Commuting flows & local labour markets: Spatial interaction modelling of travel-to-work

One of the most promising approaches to mitigating land-use and transportation problems is continued research on urban commuting. Commuting is essential to many individuals, allowing them to participate in the labour market and earn a living to meet their essential needs. As such, a better understanding of the determinants of commuting will ultimately lead to a better understanding of the complexities of employment, housing, and the many spatial processes underlying commuting. However, in order to understand the commuting process, it is important to examine the milieu within which commuting takes place: the local labour market (LLM). In this thesis, the interplay between commuting and LLMs is explored through the use of regionalisation techniques and spatial interaction models. It is shown that LLM characteristics play a significant role in intra-regional commuting patterns and that a failure to account for LLM conditions may seriously hinder the applicability of models of commuting. Specically, it is found that there are many dierent LLMs across Ireland, and that these LLMs characterise the commuting patterns of population sub-groups. By incorporating these LLMs into models of commuting, this thesis shows that in addition to distance and working population size, the spatial structure of origins and destinations and a number of non-spatial attributes such as unemployment, housing density, and education, all signi- cantly aect commuting ows. Furthermore, the distance decay component of these models appears to be capturing a combination of geographical distance and regional dierentiation due to LLM boundaries, leading to `functional' distance decay. This concept of functional distance decay is a key nding of this thesis, and indicates that in addition to the conguration of origins and destinations, distance decay is also dependent on the spatial structure of LLMs, or more generally, the totality of surrounding conditions within which spatial interaction takes place

Asymptotically Normal Estimation of Local Latent Network Curvature

Network data, commonly used throughout the physical, social, and biological sciences, consist of nodes (individuals) and the edges (interactions) between them. One way to represent the complex, high-dimensional structure in network data is to embed the graph into a low-dimensional geometric space. Curvature of this space, in particular, provides insights about structure in the graph, such as the propensity to form triangles or present tree-like structure. We derive an estimating function for curvature based on triangle side lengths and the midpoints between sides where the only input is a distance matrix and also establish asymptotic normality. We next introduce a novel latent distance matrix estimator for networks as well as an efficient algorithm to compute the estimate via solving iterative quadratic programs. We apply this method to the Los Alamos National Laboratory Unified Network and Host dataset and show how curvature estimates can be used to detect a red-team attack faster than naive methods, as well as discover non-constant latent curvature in coauthorship networks in physics.Comment: 77 page

Inequality and Uncertainty: Theory and Legal Applications

Welfarism is the principle that social policy should be based solely on individual well-being, with no reference to \u27fairness or rights. The propriety of this approach has recently been the subject of extensive debate within legal scholarship. Rather than contributing (directly) to this debate, we identify and analyze a problem within welfarism that has received far too little attentioncall this the ex ante/ex post problem. The problem arises from the combination of uncertainty-an inevitable feature of real policy choice-and a social preference for equality. If the policymaker is not a utilitarian, but rather has a social welfare function that is equity regarding to some degree, then she faces a critical choice. Should she care about the equalization of expected well-being (the ex ante approach), or should she care about the expected equalization of actual well-being (the ex post approach)? Should she focus on the equality of prospects or the prospects for equality? In this Article, we bring the ex ante/ex post problem to the attention of legal academics, provide novel insight into when and why the problem arises, and highlight legal applications where the problem figures prominently. We ultimately conclude that welfarism requires an ex post approach. This is a counterintuitive conclusion, because the ex post approach can conflict with ex ante Pareto superiority. Indeed, this Article demonstrates that the ex post application of every equity-regarding social welfare function-whatever its particular form-must conflict with ex ante Pareto superiority in specific situations. Among other things, then, this Article shows that legal academics who care about equity must abandon either their commitment to welfarism or their commitment to ex ante Pareto superiorit

Inequality and Uncertainty: Theory and Legal Applications

Welfarism is the principle that social policy should be based solely on individual well-being, with no reference to \u27fairness or rights. The propriety of this approach has recently been the subject of extensive debate within legal scholarship. Rather than contributing (directly) to this debate, we identify and analyze a problem within welfarism that has received far too little attentioncall this the ex ante/ex post problem. The problem arises from the combination of uncertainty-an inevitable feature of real policy choice-and a social preference for equality. If the policymaker is not a utilitarian, but rather has a social welfare function that is equity regarding to some degree, then she faces a critical choice. Should she care about the equalization of expected well-being (the ex ante approach), or should she care about the expected equalization of actual well-being (the ex post approach)? Should she focus on the equality of prospects or the prospects for equality? In this Article, we bring the ex ante/ex post problem to the attention of legal academics, provide novel insight into when and why the problem arises, and highlight legal applications where the problem figures prominently. We ultimately conclude that welfarism requires an ex post approach. This is a counterintuitive conclusion, because the ex post approach can conflict with ex ante Pareto superiority. Indeed, this Article demonstrates that the ex post application of every equity-regarding social welfare function-whatever its particular form-must conflict with ex ante Pareto superiority in specific situations. Among other things, then, this Article shows that legal academics who care about equity must abandon either their commitment to welfarism or their commitment to ex ante Pareto superiorit

SEIS: Insight's Seismic Experiment for Internal Structure of Mars.

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w ∼ 3 at 40 ∘ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.Electronic supplementary materialThe online version of this article (10.1007/s11214-018-0574-6) contains supplementary material, which is available to authorized users

Colocation aware content sharing in urban transport

People living in urban areas spend a considerable amount of time on public transport. During these periods, opportunities for inter-personal networking present themselves, as many of us now carry electronic devices equipped with Bluetooth or other wireless capabilities. Using these devices, individuals can share content (e.g., music, news or video clips) with fellow travellers that happen to be on the same train or bus. Transferring media takes time; in order to maximise the chances of successfully completing interesting downloads, users should identify neighbours that possess desirable content and who will travel with them for long-enough periods. In this thesis, a peer-to-peer content distribution system for wireless devices is proposed, grounded on three main contributions: (1) a technique to predict colocation durations (2) a mechanism to exclude poorly performing peers and (3) a library advertisement protocol. The prediction scheme works on the observation that people have a high degree of regularity in their movements. Ensuring that content is accurately described and delivered is a challenge in open networks, requiring the use of a trust framework, to avoid devices that do not behave appropriately. Content advertising methodologies are investigated, showing their effect on whether popular material or niche tastes are disseminated. We first validate our assumptions on synthetic and real datasets, particularly movement traces that are comparable to urban environments. We then illustrate real world operation using measurements from mobile devices running our system in the proposed environment. Finally, we demonstrate experimentally on these traces that our content sharing system significantly improves data communication efficiency, and file availability compared to naive approaches

The Multi-Agent Transport Simulation MATSim

"The MATSim (Multi-Agent Transport Simulation) software project was started around 2006 with the goal of generating traffic and congestion patterns by following individual synthetic travelers through their daily or weekly activity programme. It has since then evolved from a collection of stand-alone C++ programs to an integrated Java-based framework which is publicly hosted, open-source available, automatically regression tested. It is currently used by about 40 groups throughout the world. This book takes stock of the current status. The first part of the book gives an introduction to the most important concepts, with the intention of enabling a potential user to set up and run basic simulations.The second part of the book describes how the basic functionality can be extended, for example by adding schedule-based public transit, electric or autonomous cars, paratransit, or within-day replanning. For each extension, the text provides pointers to the additional documentation and to the code base. It is also discussed how people with appropriate Java programming skills can write their own extensions, and plug them into the MATSim core. The project has started from the basic idea that traffic is a consequence of human behavior, and thus humans and their behavior should be the starting point of all modelling, and with the intuition that when simulations with 100 million particles are possible in computational physics, then behavior-oriented simulations with 10 million travelers should be possible in travel behavior research. The initial implementations thus combined concepts from computational physics and complex adaptive systems with concepts from travel behavior research. The third part of the book looks at theoretical concepts that are able to describe important aspects of the simulation system; for example, under certain conditions the code becomes a Monte Carlo engine sampling from a discrete choice model. Another important aspect is the interpretation of the MATSim score as utility in the microeconomic sense, opening up a connection to benefit cost analysis. Finally, the book collects use cases as they have been undertaken with MATSim. All current users of MATSim were invited to submit their work, and many followed with sometimes crisp and short and sometimes longer contributions, always with pointers to additional references. We hope that the book will become an invitation to explore, to build and to extend agent-based modeling of travel behavior from the stable and well tested core of MATSim documented here.