Allocation in Practice

How do we allocate scarcere sources? How do we fairly allocate costs? These are two pressing challenges facing society today. I discuss two recent projects at NICTA concerning resource and cost allocation. In the first, we have been working with FoodBank Local, a social startup working in collaboration with food bank charities around the world to optimise the logistics of collecting and distributing donated food. Before we can distribute this food, we must decide how to allocate it to different charities and food kitchens. This gives rise to a fair division problem with several new dimensions, rarely considered in the literature. In the second, we have been looking at cost allocation within the distribution network of a large multinational company. This also has several new dimensions rarely considered in the literature.Comment: To appear in Proc. of 37th edition of the German Conference on Artificial Intelligence (KI 2014), Springer LNC

Gentrifying with family wealth:Parental gifts and neighbourhood sorting among young adult owner-occupants

This paper assesses the role of parental gifts in neighbourhood sorting among young adult homebuyers. We make use of high-quality individual-level registry data for two large urban metropolitan areas in the Netherlands. While previous studies have shown that young adults receiving gifts purchase more expensive housing, little is known about the role of gifts in where young adults buy. Our study finds that parental gifts flow into the housing market in a spatially-uneven way. Movers supported by substantial parental gifts are more likely to enter owner-occupied housing in high-status and gentrifying urban neighbourhoods compared to movers without gifts. This study shows that this can only partially be explained by household and parental characteristics and by the uneven distribution of housing values. The remaining effect suggests that parental gifts also play a role in trade-offs regarding spatial residential decision-making. The conclusion discusses the ramifications of our findings for debates on (re)production of class and intra-generational inequalities through housing, and provides avenues for further research

Number Partitioning on a Quantum Computer

We present an algorithm to compute the number of solutions of the (constrained) number partitioning problem. A concrete implementation of the algorithm on an Ising-type quantum computer is given.Comment: 5 pages, 1 figure, see also http://rugth30.phys.rug.nl/compphys/qce.ht

Random Costs in Combinatorial Optimization

The random cost problem is the problem of finding the minimum in an exponentially long list of random numbers. By definition, this problem cannot be solved faster than by exhaustive search. It is shown that a classical NP-hard optimization problem, number partitioning, is essentially equivalent to the random cost problem. This explains the bad performance of heuristic approaches to the number partitioning problem and allows us to calculate the probability distributions of the optimum and sub-optimum costs.Comment: 4 pages, Revtex, 2 figures (eps), submitted to PR

Exponentially hard problems are sometimes polynomial, a large deviation analysis of search algorithms for the random Satisfiability problem, and its application to stop-and-restart resolutions

A large deviation analysis of the solving complexity of random 3-Satisfiability instances slightly below threshold is presented. While finding a solution for such instances demands an exponential effort with high probability, we show that an exponentially small fraction of resolutions require a computation scaling linearly in the size of the instance only. This exponentially small probability of easy resolutions is analytically calculated, and the corresponding exponent shown to be smaller (in absolute value) than the growth exponent of the typical resolution time. Our study therefore gives some theoretical basis to heuristic stop-and-restart solving procedures, and suggests a natural cut-off (the size of the instance) for the restart.Comment: Revtex file, 4 figure

Infrared Thermography as a Diagnostic Tool for Pododermatitis in Captive Greater Flamingos (Phoenicopterus roseus)

This cross-sectional study investigated the use of infrared thermography as a diagnostic tool for pododermatitis in captive greater flamingos (Phoenicopterus roseus). Photographs and thermal images were obtained for 775 feet from 408 flamingos held at three UK zoological collections. The feet were divided into eight regions, which were assigned a score for hyperkeratosis, fissures, nodules and papillomatous growths according to a previously defined scoring system. Minimum, mean and maximum temperatures were recorded for each region. 97 feet (12.5%) were scored as normal (no lesions or only mild hyperkeratosis), whilst 678 (87.5%) were scored as abnormal. It was found that 99.9% (95% confidence interval (CI): 99.3–100%) of the scored feet exhibited hyperkeratosis, 61.7% (95% CI: 58.2–65.1%) fissures, 16.0% (95% CI: 13.5–18.8%) nodules and 38.5% (95% CI: 35.0–42.0%) papillomatous growths. Thermal data assessed using general linear mixed effect modelling showed that regional and individual bird temperature differences accounted for most of the temperature variation, but there was a statistically significant (P<0.05) difference between regions with nodules versus regions without when using maximum temperatures. Intra- and inter-foot variation, using a regional correction factor and ankle temperatures, was assessed for 272 birds, where temperature distributions for each lesion type were compared with that of normal regions using t-tests. A statistically significant difference (P<0.05) was found between corrected values for regions with hyperkeratosis and papillomatous growths compared with normal, but no difference was found for fissures or nodules. Despite the differences found, the results suggest that infrared thermography may not be a practical diagnostic tool for pododermatitis in flamingos due to wide temperature variations between and within normal feet and a great degree of overlap of temperatures between normal and abnormal feet

Petrophysical interpretation of selected wells near Liverpool for the UK Geoenergy Observatories project

This report details the petrophysical evaluation of 2 onshore wells near Liverpool UK: Kemira 1 (SJ47NE/101) and Ince Marshes 1 (SJ47NE/100). The results contribute to the geological characterisation for a monitoring experiment in Cheshire for the UK Geoenergy Observatories project. The evaluation is based on the petrophysical interpretation of available digital wireline log curve data for the two wells across the whole logged interval (according to reinterpreted stratigraphic formations defined and correlated for this project). Associated digitised sample data (XRD, XRF, TOC data) is available to help cross-validate the interpretation for 1 of the 2 wells. Outputs for this evaluation include continuous (along borehole) interpretations of clay volume, porosity, and total organic carbon (TOC). These interpreted curves were used to examine the proportions of reservoir rock and shale for each formation in each well and their respective properties. Net reservoir intervals were defined by those intervals where the clay volume was less than 50%, the porosity was more than 5% and no coal intervals were present. Net Shale intervals were defined by those intervals where the clay volume was more than 50% and no coal intervals were present. The Kemira 1 well was logged from the Triassic Bromsgrove Sandstone Formation down to the Carboniferous Westphalian A unit, the base of which is not penetrated (~1400 m logged between 32-1433 m). Data is somewhat limited compared to the Ince Marshes 1 well, comprising parts of a standard log suite, and the curve data is machine-digitised from the legacy log field prints. (Resistivity curves are only available over part of the well; the neutron log was recorded in sandstone matrix units and the specific transformation to limestone matrix units (required for the interpretation) is unknown and has been guessed at; there is less data available for this well in terms of ancillary curves or sample analysis to cross check results than for the Ince Marshes 1 well). The results of the interpretation for this well should therefore be treated with appropriate caution. The Ince Marshes 1 well was logged over the Carboniferous interval comprising the Westphalian C-A and the Millstone Grit Group, the base of which may be drilled through, but was unable to be logged due to hole difficulties (~1084 m logged between 368-1452 m). This well was drilled and logged more recently than the Kemira 1 well and has much more associated data including more advanced logging tools such as image logs, dipole sonic, and elemental spectroscopy to give formation mineral compositions. Sidewall cores were also collected and these and drill cuttings were analysed using various techniques to determine mineral, elemental and total organic carbon contents at the sample depths. There is therefore much more data available with which to cross check and verify results and as such the results of the interpretation can be regarded with a higher level of confidence than those of the Kemira 1 well. The Kemira 1 well contains strata of Permian and Triassic age. These have high reservoir net to gross (NTG) values of 0.99 or 1 (i.e. 100% net reservoir). Their average porosities range from 18- 25% and the Sherwood Sandstone Formation shows the highest average porosity at 25%. Both wells contain older, Carboniferous rocks and these have much lower NTG values, all containing less than 50% reservoir rocks (NTG ranging from 0.08-0.41). Their porosities are also lower, ranging from 8-15%, apart from the Westphalian C unit in the Kemira 1 well, which are anomalously high (23%) resulting from the presence of coal intervals and porosity artefacts adjacent to them (a software/parameter selection limitation Total organic carbon (TOC) was calculated for the rocks beneath the Westphalian B unit in the Ince Marshes 1 well. Shales with TOC values calculated as greater than 1.5 wt% were considered ‘TOC-rich’. The ratio of these to the total formation thicknesses are generally very low: 0.08-0.15 for the Westphalian A and 0.11-0.24 for the Millstone Grit. The lower end of the range is where a OR/17/037; Draft 0.1 Last modified: 2017/05/04 10:09 2 minimum shale thickness cut-off of 2 m is considered. The TOC rich shale in the Westphalian A has an average of 3.38 wt% TOC. However, individual intervals within the unit show typical curve responses for a mature source interval containing hydrocarbons and reach TOC values up to 9.18 wt%. The TOC rich shales in the Millstone Grit have an average of 2.9 wt% TOC. The TOC values measured in samples from sidewall cores and cuttings extend beneath the base of the geophysical well logs to 1575 m. There are 44 measured values averaging 2.89 wt% TOC with a maximum of 6.93 wt% TOC

On The Complexity and Completeness of Static Constraints for Breaking Row and Column Symmetry

We consider a common type of symmetry where we have a matrix of decision variables with interchangeable rows and columns. A simple and efficient method to deal with such row and column symmetry is to post symmetry breaking constraints like DOUBLELEX and SNAKELEX. We provide a number of positive and negative results on posting such symmetry breaking constraints. On the positive side, we prove that we can compute in polynomial time a unique representative of an equivalence class in a matrix model with row and column symmetry if the number of rows (or of columns) is bounded and in a number of other special cases. On the negative side, we show that whilst DOUBLELEX and SNAKELEX are often effective in practice, they can leave a large number of symmetric solutions in the worst case. In addition, we prove that propagating DOUBLELEX completely is NP-hard. Finally we consider how to break row, column and value symmetry, correcting a result in the literature about the safeness of combining different symmetry breaking constraints. We end with the first experimental study on how much symmetry is left by DOUBLELEX and SNAKELEX on some benchmark problems.Comment: To appear in the Proceedings of the 16th International Conference on Principles and Practice of Constraint Programming (CP 2010

Fingerprint oxygen redox reactions in batteries through high-efficiency mapping of resonant inelastic X-ray scattering

Realizing reversible reduction-oxidation (redox) reactions of lattice oxygen in batteries is a promising way to improve the energy and power density. However, conventional oxygen absorption spectroscopy fails to distinguish the critical oxygen chemistry in oxide-based battery electrodes. Therefore, high-efficiency full-range mapping of resonant inelastic X-ray scattering (mRIXS) has been developed as a reliable probe of oxygen redox reactions. Here, based on mRIXS results collected from a series of Li Ni Co Mn O electrodes at different electrochemical states and its comparison with peroxides, we provide a comprehensive analysis of five components observed in the mRIXS results. While all the five components evolve upon electrochemical cycling, only two of them correspond to the critical states associated with oxygen redox reactions. One is a specific feature at 531.0 eV excitation and 523.7 eV emission energy, the other is a low-energy loss feature. We show that both features evolve with electrochemical cycling of Li Ni Co Mn O electrodes, and could be used for characterizing oxidized oxygen states in the lattice of battery electrodes. This work provides an important benchmark for a complete assignment of all mRIXS features collected from battery materials, which sets a general foundation for future studies in characterization, analysis, and theoretical calculation for probing and understanding oxygen redox reactions. 1.17 0.21 0.08 0.54 2 1.17 0.21 0.08 0.54