Modelling shell and oscillation mark formation during continuous casting via explicit incorporation of slag infiltration

The development of reliable numerical models is vital to improve the quality of continuously cast products and to increase the productivity of the casting machine. In order to provide accurate predictions, these models must include detailed descriptions of the physical phenomena occurring inside the mould, such as metal flow, heat transfer and solidification. However, these topics are often treated separately during modelling due to their complexity. This has a negative impact on the accuracy of the predictions. To address this issue, a numerical model capable of coupling the flow dynamics with both the heat transfer to the mould walls and solidification has been developed. The 2‐dimenional model is based on a commercial CFD code that solves the Navier‐Stokes Equations coupled with a Volume of Fluid interface tracking technique for the multiphase system slag‐steel‐air under transient conditions within a conventional slab mould. The use of an extremely fine mesh in the meniscus region (~50 μm) allows, for the first time, the explicit calculation of liquid slag infiltration into the shell‐mould gap. Heat transfer through the solid mould faces and mould oscillation were also included in the model to provide a more realistic representation of the process. The model developed was tested in two case studies. In the first case, the predicted values were compared to prior numerical models and laboratory experiments directed to casting of conventional slabs. Excellent agreement was found for characteristics such as slag film development and heat flux variations during mould oscillation. Furthermore, predicted values for shell thickness, consumption and heat flux were also found to be in good agreement with plant measurements. The findings of this case study provided improved, fundamental understanding of the mechanisms involved in slag infiltration and solidification inside the mould and how these affect key process parameters, such as powder consumption and shell growth. The second case study consisted of a sensitivity study, where casting conditions (e.g. casting speed, mould cooling, steel/slag properties and oscillation settings) were varied in the simulations to determine their effect on both powder consumption and the formation of defects. The simulations predicted the initial formation of typical casting defects known as oscillation marks, without the aid of any external data fitting. The key result drawn from the sensitivity study was the determination of simple rules for the calculation of consumption, heat flux and defect formation as a function of the casting conditions. This opens the possibility of using the model as a diagnostic tool and for process optimisation

The Globalization of Trade and Democracy, 1870-2000

We study whether international trade fosters democracy. The likely endogeneity between democracy and trade is addressed via the gravity model of trade, allowing us to obtain a measure of natural openness. This serves as our instrumental variable for actual trade openness à la Frankel and Romer (1999). We use this powerful instrument to obtain estimates of the causal impact of openness on democratization. A positive impact of openness on democracy is apparent from about 1895 onwards. Late nineteenth century trade globalization may have helped generate the "first wave" of democratization. Between 1920 and 1938 countries more exposed to international trade were less likely to become authoritarian. Finally, our post-World War II results suggest that a one standard deviation increase in trade with other countries could bring countries like Indonesia, Russia or Venezuela to be as democratic as the US, Great Britain or France. We also see some variation in the impact of openness by region and note that commodity exporters and petroleum producers do not seem to become more democratic by exporting more of such items.

Bike Lanes, Not Cars: Mobility and the Legal Fight for Future Los Angeles

In 2015, the City of Los Angeles adopted the controversial Mobility Plan 2035. The Plan restructures city transportation planning by emphasizing alternatives to cars for the next twenty years. Predictably, bike lanes became its most polemic aspect. The Plan envisions dramatic increases in bike lanes throughout car-obsessed Los Angeles. This bike lane increase was challenged in court, with objectors claiming that eliminating car lanes would increase congestion and compromise air quality. These arguments are ironic, since environmental justifications typically motivate bike projects. The Mobility Plan illustrates how law supports and challenges bike lane projects. This Article argues that although this bike lane fight regards inches and miles of road space, the fight is primarily centered on how Angelinos will live in the future. As bike advocates attain popular and policy successes, they must confront legal contests driven by car-centric interests. Los Angeles shows how city planning achievements open a path for bike lane opposition armed with city governance, environmental, transportation, and land use doctrines

Leveraging the Urysohn Lemma of Topology for an Enhanced Binary Classifier

In this article we offer a comprehensive analysis of the Urysohn's classifier in a binary classification context. It utilizes Urysohn's Lemma of Topology to construct separating functions, providing rigorous and adaptable solutions. Numerical experiments demonstrated exceptional performance, with scores ranging from 95% to 100%. Notably, the Urysohn's classifier outperformed CatBoost and KNN in various scenarios. Despite sensitivity to the p-metric parameter, it proved robust and adaptable. The Urysohn's classifier's mathematical rigor and adaptability make it promising for binary classification, with applications in medical diagnosis, fraud detection and cyber security. Future research includes parameter optimization and combining the Urysohn's classifier with other techniques. It offers an elegant and principled approach to classification, ensuring integrity and valuable data insights

Global Migrations and Imagined Citizenship: Examples From Slavery, Chinese Exclusion, and When Questioning Birthright Citizenship

These theoretical approaches motivate this Essay to ask the following about legal citizenship determinations: (a) what is the global movement in persons that leads to the citizenship question?; and (b) what is the imagined community articulated by the legal determination of citizenship? From these questions, a legal inquiry into national identity and citizenship gains historical, global, and cultural perspectives. The next three sections briefly describe the examples of slavery, Dred Scott, and citizenship; Chinese migration to the U.S., Chinese Exclusion measures, and citizenship; and citizenship as seen from a migration experience of U.S.-pull and Mexico-push. For each of the cases their respective sections, Sections II through IV, present these legal citizenship determinations and then identify relevant global migration and imagined community contexts

How sensitive are Latin American exports to Chinese competition in the U.S. market ?

This paper estimates the elasticity of substitution of U.S. imports using detailed trade data over the 1990-2003 period. The authors use a two-stage least squares framework in order to identify the elasticity parameter of interest. The authors use the elasticity estimates to assess the extent to which Latin American and Chinese goods compete in the U.S. market by providing forecasts of how alternative policy scenarios may affect exports to the United States. The analysis considers the following scenarios: (i) currency revaluation in China; (ii) elimination of U.S. tariffs on Latin American exports under a hemispheric free trade agreement; and (iii) the elimination of quotas on apparel and textile exports under the Multi-Fiber Agreement. The findings show that a 20-percent appreciation of the renminbi reduces Chinese exports to the United States by a fifth, although since other regions increase sales to that market (0.5 percent for Latin America), U.S. imports decline by only 1.7 percent. Hemispheric free trade would increase Latin America's exports to the United States by around 3 percent. The removal of the quotas would lead to a sharp increase in Chinese sales to the United States (40 percent), but Latin America would see its share of the U.S. market decline by around 2 percent (2.5 percentage points). China's gains would come mainly at the expense of other regions of the world.Economic Theory&Research,Free Trade,Markets and Market Access,Trade Policy,Debt Markets

Trade War, PPE, and Race

Tariffs on Personal Protective Equipment (PPE), such as face masks and gloves, weaken the American response to COVID. The United States has exacerbated PPE shortages with Section 301 tariffs on these goods, part of a trade war with China. This has a disparate impact felt by minority communities because of a series of health inequity harms. COVID’s racial disparity appears in virus exposure, virus susceptibility, and COVID treatments. This Article makes legal, policy, and race-and-health arguments. Congress has delegated to the United States Trade Representative expansive authority to increase tariffs. This has made PPE supplies casualties of the trade war. In political terms, the Trump administration prioritized increasing tariffs over public health readiness. Regarding race, PPE shortages exemplify the socioeconomic effects of trade policies and add to COVID’s racial disparities

The incidence of graft on developing-country firms

This paper measures the extent to which firms in developing countries are the target of bribes. Using new firm-level survey data from 33 African and Latin American countries, we first show that perceptions adjust slowly tofirms'experience with corrupt officials and hence are an imperfect proxy for the true incidence of graft. We then construct an experience-based index that reflects the probability that a firm will be asked for a bribe in order to complete a specified set of business transactions. On average, African firms are three times as likely to be asked for bribes as are firms in Latin America, although there is substantial variation within each region. Last, we show that graft appears to be more prevalent in countries with excessive regulation and where democracy is weak. In particular, our results suggest that the incidence of graft in Africa would fall by approximately 85 percent if countries in the region had levels of democracy and regulation similar to those that exist in Latin America.Public Sector Corruption&Anticorruption Measures,Corruption&Anitcorruption Law,Crime and Society,E-Business,Access to Finance