2,831 research outputs found

    The Economic Reunification of Korea: A Dynamic General Equilibrium Model

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    This paper constructs a dynamic specific factors model to examine the impact of the economic reunification of North and South Korea. The model is a compromise between the highly stylized neoclassical models of trade found in the theoretical trade literature, and the highly aggregated models used in dynamic macroeconomics. We find that the policies with the biggest effects on aggregate output are changes in government tax and spending rates, particularly spending on infrastructure. In contrast, we find that both skilled and unskilled wages are much more responsive to the particulars of trade policy, particularly openness to intra-Korea trade and intra-Korea labor mobility. The location of production in a fully integrated Korean economy is determined by the location of infrastructure.factor mobility; dynamic general equilibrium; specific-factors; Korea

    3D LiDAR Point Cloud Processing Algorithms

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    In the race for autonomous vehicles and advanced driver assistance systems (ADAS), the automotive industry has energetically pursued research in the area of sensor suites to achieve such technological feats. Commonly used autonomous and ADAS sensor suites include multiples of cameras, radio detection and ranging (RADAR), light detection and ranging (LiDAR), and ultrasonic sensors. Great interest has been generated in the use of LiDAR sensors and the value added in an automotive application. LiDAR sensors can be used to detect and track vehicles, pedestrians, cyclists, and surrounding objects. A LiDAR sensor operates by emitting light amplification by stimulated emission of radiation (LASER) beams and receiving the reflected LASER beam to acquire relevant distance information. LiDAR reflections are organized in a three-dimensional environment known as a point cloud. A major challenge in modern autonomous automotive research is to be able to process the dimensional environmental data in real time. The LiDAR sensor used in this research is the Velodyne HDL 32E, which provides nearly 700,000 data points per second. The large amount of data produced by a LiDAR sensor must be processed in a highly efficient way to be effective. This thesis provides an algorithm to process the LiDAR data from the sensors user datagram protocol (UDP) packet to output geometric shapes that can be further analyzed in a sensor suite or utilized for Bayesian tracking of objects. The algorithm can be divided into three stages: Stage One - UDP packet extraction; Stage Two - data clustering; and Stage Three - shape extraction. Stage One organizes the LiDAR data from a negative to a positive vertical angle during packet extraction so that subsequent steps can fully exploit the programming efficiencies. Stage Two utilizes an adaptive breakpoint detector (ABD) for clustering objects based on a Euclidean distance threshold in the point cloud. Stage Three classifies each cluster into a shape that is either a point, line, L-shape, or a polygon using principal component analysis and shape fitting algorithms that have been modified to take advantage of the pre-organized data from Stage One. The proposed algorithm was written in the C language and the runtime was tested on a two Windows equipped machines where the algorithm completed the processing, on average, sparing 30% of the time between UDP data packets sent from the HDL32E. In comparison to related research, this algorithm performed over seven hundred and thirty-seven times faster

    Commutative Endomorphism Rings of Simple Abelian Varieties over Finite Fields

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    In this thesis we look at simple abelian varieties defined over a finite field k=Fpnk =\mathbb{F}_{p^n} with \End_k(A) commutative. We derive a formula that connects the pp-rank r(A)r(A) with the splitting behavior of pp in E=Q(π)E = \mathbb{Q}(\pi), where π\pi is a root of the characteristic polynomial of the Frobenius endomorphism. We show how this formula can be used to explicitly list all possible splitting behaviors of pp in OE\mathcal{O}_E, and we do so for abelian varieties of dimension less than or equal to four defined over Fp\mathbb{F}_p. We then look for when pp divides [OE:Z[π,πˉ]][\mathcal{O}_E : \mathbb{Z}[\pi, \bar{\pi}]]. This allows us to prove that the endomorphism ring of an absolutely simple abelian surface is maximal at pp when p≥3p \geq 3. We also derive a condition that guarantees that pp divides [OE:Z[π,πˉ]][\mathcal{O}_E: \mathbb{Z}[\pi, \bar{\pi}]]. Last, we explicitly describe the structure of some intermediate subrings of pp-power index between Z[π,πˉ]\mathbb{Z}[\pi, \bar{\pi}] and OE\mathcal{O}_E when AA is an abelian 3-fold with r(A)=1r(A) = 1

    Characteristics of tropical cyclones in the North Atlantic and East Pacific.

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    In this dissertation, I present a series of investigations to expand our understanding of TCs in the East Pacific and North Atlantic basins. First, I developed and applied a climatological tool that quickly and succinctly displays the spread of historical TC tracks for any point in the North Atlantic basin. This tool is useful in all parts of a basin because it is derived from prior storm motion trajectories and summarily captures the historical synoptic and mesoscale steering patterns. It displays the strength of the climatological signal and allow for rapid qualitative comparison between historical TC tracks and NWP models. Second, I have used a robust statistical technique to quantify the relationships between fifteen different metrics of TC activity in nine ocean basins and twelve climate indices of the leading modes of atmospheric and oceanic variability. In a thorough, encyclopedic manner, over 12,000 Spearman rank correlation coefficients were calculated and examined to identify relationships between TCs and their environment. This investigation was not limited to the East Pacific or North Atlantic, and new climatic associations were found between seasonal levels of TC activity and the major climate indices across the nine basins. This information is critical to forecasters, economists, actuaries, energy traders, and societal planners who apply knowledge of levels of TC activity on intraseasonal to interdecadal timescales. The statistics are also valuable to climatologists seeking to understand how regional TC frequency will change as the global climate warms. Third, I have examined the leading intraseasonal mode of atmospheric and oceanic variability, the Madden-Julian Oscillation (MJO), and discovered statistically significant relationships with the frequency of TC genesis, intensification, and landfall over the nine basins. Like the significance of the longer-period oscillations to the frequency of TC activity on intraseasonal and longer timescales, these results are highly relevant to the problem of short-term (one- to two-week) predictability of TC activity. These three investigations demonstrate the utility of historical datasets across a wide range of applications, from short-term forecasting to climate studies. In this way, the results highlighted in this dissertation represent a significant and positive contribution to meteorology. Collectively, they reveal multiple characteristics of TCs in the East Pacific and North Atlantic and provide greater understanding of the complex interactions between TCs and their surrounding larger-scale environment

    Negotiating the Korea-United States Free Trade Agreement

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    Difficult and sensitive issues will command the attention of US and Korean officials as they negotiate a bilateral free trade agreement (FTA). The United States will have to put long-standing US barriers to Korean exports of textiles, apparel, and steel on the table and resolve problems with South Korean access to the US visa waiver program. In turn, South Korea will have to open new opportunities for US goods and services, including autos, beef, and rice. Such a deal will pose a stiff political challenge for Korean officials. However, they will be under pressure in any event to reform their farm programs--either in the context of a final deal in the WTO talks or in response to Chinese initiatives in the region, which Korea will need to match. Both Korea and the United States also have important foreign policy interests in the FTA, particularly enhanced security on the Korean peninsula. South Korea would like the FTA to promote the policy of constructive engagement with North Korea, which the former has been pursuing by extending trade preferences to goods produced in the Kaesong industrial complex in North Korea. However, such a request would put the entire negotiation in jeopardy since the US Congress would reject preferences for the North Korean regime.

    Foreword

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    On Friday, April 14, 2023, the Northwestern Pritzker School of Law community, family, close friends, and colleagues gathered in the Thorne auditorium to celebrate the legacy of Joyce A. Hughes, trailblazer and longtime professor of law. Professor Hughes retired at the end of the 2021–2022 academic year. As part of this celebration, the Northwestern University Law Review presents this special Issue in honor of Professor Hughes and her contributions to legal scholarship and the legal profession. More information about Professor Hughes\u27s legacy can be found here and here

    Modeling Shock Waves Using Exponential Interpolation Functions with the Least-Squares Finite Element Method

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    The hypothesis of this research is that exponential interpolation functions will approximate fluid properties at shock waves with less error than polynomial interpolation functions. Exponential interpolation functions are derived for the purpose of modeling sharp gradients. General equations for conservation of mass, momentum, and energy for an inviscid flow of a perfect gas are converted to finite element equations using the least-squares method. Boundary conditions and a mesh adaptation scheme are also presented. An oblique shock reflection problem is used as a benchmark to determine whether or not exponential interpolation provides any advantages over Lagrange polynomial interpolation. Using exponential interpolation in elements downstream of a shock and having edges coincident with the shock showed a slight reduction in the solution error. However there was very little qualitative difference between solutions using polynomial and exponential interpolation. Regardless of the type of interpolation used, the shocks were smeared and oscillations were present both upstream and downstream of the shock waves. When a mesh adaptation scheme was implemented, exponential elements adjacent to the shock waves became much smaller and the numerical solution diverged. Changing the exponential elements to polynomial elements yielded a convergent solution. There appears to be no significant advantage to using exponential interpolation in comparison to Lagrange polynomial interpolation

    The effect of ethyl cellulose on the properties of short-oil varnishes.

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