere in the network through monitoring their own routing states for inconsistencies. We start by constructing a methodology, called Strong-Detection, that helps answer the question. We then apply Strong-Detection to three classes of routing protocols: distance-vector, path-vector, and link-state. For each class, we derive low-complexity, self-monitoring algorithms that use the routing state created by these routing protocols to identify any detectable anomalies. These algorithms are then used to compare and contrast the self-monitoring power these various classes of protocols possess. We also study the trade-off between their state-information complexity and ability to identify routing anomalies