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Compound flooding is a type of flood event caused by multiple flood drivers. The associated risk has usually been assessed using statistics-based analyses or hydrodynamics-based numerical models. This study proposes a compound flood (CF) risk assessment (CFRA) framework for coastal regions in the contiguous United States (CONUS). In this framework, a large-scale river model is coupled with a global ocean reanalysis dataset to (a) evaluate the CF exposure related to the coastal backwater effects on river basins, and (b) generate spatially distributed data for analyzing the CF hazard using a bivariate statistical model of river discharge and storm surge. The two kinds of risk are also combined to achieve a holistic understanding of the continental-scale CF risk. The estimated CF risk shows remarkable inter- and intra-basin variabilities along the CONUS coast with more variabilities in the CF hazard over the US west and Gulf coastal basins. Different risk assessment methods present significantly different patterns in a few key regions such as the San Francisco Bay area, the lower Mississippi River, and Puget Sound. Our results highlight the need to weigh different CF risk measures and avoid using single statistics-based or hydrodynamics-based CFRAs. Uncertainty sources in these CFRAs include the use of gauge observations, which cannot account for the flow physics or resolve the spatial variability of risks, and underestimations of the flood extremes and the dependence of CF drivers in large-scale models, highlighting the importance of understanding the CF risks for developing a more robust CFRA. [ABSTRACT FROM AUTHOR]

There is a growing body of economic literature focusing on the negative health effect of air pollution. This paper performs a data-driven analysis of 844 economic publications on air pollution and health in the last three decades. We provide a novel way to visualize the research patterns and features, including the numerical analysis, collaboration network analysis at macro-meso-micro levels, keyword co-occurrence network analysis, and co-citation connection analysis. Additionally, the comparison with the topic dendrogram in environmental science is supplemented to seek the potential research direction. The results reveal that the entire field is now experiencing the rapid development. United States has not only published the largest number of articles, but has also established the most extensive collaborations with other countries. Besides, there have developed a couple of stable cooperative teams consisting of the leading authors. Research topics are gradually leaning toward the developing countries, and research contents are turning to psychological health. More types of air pollutants are worthy of analysis in the future. [ABSTRACT FROM AUTHOR]

Certain diseases have strong comorbidity and co-occurrence with others. Understanding disease–disease associations can potentially increase awareness among healthcare providers of co-occurring conditions and facilitate earlier diagnosis, prevention and treatment of patients. In this study, we utilized the valuable and large The Guideline Advantage (TGA) longitudinal electronic health record dataset from 70 outpatient clinics across the United States to investigate potential disease–disease associations. Specifically, the most prevalent 50 disease diagnoses were manually identified from 165,732 unique patients. To investigate the co-occurrence or dependency associations among the 50 diseases, the categorical disease terms were first mapped into numerical vectors based on disease co-occurrence frequency in individual patients using the Word2Vec approach. Then the novel and interesting disease association clusters were identified using correlation and clustering analyses in the numerical space. Moreover, the distribution of time delay (Δt) between pair-wise strongly associated diseases (correlation coefficients ≥ 0.5) were calculated to show the dependency among the diseases. The results can indicate the risk of disease comorbidity and complications, and facilitate disease prevention and optimal treatment decision-making. [ABSTRACT FROM AUTHOR]

This study characterizes precipitation error propagation through a distributed hydrological model based on the river basins across the contiguous United States (CONUS), to better understand the relationship between errors in precipitation inputs and simulated discharge (i.e., P-Q error relationship). The NLDAS-2 precipitation and its simulated discharge are used as the reference to compare with TMPA-3B42 V7, TMPA-3B42RT V7, Stage IV, CPC-U, MERRA-2, and MSWEPV2.2 for 1548 well-gauged river basins. The relative errors in multiple conventional precipitation products and their corresponding discharges are analyzed for the period of 2002-13. The results reveal positive linear P-Q error relationships at annual and monthly time scales, and the stronger linearity for larger temporal accumulations. Precipitation errors can be doubled in simulated annual accumulated discharge. Moreover, precipitation errors are strongly dampened in basins characterized by temperate and continental climate regimes, particularly for peak discharges, showing highly nonlinear relationships. Radar-based precipitation product consistently shows dampening effects on error propagation through discharge simulations at different accumulation time scales compared to the other precipitation products. Although basin size and topography also influence the P-Q error relationship and propagation of precipitation errors, their roles depend largely on precipitation products, seasons, and climate regimes. [ABSTRACT FROM AUTHOR]

The aim of our study is to evaluate the current practice patterns of radiology report release into electronic patient portals. A survey to assess details of radiology report release was distributed to members of The Association of Administrators in Academic Radiology across the United States. Numerical analysis was used to calculate the frequencies and percentages for the clinical site, frequency and pattern of patient portal use were calculated. Statistical analysis determined the percentages and frequencies for the clinical site, frequency and pattern of patient portal use, as well as statistical differences. A total of 31 (response rate = 28%, 31/108) at least partially completed surveys were received. Most (29/31, 94%) sites reported having a patient portal available with 80% (12/15) reporting < 50% patient utilization. There were no significant (p > 0.05) geographical differences noted in percentage utilization. Seventy-eight percent (21/27) of sites reported some form of automatic radiology report release into their portal. Mean delay was 4 days (range 0–7) from report completion to portal release. No correlation (r = 2) was seen between percentage of patient utilization of portals and timing of radiology report release. Most academic centers across the country have patient portals, however, most of these centers report less than 50% utilization of the portals by patients. While variability in radiology report release in patient portals was noted, the majority (78%) of academic medical centers have some form of automatic report release with average delay of 4 days between report completion to portal release. • Most academic centers have patient portals (94% in our study), although 4 out of 5 institutions report less than 50% of their patients use them. • The majority of our respondents have some form of automatic report release to their portals. • Average lag between report completion to portal release is 4 days (range 0-7 days), although this may be miscalculated due to our small sample size. [ABSTRACT FROM AUTHOR]

Fire-code inspection and compliance are among the highest priorities for fire-inspection agencies to reduce the loss of life and property that can result from fire incidents. Requirements for code compliance and inspection vary throughout towns and states within the United States, and building owners who violate these codes can be penalized via fines and mandated compliance measures. To the best of our knowledge, no previous study has investigated the strategic behavior of players in a fire-code inspection process. This paper fills the gap by presenting the game-theoretic approach to modeling building owners' behaviors with respect to fire-code compliance and the inspection strategies of fire-inspection agencies. Both a decentralized model (sequential game in which the fire-inspection agency moves first) and a centralized model (simultaneous game controlled by one central decision maker) are developed to identify the best inspection strategies for the agency and the best compliance strategies for the building owner. This study provides prescriptive insights that can enable policymakers to improve fire-code compliance and inspection by identifying the conditions that motivate the players to participate positively in the inspection and compliance processes. Numerical sensitivity analyses of the equilibrium strategies and the expected losses of the players are provided, along with a comparison of the results between the decentralized and centralized models. [ABSTRACT FROM AUTHOR]

• Solid oxide fuel cell system integrated with hybrid desiccant cooling is proposed. • Numerical analysis of two system were performed at three climatic conditions. • System optimization for design and operational strategy is achieved. • System without burner at load following mode has the highest electrical efficiency. • System with burner at load following mode has the highest total efficiency. Solid oxide fuel cell systems are advantageous in distributed power generation and are commonly utilized in residential buildings. However, since commercialized small-scale solid oxide fuel cells generally produce hot water using high-temperature exhaust gas, it is difficult to utilize thermal energy in high-temperature areas and during the summer. The exhaust heat from the solid oxide fuel cell system can be effectively utilized by integration with the hybrid desiccant cooling system. In this study, a numerical model of a solid oxide fuel cell system integrated with a hybrid desiccant cooling system has been developed to determine the optimal system configuration and operating strategy. As for the Hot-dry, Hot-humid, and Mixed-humid, which are representative climatic conditions of summer in the United States, were selected. The system model has been simulated at a period of the highest electrical demand in a year with each climate. The solid oxide fuel cell-hybrid desiccant cooling system model has been simulated to compare the system efficiency at 4 case. The simulation results show that the solid oxide fuel cell-hybrid desiccant cooling system without a burner has the highest total efficiency of 77.7 % and the highest total coefficient of performance of 1.528 under electric load following operation. This study can provide the basic insight to establish the parametric analysis and control strategy in integrating the solid oxide fuel cell system and the desiccant cooling system. [ABSTRACT FROM AUTHOR]

We investigate the impact of delay announcements on the coordination within hospital networks using a combination of empirical observations and numerical experiments. We offer empirical evidence that suggests that patients take delay information into account when choosing emergency service providers and that such information can help increase coordination in the network, leading to improvements in the performance of the network, as measured by emergency department wait times. Our numerical results indicate that the level of coordination that can be achieved is limited by the patients' sensitivity to waiting, the load of the system, the heterogeneity among hospitals, and, importantly, the method hospitals use to estimate delays. We show that delay estimators that are based on historical averages may cause oscillation in the system and lead to higher average wait times when patients are sensitive to delay. We provide empirical evidence that suggests that such oscillations occur in hospital networks in the United States. This paper was accepted by Gad Allon, operations management. [ABSTRACT FROM AUTHOR]

The article presents commentary on the report "Did Risk-Based Capital Allocate Bank Credit and Cause a 'Credit Crunch' in the United States?" by Allen N. Berger and Gregory F. Udell included within the issue, addressing the causes of U.S. commercial bank credit reallocations in the 1990s. An in-depth analysis of the numerical calculations included within the report is provided, highlighting the comprehensive nature of the data set provided by the authors. Broader questions are also raised regarding the implications and policy evaluations of the underlying decisions leading to the "credit crunch" problem.

A dynamic pre-positioning problem is proposed to efficiently respond to victims' need for relief supplies under uncertain and dynamic demand in humanitarian relief. The problem is formulated as a multi-stage stochastic programming model that considers pre-positioning with the dynamic procurement and return decisions about relief supplies over a time horizon. To validate the advantages of dynamic pre-positioning, three additional pre-positioning strategies are presented: pre-positioning with one-time procurement and without returns, pre-positioning with one-time procurement and returns, and pre-positioning with dynamic procurement and without returns. Using data from real-world disasters in the United States in the Emergency Events Database, we present a numerical analysis to study the applicability of the proposed models. We develop a sample average approximation approach to solving the proposed model in large-scale cases. Our main contribution is that we integrate dynamic procurement and return strategies into pre-positioning to decrease both costs and shortage risks in uncertain and dynamic contexts. The results illustrate that dynamic pre-positioning outperforms the other three strategies in cost savings. It also indicates that a higher return price is particularly helpful for decreasing unmet demand. The proposed models can help relief agencies evaluate and choose the solutions that will have the greatest overall effectiveness in the context of different relief practices. • A multi-stage stochastic programming model is proposed for dynamic pre-positioning. • Return is integrated and formulated as a dynamic decision. • Sample average approximation is designed for large-scale cases. • Storm, flood and wildfire data is collected from EM-DAT database for numerical analysis. [ABSTRACT FROM AUTHOR]

The empirical test suggests that the log-return series of stock price in US market reject the normal distribution and admit instead a subclass of the asymmetric distribution. In this paper, we investigate the stock loan problem under the assumption that the return of stock follows the finite moment log-stable process (FMLS). In this case, the pricing model of stock loan can be described by a space-fractional partial differential equation with time-varying free boundary condition. Firstly, a penalty term is introduced to change the original problem to be defined on a fixed domain, and then a fully-implicit difference scheme has been developed. Secondly, based on the fully-implicit scheme, we prove that the stock loan value generated by the penalty method cannot fall below the value obtained when the stock loan is exercised early. Thirdly, the numerical experiments are carried out to demonstrate differences of stock loan model under the FMLS and the standard normal distribution. Optimal redemption strategy of stock loan has been achieved. Furthermore the impact of key parameters in our model on the stock loan evaluation are analyzed, and some reasonable explanation are given. [ABSTRACT FROM AUTHOR]

It is well known that the majority of buoy measurements are located around the US coast and along some Europeans countries. The lack of long-term and densely spaced in situ measurements in the Southern Hemisphere in general, and the South Atlantic in particular, hinders several investigations due to the lack of detailed metocean information. Here, we present an effort to overcome this limitation, with a dense network of buoys along the Brazilian coast, equipped with several meteorological and oceanographic sensors. Out of ten currently operational buoys, three are employed to present the main characteristics of waves in the Southern part of the network. For the first time, sensor characteristics and settings are described, as well as the methods applied to the raw wave data. Statistics and distributions of wave parameters, swell propagating events, comparison with a numerical model and altimeters and a discussion about the occurrence of freak waves are presented. [ABSTRACT FROM AUTHOR]

A two-stage setting for determining subsidies and tuitions in a public university context is developed where fixed costs introduce an efficiency-enhancing role for taxpayer-financed appropriations. The optimal subsidy per enrollment is shown to be proportional to students’ maximum net willingness to pay. This result extends a well-known result associated with Ramsey pricing to include endogenous appropriations to public higher education. Realistic restrictions are imposed on the subsidy structure, and scenarios for determining tuitions are addressed and illustrated numerically, using budget data for the University of Iowa and the University of Michigan. [ABSTRACT FROM AUTHOR]

An effort has been made to improve quantitative understanding of beach morphology and stone structural damage progression and to develop a simple and robust model that is suited for engineering applications. The effort for the last 10 years has produced the cross-shore numerical model CSHORE, which is presently limited to the case of alongshore uniformity and uniform cohesionless sediment including sand, gravel, and stone. CSHORE consists of the following components: a combined wave and current model based on time-averaged continuity, cross-shore and longshore momentum, wave energy or action, and roller energy equations; a sediment transport model for suspended load and bed load; a permeable layer model to account for porous flow and energy dissipation; formulas for irregular wave run-up; a probabilistic model for an intermittently wet and dry zone on impermeable and permeable bottoms for the purpose of predicting wave overwash of a dune and armor layer damage progression, respectively; a drag force model for piles interacting with waves and sand dunes; and a dike erosion model by irregular wave action. The theories and formulas in CSHORE, which were published piece by piece, are assembled in this special issue to highlight the progress and shortcomings as well as to integrate coastal hydrodynamics, sediments, and structures for practical applications. [ABSTRACT FROM AUTHOR]

Background: Few studies have examined weight transitions in contemporary multi-ethnic populations spanning early childhood through adulthood despite the ability of such research to inform obesity prevention, control, and disparities reduction. Methods and Results: We characterized the ages at which African American, Caucasian, and Mexican American populations transitioned to overweight and obesity using contemporary and nationally representative cross-sectional National Health and Nutrition Examination Survey data (n = 21,220; aged 2–80 years). Age-, sex-, and race/ethnic-specific one-year net transition probabilities between body mass index-classified normal weight, overweight, and obesity were estimated using calibrated and validated Markov-type models that accommodated complex sampling. At age two, the obesity prevalence ranged from 7.3% in Caucasian males to 16.1% in Mexican American males. For all populations, estimated one-year overweight to obesity net transition probabilities peaked at age two and were highest for Mexican American males and African American females, for whom a net 12.3% (95% CI: 7.6%-17.0%) and 11.9% (95% CI: 8.5%-15.3%) of the overweight populations transitioned to obesity by age three, respectively. However, extrapolation to the 2010 U.S. population demonstrated that Mexican American males were the only population for whom net increases in obesity peaked during early childhood; age-specific net increases in obesity were approximately constant through the second decade of life for African Americans and Mexican American females and peaked at age 20 for Caucasians. Conclusions: African American and Mexican American populations shoulder elevated rates of many obesity-associated chronic diseases and disparities in early transitions to obesity could further increase these inequalities if left unaddressed. [ABSTRACT FROM AUTHOR]

As the number of combined-cycle units increases, efficient modeling approaches for these units play important roles for independent system operators (ISOs). Based on various combinations of combustion turbines (CTs) and steam turbines (STs), the combined-cycle unit could work at different configurations (modes) with different efficiencies. In this paper, we propose an edge-based formulation for the combined-cycle units in the unit commitment problem to improve the accuracy and effectiveness of current modeling approaches. Our formulation can 1) clearly describe the transition processes among different configurations so as to satisfy the ISO financial offer submission requirements and (2) capture physical constraints of each turbine, including the exact min-up/down time and time dependent startup cost, in the combined-cycle units so as to increase the operational flexibility while ensuring system feasibility. This model fits well with the current U.S. deregulated electricity market. The final numerical studies show that our approaches perform better than the current configuration-based modeling approach. [ABSTRACT FROM AUTHOR]

The rapid increase of wealth inequality in the past few decades is one of the most disturbing social and economic issues of our time. Studying its origin and underlying mechanisms is essential for policy aiming to control and even reverse this trend. In that context, controlling the distribution of income, using income tax or other macroeconomic policy instruments, is generally perceived as effective for regulating the wealth distribution. We provide a theoretical tool, based on the realistic modeling of wealth inequality dynamics, to describe the effects of personal savings and income distribution on wealth inequality. Our theoretical approach incorporates coupled equations, solved using iterated maps to model the dynamics of wealth and income inequality. Notably, using the appropriate historical parameter values we were able to capture the historical dynamics of wealth inequality in the United States during the course of the 20th century. It is found that the effect of personal savings on wealth inequality is substantial, and its major decrease in the past 30 years can be associated with the current wealth inequality surge. In addition, the effect of increasing income tax, though naturally contributing to lowering income inequality, might contribute to a mild increase in wealth inequality and vice versa. Plausible changes in income tax are found to have an insignificant effect on wealth inequality, in practice. In addition, controlling the income inequality, by progressive taxation, for example, is found to have a very small effect on wealth inequality in the short run. The results imply, therefore, that controlling income inequality is an impractical tool for regulating wealth inequality. [ABSTRACT FROM AUTHOR]

The United States pediatric vaccine market is examined using Bertrand–Edgeworth–Chamberlin price competition. The proposed game captures interactions between symmetric, capacity-constrained manufacturers in a differentiated, single-product market with linear demand. Results indicate that a unique pure strategy equilibrium exists in the case where the capacities of the manufacturers are at their extreme. For the capacity region where no pure strategy equilibrium exists, there exists a mixed strategy equilibrium where the distribution function, its support, and the expected profit of the manufacturers are characterized. Three game instances are introduced to model the United States pediatric vaccine market. In each instance, the manufacturers are assumed to have equal capacity in producing vaccines. Vaccines are differentiated based upon the number of reported adverse medical events for that vaccine. Using a game-theoretic model, equilibrium prices are computed for each monovalent vaccine. Results indicate that the equilibrium prices for monovalent vaccines are lower than the federal contract prices. The numerical results provide both a lower and upper bound for the vaccine equilibrium prices in the public sector, based on the capacity of the vaccine manufacturers. Results illustrate the importance of several model parameters such as market demand and vaccine adverse events on the equilibrium prices. Supplementary materials are available for this article. Go to the publisher’s online edition ofIIE Transactionsfor datasets, additional tables, detailed proofs, etc. [ABSTRACT FROM AUTHOR]

Radial and azimuthal anisotropy in seismicwave speeds have long been observed using surface waves and are believed to be controlled by deformation within the Earth's crust and uppermost mantle. Although radial and azimuthal anisotropy reflect important aspects of anisotropic media, few studies have tried to interpret them jointly. We describe a method of inversion that interprets simultaneous observations of radial and azimuthal anisotropy under the assumption of a hexagonally symmetric elastic tensor with a tilted symmetry axis defined by dip and strike angles. We show that observations of radial anisotropy and the 2Ψ component of azimuthal anisotropy for Rayleigh waves obtained using USArray data in the western United States can be fit well under this assumption. Our inferences occur within the framework of a Bayesian Monte Carlo inversion, which yields a posterior distribution that reflects both variances of and covariances between all model variables, and divide into theoretical and observational results. Principal theoretical results include the following: (1) There are two distinct groups of models (Group 1, Group 2) in the posterior distribution in which the strike angle of anisotropy in the crust (defined by the intersection of the foliation plane with Earth's surface) is approximately orthogonal between the two sets. (2) The Rayleigh wave fast axis directions are orthogonal to the strike angle in the geologically preferred group of models in which anisotropy is strongly non-elliptical. (3) The estimated dip angle may be interpreted in two ways: as a measure of the actual dip of the foliation of anisotropic material within the crust, or as a proxy for another non-geometric variable, most likely a measure of the deviation from hexagonal symmetry of the medium. The principal observational results include the following: (1) Inherent S-wave anisotropy (γ ) is fairly homogeneous vertically across the crust, on average, and spatially across the western United States. (2) Averaging over the region of study and in depth, γ in the crust is approximately 4.1 ± 2 per cent. γ in the crust is approximately the same in the two groups of models. (3) Dip angles in the two groups of models show similar spatial variability and display geological coherence. (4) Tilting the symmetry axis of an anisotropic medium produces apparent radial and apparent azimuthal anisotropies that are both smaller in amplitude than the inherent anisotropy of the medium, which means that most previous studies have probably underestimated the strength of anisotropy. [ABSTRACT FROM AUTHOR]

In the last two decades, stormwater chamber products have become popular in the United States and other countries for managing stormwater. These products are typically arch-shaped and light-weight for efficient transportation, handling, and field installation. Despite the popularization of the products, currently there is a lack of rational analysis/design methods for these structures. Also, with little effort to establish industry standards, these chambers come with various raw materials, wall designs, and cross-sectional shapes. In this paper, a software package was used to perform a series of two-dimensional numerical simulations of both single and multiple chamber systems installed in the ground. Based on the simulation results, several key issues related to stormwater chamber structure were discussed, such as the optimum cross-sectional geometry, failure modes, and chamber spacing. Computer simulation results were also viewed in light of observations made during recent field loading tests. Main conclusions reached in the study are that (1) the arch-shaped chamber structures, having either semicircular or elliptical cross-sectional shape, are capable of sustaining a high level of external loading by distributing the stresses to the surrounding soil columns; and (2) the foot region of the chamber appears to be critical and needs special attention. [ABSTRACT FROM AUTHOR]

We propose a general likelihood evaluation method for nonlinear non-Gaussian state-space models using the simulation-based method of efficient importance sampling. We minimize the simulation effort by replacing some key steps of the likelihood estimation procedure by numerical integration. We refer to this method as numerically accelerated importance sampling. We show that the likelihood function for models with a high-dimensional state vector and a low-dimensional signal can be evaluated more efficiently using the new method. We report many efficiency gains in an extensive Monte Carlo study as well as in an empirical application using a stochastic volatility model for U.S. stock returns with multiple volatility factors. Supplementary materials for this article are available online. [ABSTRACT FROM PUBLISHER]

Over the past several years, increased rates of mortgage foreclosures in the United States have had significant impacts on economies around the world. As part of the societal response to this problem, nonprofit community development corporations acquire foreclosed properties in troubled neighborhoods and redevelop them to maintain stability. This paper addresses a decision problem faced by these organizations on what types of properties to acquire given limited available resources. We develop dynamic and stochastic programming models to assist such organizations in choosing foreclosed properties for acquisition and redevelopment, taking into account uncertain market conditions that change over time. We first analytically study a dynamic programming model under some special cases, and then seek insights for the general stochastic model through a multistage stochastic programming formulation and its numerical analysis. Although our analysis is based on a problem in the United States with potential implications for the global economy, our research is applicable to non-U.S. government actors at the local and regional level as well. [ABSTRACT FROM AUTHOR]

Abstract: Simulations of the Simmel effect are performed for agents in a scale-free social network. The social hierarchy of an agent is determined by the degree of his/her node. Particular features, once selected by a highly connected agent, become common in lower classes but soon fall out of fashion and become extinct. Numerical results reflect the dynamics of frequency of American babies’ names in 1880–2011. [Copyright &y& Elsevier]

Because of the threat that Hurricane Irene (2011) posed to the United States, supplemental observations were collected for assimilation into operational numerical models in the hope of improving forecasts of the storm. Synoptic surveillance aircraft equipped with dropwindsondes were deployed twice daily over a 5-day period, and supplemental rawinsondes were launched from all upper-air sites in the continental United States east of the Rocky Mountains at 0600 and 1800 UTC, marking an unprecedented magnitude of coverage of special rawinsondes at the time. The impact of assimilating the supplemental observations on National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) model track forecasts of Irene was evaluated over the period that these observations were collected. The GFS track forecasts possessed small errors even in the absence of the supplemental observations, providing little room for improvement on average. The assimilation of the combined dropwindsonde and supplemental rawinsonde data provided small but statistically significant improvements in the 42-60-h range for GFS forecasts initialized at 0600 and 1800 UTC. The primary improvement from the dropwindsonde data was also within this time range, with an average improvement of 20% for 48-h forecasts. The rawinsonde data mostly improved the forecasts beyond 3 days by modest amounts. Both sets of observations provided small, additive improvements to the average cross-track errors. Investigations of individual forecasts identified corrections to the model analyses of the Atlantic subtropical ridge and an upstream midlatitude short-wave trough over the contiguous United States due to the assimilation of the extra data. [ABSTRACT FROM AUTHOR]

Abstract: The United States ITER Project Office (USIPO) is responsible for fabrication of the Central Solenoid (CS) for International Thermonuclear Experimental Reactor (ITER). The CS Insert (CSI) project should provide a verification of the conductor performance in relevant conditions of temperature, field, currents and mechanical strain. The US IPO will build the CSI that will be tested at the Central Solenoid Model Coil (CSMC) Test Facility at JAEA, Naka. One of the design goals of the CSI is to assure that the properties of the conductor near the median plane are measured accurately. Since Nb3Sn is strain sensitive and electromagnetic forces generate a significant strain that increases the current sharing temperature (T cs), we need to design the Insert in such a way that the most strained conductor near the median plane would still have the lowest T cs of all the rest of the conductor in the Insert. The difference between thermal contraction of the jacket and spacer material allows controlling axial distribution of the coil radial deformation. Numerical analysis of the CSI was performed using stainless steel, titanium and invar spacer material variants. Distribution of the T cs was obtained from numerical results in the form similar to one proposed for ITER. [Copyright &y& Elsevier]

Spanish engineering firm Intecsa-lnarsa was part of the Design Team for the SR 99 Bored Tunnel in the USA, the largest in diameter (17,56 m) thus far. The numerical analysis purpose is defining a ground treatment to accommodate a hyperbaric intervention. The analysis was focused on varying air pressure conditions within the half-filled excavation chamber to get a minimum value that guarantees a good equilibrium concerning (1) water ingresses, (2) ground movements and (3) tunnel face stability. [ABSTRACT FROM AUTHOR]

Earthquake loss estimation systems in the US, for example HAZUS (Hazard in US), have been established based on sufficient damage records for the purpose of prevention and efficient response to earthquake hazards; however, in Korea, insufficient data sets of earthquakes and damage records are currently available. In this study, the earthquake damages to pipelines in Korea using the pipeline repair rate (RR) recommended in HAZUS was reevaluated with the degree of confidence when RR is used without modification for the damage estimation of pipelines in Korea. The numerical analyses using a commercial finite element model, ABAQUS, were carried out to compare stresses and strains mobilized in both brittle and ductile pipelines constructed by the design criteria and construction specifications of both Korea and the US. These pipelines were embedded in dense sand overlying three different in situ soils (clay, sand, and gravel) subjected to earthquake excitations with peak ground accelerations (PGAs) of 0.2 to 1.2 g and 1994 Northridge and 1999 Chi-Chi earthquake loadings. The numerical results show that differences in the stress and strain rates are less than 10 %. This implies that RR in HAZUS can be used for earthquake damage estimation of pipelines with a 90 % confidence level in Korea. [ABSTRACT FROM AUTHOR]

Highlights: [•] NWP irradiance models are evaluated at 34 sites in Canada, Europe, and the US. [•] Global NWP models tend to outperform mesoscale models in all locations tested. [•] The skill of the best forecast models is ∼50% when compared to persistence. [Copyright &y& Elsevier]

Unprecedented levels of US subprime mortgage defaults precipitated a severe global financial crisis in late 2008, plunging much of the industrialized world into a deep recession. However, the fundamental reasons for why US mortgages defaulted at such spectacular rates remain largely unknown. This paper presents empirical evidence showing that the ability to perform basic mathematical calculations is negatively associated with the propensity to default on one's mortgage. We measure several aspects of financial literacy and cognitive ability in a survey of subprime mortgage borrowers who took out loans in 2006 and 2007, and match them to objective, detailed administrative data on mortgage characteristics and payment histories. The relationship between numerical ability and mortgage default is robust to controlling for a broad set of sociodemographic variables, and is not driven by other aspects of cognitive ability. We find no support for the hypothesis that numerical ability impacts mortgage outcomes through the choice of the mortgage contract. Rather, our results suggest that individuals with limited numerical ability default on their mortgage due to behavior unrelated to the initial choice of their mortgage. [ABSTRACT FROM AUTHOR]

Surfactants may affect soil structure differently depending upon the soil or the quality of rainfall or irrigation water. This study examined whether the water-stable aggregation of 11 wettable soils was affected by surfactants and the water in which the soils were sieved. The study also examined whether the wettable soils' water drop penetration time (WDPT) was affected by surfactants, water drop quality, and elapsed time since the surfactants were applied. Two nonionic surfactants and a surfactant-free water control were sprayed (by misting) upon air-dry soil, then WDPT was measured 1 and 72 h thereafter. Subsequently, this treated soil was slowly wetted with an aerosol to its water content at a matric potential of −3 kPa, then immediately sieved for 600 s in water that contained either appreciable or few electrolytes. Water-stable aggregation, quantified as mean weight diameter (MWD), varied widely among soils, ranging from 0.10 to 1.36 mm. The MWDs were affected (at p = 0.06) by surfactant treatments, depending upon the soil but not sieving water quality. Surfactants affected the MWD of an Adkins loamy sand and Feltham sand, two of the three coarsest-textured soils. Although WDPTs never exceeded 5 s, depending upon the soil WDPTs were affected by surfactant treatments but not by water drop quality. After surfactant application, WDPTs generally decreased with time for three soils but increased with time for one soil. Findings suggested that surfactants interacted (1) with clay mineralogy to affect MWD and (2) with soluble calcium to affect WDPT for certain soils. Surfactant treatments but not water quality affected both MWD and WDPT for some but not all of 11 wettable, US soils. Published 2012. This article is a US Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

This paper presents a new method for solving mathematical programs with equilibrium constraints. The approach uses a transformation of the original problem via Schur's decomposition coupled with two separate formulations for modeling related absolute value functions. The first formulation, based on SOS1 variables, when solved to optimality will provide a global solution to the MPEC. The second, penalty-based formulation is used to heuristically obtain local solutions to large-scale MPECs. The advantage of these methods over disjunctive constraints for solving MPECs is that computational time is much lower, which is corroborated by numerical examples. Finally, an application of the method to an MPEC representing the United States natural gas market is given. [ABSTRACT FROM AUTHOR]

Development and contributions to computational fluid dynamics (CFD) at the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) during the period from 1947 to the present are reviewed in five categories: numerical methods, physical modeling, CFD codes development, CFD validation and engineering applications, and multidisciplinary design optimization. Some representative results in applications to aero and propulsion systems are included to illustrate the developed capabilities. GRC has a long history of investing resources to develop these key subject matters, with an interest in a wide range of applications, primarily focusing on propulsion-related technologies and concepts. The evolved CFD capabilities have enabled simulations of complex three-dimensional flow fields for engine components and integrated configurations, as illustrated in this article. This article is intended to give a useful, albeit noncomplete, overview into GRC's work in CFD. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this paper is to analyse and describe the topological properties of the institutional and national collaboration network from the profiles extracted from Google Scholar Citations (GSC). 19,912 unique profiles with “co-authors” were obtained from a web crawl performed in March 2012. Several statistical and network analysis techniques were used to map and analyse these collaboration relationships at the country and institution level. Results show that The United States dominates the world scientific map and that every research institution is grouped by national, geographical and cultural criteria. A clustering phenomenon based on the self-similarity and fractal properties of scale-free networks is also observed. We conclude that GSC is a suitable tool for collaboration studies only at macro level between countries and institutions. [Copyright &y& Elsevier]

We compare the regulatory environment for the maximum technical interest rate of life insurance contracts in four European countries and the United States. In Germany, Austria and Switzerland, the maximum rate is driven by a long-term rolling average of government bond yields and is adjusted by the regulator. In the U.S., corporate bond yields are used and the regulator is not directly involved in setting the maximum rate. The regime implemented in the United Kingdom is unique: instead of a rules-based 'one-size-fits-all' approach, the maximum rate is determined by a company-specific principle-based method. We provide a comparative analysis of the different systems and conduct a numerical analysis to investigate how the maximum rate will develop under predefined interest rate scenarios. The discussion is highly relevant in light of Solvency II, a regime that may fundamentally change regulation of the maximum technical interest rate. [ABSTRACT FROM AUTHOR]

Abstract: The present work aims at studying the local to regional atmospheric pollution transport and transformation processes over Bulgaria and at tracking and characterizing the main pathways and processes that lead to atmospheric composition formation in the region. The US EPA Models-3 system is chosen as a modeling tool. As the NCEP Global Analysis Data with 1 degree resolution is used as meteorological background, the MM5 and CMAQ nesting capabilities are applied for downscaling the simulations to a 9 km resolution over Balkans and 3 km over Bulgaria. The TNO emission inventory is used as emission input. Special pre-processing procedures are created for introducing temporal profiles and speciation of the emissions. The study is based on a large number of numerical simulations carried out day by day for the years 2000–2007 and four emission scenarios—with all the emissions and with biogenic emissions, emissions from energetics and road transport excluded. Results from the numerical simulations concerning the main features of the atmospheric composition in Bulgaria and the contribution of the different emission categories are demonstrated in the paper. Some results from the CMAQ “Integrated Process Rate Analysis” are also given. [Copyright &y& Elsevier]

Abstract: An inverse method for liner acoustic impedance eduction in a duct is presented. The determination of adjoint equations allows to make explicit the directional derivatives of the objective function, needed by the search algorithm. Direct and adjoint system of equations are spatially discretized by a discontinuous Galerkin scheme. The propagation model and the eduction process are successfully validated on NASA benchmark data extracted from literature, in a no-flow configuration. Objective functions written in terms of acoustic pressure and acoustic velocity are considered successively. Special attention is given to the possibilities offered by the method, such as multiparameter identification, with the study of a non-homogeneous liner. Convergence history of the process is also examined, revealing interesting properties for the velocity-based objective function compared to the pressure-based objective function. In further developments, the method is planned to be used with acoustic velocity fields obtained by laser doppler velocimetry. [Copyright &y& Elsevier]

Non-recurrent traffic congestion due to incidents, highway construction zones, and special events has contributed up to 60% of the total freeway corridor delay in the United States. Under most scenarios, if proper diversion plans can be implemented in time, motorists can circumvent the congested segments and best use the available corridor capacity. Nevertheless, before the implementation of any detour strategy, traffic managers must ensure the resulting benefits, because implementing those advanced control strategies usually demand substantial amount of resources and manpower. This study, proposed in response to such needs, presents a detour decision methodology for urban freeway non-recurrent congestion management, based on the results of extensive simulation experiments and operational guidelines from highway agencies. The proposed model offers a reliable and effective tool for responsible traffic management personnel to make consistent detour decisions in response to a detected incident. Numerical results clearly indicate that a timely and well-justified detour operation can yield substantial benefits to both the driving population and the entire community. [ABSTRACT FROM AUTHOR]

Abstract: Circulation in typical fjords is characterized by a shallow brackish layer at the surface over a deep long and narrow saltwater column. This surface layer is responsible for the outflow of water from the fjord and is important for flushing of the basin and water quality maintenance. The vertical structure of circulation and transport is known to be easily disrupted, and we postulate that the stability of fjordal circulation may also be vulnerable to impacts from anthropogenic alterations, such as floating structures, which could constrict the mixing and transport in the upper layers of the water column. First, using simplified fjord geometry and a three-dimensional finite volume coastal ocean model (FVCOM), a baseline examination of tidally averaged current profiles in basins with and without sills is presented. The response, varying from a partially mixed estuary regime to classical fjord conditions matches many fjord-like basins such as those in Puget Sound, Washington. The effect of surface obstruction on tidally averaged currents and residence times was then examined by incorporation of a narrow block in the surface layer of the model across the width of the simplified fjord channel such that normal velocity in the horizontal direction was forced to zero. This block approximated the presence of a floating bridge and was further tested using the geometry of Hood Canal, a fjordal sub-basin with a sill in Puget Sound. The results show that tidally averaged mean outflow under the influence of such a constraint at the water surface could be reduced significantly. In the case of Hood Canal, preliminary results indicate that the presence of the floating bridge might have increased the residence times in the basin by 8–13%, which could be an important factor affecting water quality. [Copyright &y& Elsevier]