Universality of collapsing two-dimensional self-avoiding trails

Results of a numerically exact transfer matrix calculation for the model of Interacting Self-Avoiding Trails are presented. The results lead to the conclusion that, at the collapse transition, Self-Avoiding Trails are in the same universality class as the O(n=0) model of Blote and Nienhuis (or vertex-interacting self-avoiding walk), which has thermal exponent $\nu=12/23$, contrary to previous conjectures.Comment: Final version, accepted for publication in Journal of Physics A; 9 pages; 3 figure

Using baseline-dependent window functions for data compression and field-of-interest shaping in radio interferometry

In radio interferometry, observed visibilities are intrinsically sampled at some interval in time and frequency. Modern interferometers are capable of producing data at very high time and frequency resolution; practical limits on storage and computation costs require that some form of data compression be imposed. The traditional form of compression is a simple averaging of the visibilities over coarser time and frequency bins. This has an undesired side effect: the resulting averaged visibilities "decorrelate", and do so differently depending on the baseline length and averaging interval. This translates into a non-trivial signature in the image domain known as "smearing", which manifests itself as an attenuation in amplitude towards off-centre sources. With the increasing fields of view and/or longer baselines employed in modern and future instruments, the trade-off between data rate and smearing becomes increasingly unfavourable. In this work we investigate alternative approaches to low-loss data compression. We show that averaging of the visibility data can be treated as a form of convolution by a boxcar-like window function, and that by employing alternative baseline-dependent window functions a more optimal interferometer smearing response may be induced. In particular, we show improved amplitude response over a chosen field of interest, and better attenuation of sources outside the field of interest. The main cost of this technique is a reduction in nominal sensitivity; we investigate the smearing vs. sensitivity trade-off, and show that in certain regimes a favourable compromise can be achieved. We show the application of this technique to simulated data from the Karl G. Jansky Very Large Array (VLA) and the European Very-long-baseline interferometry Network (EVN)

Properties of nonaqueous electrolytes Quarterly report, 20 Jun. - 19 Sep. 1967

Electrolyte preparation, and physical property and nuclear magnetic resonance structural studies of nonaqueous electrolyte

Water tables in marine beaches

Beach slopes, sand movements, and sand composition have been studied by a number of organizations and individuals, but the interstitial water and the possible interrelations between beach characteristics and changing water levels within the beach seem to have received little attention...

From Physical to Cyber: Escalating Protection for Personalized Auto Insurance

Nowadays, auto insurance companies set personalized insurance rate based on data gathered directly from their customers' cars. In this paper, we show such a personalized insurance mechanism -- wildly adopted by many auto insurance companies -- is vulnerable to exploit. In particular, we demonstrate that an adversary can leverage off-the-shelf hardware to manipulate the data to the device that collects drivers' habits for insurance rate customization and obtain a fraudulent insurance discount. In response to this type of attack, we also propose a defense mechanism that escalates the protection for insurers' data collection. The main idea of this mechanism is to augment the insurer's data collection device with the ability to gather unforgeable data acquired from the physical world, and then leverage these data to identify manipulated data points. Our defense mechanism leveraged a statistical model built on unmanipulated data and is robust to manipulation methods that are not foreseen previously. We have implemented this defense mechanism as a proof-of-concept prototype and tested its effectiveness in the real world. Our evaluation shows that our defense mechanism exhibits a false positive rate of 0.032 and a false negative rate of 0.013.Comment: Appeared in Sensys 201

Fibres as shear reinforcement in RC beams: an overview on assessment of material properties and design approaches

It is recognized that understanding at a material level is needed in the development of rational, physical-mechanical, models for predicting the behaviour of fibre reinforced concrete at service and strength limit conditions. To this end, understanding the post-cracking mechanisms of the fibres, and their symbiotic relationship with the cementitious matrix that surrounds them, is required for the development of realistic modelling approaches that accurately represent empirical observations. Several experimental test setups and inverse analysis procedures have been proposed to derive the fundamental stress-crack width (–w) law, but a consensus still does not exists on the best strategy for its determination. In structures governed by shear, fibre reinforcement increases the stiffness and shear stress transfer across a crack, but a methodology to capture the contribution of fibres in this regards is challenging. To overcome this, a clear strategy is needed in deriving relationships that simulate fibre reinforcement mechanisms in the mobilized fracture modes and, also, develop design approaches capable of capturing the relevant contributions of the fibres. This study firstly reviews current inverse analysis models used to describe the tensile (Model I fracture) relationship for FRC and, secondly, discusses a newly proposed model, referred to as the integrated shear model (ISM). The ISM is developed from mesoscale observations from gamma- and X-ray imaging on FRC elements under Modes I and II fracture conditions. The resulting model is compared to test data reported in the literature and a good correlation is observed.The authors wish to acknowledge the grant SFRH/BSAB/114302/2016 provided by FCT and the Australian Research Council grant DP150104107, as well as the support provided by the UNSW for the research activities carried out under the status of Visiting Professorial Fellow for the first author. The support of the FCT through the project PTDC/ECM EST/2635/2014 is also acknowledged

An integrated approach for predicting the shear capacity of fibre reinforced concrete beams

This paper describes the development of an integrated design approach for determining shear capacity of flexurally reinforced steel fibre reinforced concrete members. The approach considers fibre distribution profile, fibre pull-out resistance and the modified compression field theory integrated using a comprehensive strategy. To assess the performance of the developed model, a database consisting of 122 steel fibre reinforced and prestressed concrete beams failing in shear was assembled from available literature. The model predictions were shown to correlate well with the test data. The performance of the analytical model was also compared to predictions attained by the two approaches recommended by the fib Model Code 2010, one based on an empirical equation and the other on the modified compression field theory approach. The predictive performance of the proposed approach was also assessed by using the Demerit Points Classification (DPC), being the prediction as better as lower is the total penalty points provided by the classification. The model developed in this paper demonstrated a superior performance to those of the Model Code, with a higher predictive performance in terms of safety and reliability.The authors wish to acknowledge the grant SFRH/BSAB/114302/2016 provided by FCT and the Australian Research Council grant DP150104107, as well as the support provided by the UNSW Sydney for the research activities carried out under the status of Visiting Professorial Fellow for the first author. The support of the FCT through the project PTDC/ECM-EST/2635/2014 is also acknowledged.info:eu-repo/semantics/publishedVersio

Properties of nonaqueous electrolytes Sixth summary report, 20 Sep. 1967 - 19 Mar. 1968

Physical properties and structural studies on propylene carbonate, dimethyl formamide, and acetonitrile solvent electrolyte