An automated framework to derive model variables from open transport data using R, PostgreSQL and OpenTripPlanner

This paper outlines a framework that utilises open source software tools to automatically generate the explanatory variables needed for certain transport models, such as mode choice or station choice, from disparate sources of open transport data. A key component of the framework is OpenTripPlanner, an open source multi-modal route planner that builds transport networks using OpenStreetMap, GTFS transit feeds, and digital elevation model data. A case study, applying the framework to generate data for a multinomial logit station choice model, is also described

Earnings and Dividend Announcements is there a Corroboration Effect?

We examine abnormal stock returns surrounding contemporaneous earnings and dividend announcements in order to determine whether investors evaluate the two announcements in relation to each other.We find that there is a statistically significant interaction effect.The abnormal return corresponding to any earnings or dividend announcement depends upon the value of the other announcement. This evidence suggests the existence of a corroborative relationship between the two announcements. Investors give more credence to unanticipated dividend increases or decreases when earnings are also above or below expectations, and vice versa.

The Influence of Extended Cure on Mechanical Performance of Aerospace-Grade Film Adhesives

Bonded adhesive joints have seen increased usage in aircraft structures as weight and cost reductions drive manufacturers to composite designs. As the use of epoxy film adhesives become more prevalent, it is important to characterize the thermal and mechanical properties of the adhesive after exposure to various manufacturing conditions. Prior studies suggest that thermal characteristics and mechanical performance of epoxy resin formulations may be considered a function of chemical structure, cure temperature, and cure duration. It was therefore hypothesized that by controlling cure temperature and duration, the Tg, degree of cure, and mechanical performance of aerospace-grade film adhesives may be controlled. Three epoxy film adhesives cured with three different cure cycles were thermally characterized using DSC, DMA, and rheological techniques. It was shown that increased cure duration provided increased degrees of cure and Tg of the adhesives as a result of a more developed polymer network. V-notch shear and flat-wise tensile testing at ambient dry and elevated temperature wet conditions were used to mechanically characterize the performance of the adhesives cured with three different cure cycles. Mechanical test results showed that adhesives with more aromatic chemical structures saw less degradation as a result of moisture exposure and elevated temperature testing, while the adhesive with simpler chemical structure exhibited significantly reduced performance at elevated temperature wet conditions. It was concluded that while extended cure exposure did not provide significant gains in mechanical performance, the increased polymer network development provided increased resistance to the effects of moisture absorption and elevated temperature environments

Defining probability-based rail station catchments for demand modelling

The aggregate models commonly used in the UK to estimate demand for new local rail stations require the station catchment to be defined first, so that inputs into the model, such as the population from which demand will be generated, can be specified. The methods typically used to define the catchment implicitly assume that station choice is a deterministic process, and that stations exist in isolation from each other. However, studies show that pre-defined catchments account for only 50-60 percent of observed trips, choice of station is not homogeneous within zones, catchments overlap, and catchments vary by access mode and station type. This paper describes early work to implement an alternative probability-based approach, through the development of a station choice prediction model. To derive realistic station access journey explanatory variables, a routable multi-modal network, incorporating data from OpenStreetMap, the Traveline National Data Set and National Rail timetable, was built using OpenTripPlanner and queried using an API wrapper developed in R. Results from a series of multinomial logit models are presented and a method for generating probabilistic catchments using estimated parameter values is described. An example probabilistic catchment is found to provide a realistic representation of the observed catchment, and to perform better than deterministic catchments

An Investigation of the Current Distribution in an HTS Triaxial Power Cable and its Operational Impacts on a Power System

An investigation of the current distribution in a 3-phase triaxial superconducting cable was conducted to study the phase imbalance under steady-state operation and to assist in the construction of a transient model to study operational impacts in a power grid. The triaxial cable consisted of three superconducting concentric phases inside a copper shield, with each phase composed of multiple layers of BSCCO tape wound helically in opposite directions. Current distribution within the cable was determined by using an electric circuit (EC) model containing the self and mutual inductances resulting from both axial and tangential magnetic fields. An AC loss term was also included in the model. Building on the EC model, a lumped cable model was used to investigate the effects of the triaxial cable on a power grid when faults are applied to the system. Cable lengths for future applications (~16 km) were considered. Steady-state simulation of the EC model revealed that the electrical imbalance associated with the phases of the triaxial cable may be negligible for cable lengths less than one mile, but become more of a concern at greater lengths. Transient simulations showed that fault currents approaching 30 kABpeakB may be possible under certain conditions and that resulting induced shield currents may be substantial. Recommendations for further research are provided as well as possible suggestions for alleviating the electrical imbalance

Simulating Quantum Computations on Classical Machines: A Survey

We present a comprehensive study of quantum simulation methods and quantum simulators for classical computers. We first study an exhaustive set of 150+ simulators and quantum libraries. Then, we short-list the simulators that are actively maintained and enable simulation of quantum algorithms for more than 10 qubits. As a result, we realize that most efficient and actively maintained simulators have been developed after 2010. We also provide a taxonomy of the most important simulation methods, namely Schrodinger-based, Feynman path integrals, Heisenberg-based, and hybrid methods. We observe that most simulators fall in the category of Schrodinger-based approaches. However, there are a few efficient simulators belonging to other categories. We also make note that quantum frameworks form their own class of software tools that provide more flexibility for algorithm designers with a choice of simulators/simulation method. Another contribution of this study includes the use and classification of optimization methods used in a variety of simulators. We observe that some state-of-the-art simulators utilize a combination of software and hardware optimization techniques to scale up the simulation of quantum circuits. We summarize this study by providing a roadmap for future research that can further enhance the use of quantum simulators in education and research.Comment: 20 pages, 8 figures, under revie