Hope for the Best, Prepare for the Worst: Response of Tall Steel Buildings to the ShakeOut Scenario Earthquake

This work represents an effort to develop one plausible realization of the effects of the scenario event on tall steel moment-frame buildings. We have used the simulated ground motions with three-dimensional nonlinear finite element models of three buildings in the 20-story class to simulate structural responses at 784 analysis sites spaced at approximately 4 km throughout the San Fernando Valley, the San Gabriel Valley, and the Los Angeles Basin. Based on the simulation results and available information on the number and distribution of steel buildings, the recommended damage scenario for the ShakeOut drill was 5% of the estimated 150 steel moment-frame structures in the 10–30 story range collapsing, 10% red-tagged, 15% with damage serious enough to cause loss of life, and 20% with visible damage requiring building closure

A relation between moduli space of D-branes on orbifolds and Ising model

We study D-branes transverse to an abelian orbifold C^3/Z_n Z_n. The moduli space of the gauge theory on the D-branes is analyzed by combinatorial calculation based on toric geometry. It is shown that the calculation is related to a problemto count the number of ground states of an antiferromagnetic Ising model. The lattice on which the Ising model is defined is a triangular one defined on the McKay quiver of the orbifold.Comment: 20 pages, 13 figure

Microfluidic droplet control by photothermal interfacial flow

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Droplet-based microfluidics is an emerging field that can perform a variety of discrete operation of tiny amount of reagent or individual cell. Noncontact manipulation of droplets in a microfluidic platform can be achieved by using the Marangoni convection due to a local temperature gradient given by the irradiation of heating light. This method provides noncontact, selective and flexible manipulation for droplets flowing in microfluidic network. Although the potential of this selective operation method of droplets was confirmed, the driving force exerted on droplets has not been quantitatively obtained. In this study, we have developed a measurement system of the temperature field around droplets during the manipulation by light irradiation and evaluated the manipulation force. In O/W emulsion system with oleic acid and buffer solution, oleic acid for droplet and buffer solution for continuous phase, the temperature distribution around the droplets was measured by laser-induced fluorescence. From the balance of drag force and photo-induced Marangoni force, the driving force was determined. From the results, we confirmed the applicability of the noncontact droplet manipulation using the photothermal Marangoni effect

Role of three-body interactions in formation of bulk viscosity in liquid argon

With the aim of locating the origin of discrepancy between experimental and computer simulation results on bulk viscosity of liquid argon, a molecular dynamic simulation of argon interacting via ab initio pair potential and triple-dipole three-body potential has been undertaken. Bulk viscosity, obtained using Green-Kubo formula, is different from the values obtained from modeling argon using Lennard-Jones potential, the former being closer to the experimental data. The conclusion is made that many-body inter-atomic interaction plays a significant role in formation of bulk viscosity.Comment: 4 pages, 3 figure

Application of Stochastic Simulation Methods to System Identification

Reliable predictive models for the response of structures are a necessity for many branches of earthquake engineering, such as design, structural control, and structural health monitoring. However, the process of choosing an appropriate class of models to describe a system, known as model-class selection, and identifying the specific predictive model based on available data, known as system identification, is difficult. Variability in material properties, complex constitutive behavior, uncertainty in the excitations caused by earthquakes, and limited constraining information (relatively few channels of data, compared to the number of parameters needed for a useful predictive model) make system identification an ill-conditioned problem. In addition, model-class selection is not trivial, as it involves balancing predictive power with simplicity. These problems of system identification and model-class selection may be addressed using a Bayesian probabilistic framework that provides a rational, transparent method for combining prior knowledge of a system with measured data and for choosing between competing model classes. The probabilistic framework also allows for explicit quantification of the uncertainties associated with modeling a system. The essential idea is to use probability logic and Bayes' Theorem to give a measure of plausibility for a model or class of models that is updated with available data. Similar approaches have been used in the field of system identification, but many currently used methods for Bayesian updating focus on the model defined by the set of most plausible parameter values. The challenge for these approaches (referred to as asymptotic-approximation-based methods) is when one must deal with ill-conditioned problems, where there may be many models with high plausibility, rather than a single v dominant model. It is demonstrated here that ill-conditioned problems in system identification and model-class selection can be effectively addressed using stochastic simulation methods. This work focuses on the application of stochastic simulation to updating and comparing model classes in problems of: (1) development of empirical ground motion attenuation relations, (2) structural model updating using incomplete modal data for the purposes of structural health monitoring, and (3) identification of hysteretic structural models, including degrading models, from seismic structural response. The results for system identification and model-class selection in this work fall into three categories. First, in cases where the existing asymptotic approximation-based methods are appropriate (i.e., well-conditioned problems with one highest-plausibility model), the results obtained using stochastic simulation show good agreement with results from asymptotic-approximation-based methods. Second, for cases involving ill-conditioned problems based on simulated data, stochastic simulation methods are successfully applied to obtain results in a situation where the use of asymptotics is not feasible (specfically, the identification of hysteretic models). Third, preliminary studies using stochastic simulation to identify a deteriorating hysteretic model with relatively sparse real data from a structure damaged in the 1994 Northridge earthquake show that the high-plausibility models demonstrate behavior consistent with the observed damage, indicating that there is promise in applying these methods to ill-conditioned problems in the real world

Body Parts and Their Epic Struggle in Ovid’s Amores

This thesis examines how body parts in Ovid’s Amores provide the location for an epic battle between the conflicting genres of Tragedy and Elegy. The first chapter summarizes past Ovidian scholarship. The second chapter examines how Ovid separates body parts of the amator and the puella in Amores 1.4 and 1.5 in order to deny the lovers complete unification. The third chapter expands the conclusion of the second by analyzing poems in Books 2 and 3, which contain a significant number of body parts, to determine how the amator’s interaction with the puella’s body parts reflects his lack of union with her in public and private spheres. The fourth chapter rereads the puella’s body parts, and the amator’s relationship with them, with a view to establish the puella as either Tragedy or Elegy and to theorize how the amator’s relationship with the puella symbolizes the poeta’s relationship with his poetry

Response of tall steel buildings in southern California to the magnitude 7.8 shakeout scenario earthquake

Currently, there is a significant campaign being undertaken in southern California to increase public awareness and readiness for the next large earthquake along the San Andreas Fault, culminating in a large-scale earthquake response exercise. The USGS ShakeOut scenario is a key element to understanding the likely effects of such an event. A source model for a M7.8 scenario earthquake has been created (Hudnet et al. 2007), and used in conjunction with a velocity model for southern California to generate simulated ground motions for the event throughout the region (Graves et al. 2008). We were charged by the USGS to provide one plausible realization of the effects of the scenario event on tall steel moment-frame buildings. We have used the simulated ground motions with three-dimensional non-linear finite element models of three buildings (in two orthogonal orientations and two different connection fragility conditions, for a total of twelve cases) in the 20-story class to simulate structural responses at 784 analysis sites spaced at approximately 4 km throughout the San Fernando Valley, the San Gabriel Valley and the Los Angeles Basin. Based on the simulation results and available information on the number and distribution of steel buildings, we have recommended that the ShakeOut drill be planned with a damage scenario comprising of 5% of the estimated 150 steel moment frame structures in the 10-30 story range collapsing (8 collapses), 10% of the structures red-tagged (16 red-tagged buildings), 15% of the structures with damage serious enough to cause loss of life (24 buildings with fatalities), and 20% of the structures with visible damage requiring building closure (32 buildings with visible damage and possible injuries). This paper details the analytical study underlying these recommendations

Phase transitions in systems with two species of molecular motors

Systems with two species of active molecular motors moving on (cytoskeletal) filaments into opposite directions are studied theoretically using driven lattice gas models. The motors can unbind from and rebind to the filaments. Two motors are more likely to bind on adjacent filament sites if they belong to the same species. These systems exhibit (i) Continuous phase transitions towards states with spontaneously broken symmetry, where one motor species is largely excluded from the filament, (ii) Hysteresis of the total current upon varying the relative concentrations of the two motor species, and (iii) Coexistence of traffic lanes with opposite directionality in multi-filament systems. These theoretical predictions should be experimentally accessible.Comment: 7 pages, 4 figures, epl style (.cls-file included), to appear in Europhys. Lett. (http://www.edpsciences.org/epl