6,515 research outputs found

    Forward and Backward Continuation Ratio Models for Ordinal Response Variables

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    There are different types of continuation ratio (CR) models for ordinal response variables. The different model equations, corresponding parameterizations, and nonequivalent results are confusing. The purpose of this study is to introduce different types of forward and backward CR models, demonstrate how to implement these models using Stata, and compare the results using data from the Educational Longitudinal Study of 2002 (ELS:2002)

    Analysis of Translation Errors in English-Chinese Translation Practice

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    This paper adopts the error score method to study the English-Chinese translation quality of MTI English translation majors from five dimensions: fidelity, fluency, terminology translation, style and cultural acceptance, taking the Chinese translation practice texts of students majoring in MTI English translation as the research object. The results show that students are more likely to make mistakes in terms of fluency and terminology when translating from Chinese to English, and students have difficulties in conveying the style of the original text when translating from Chinese to English. The results propose some methods of avoiding translation errors and improving the quality of translation teaching

    A Deep Dive into Blockchain Selfish Mining

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    This paper studies a fundamental problem regarding the security of blockchain on how the existence of multiple misbehaving pools influences the profitability of selfish mining. Each selfish miner maintains a private chain and makes it public opportunistically for the purpose of acquiring more rewards incommensurate to his Hashrate. We establish a novel Markov chain model to characterize all the state transitions of public and private chains. The minimum requirement of Hashrate together with the minimum delay of being profitable is derived in close-form. The former reduces to 21.48% with the symmetric selfish miners, while their competition with asymmetric Hashrates puts forward a higher requirement of the profitable threshold. The profitable delay increases with the decrease of the Hashrate of selfish miners, making the mining pools more cautious on performing selfish mining.Comment: 6 pages, 13 figure

    Shape Modeling of a Concentric-tube Continuum Robot

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    Mechanics Parameter Optimization and Evaluation of Curtain Grouting Material in Deep, Water-Rich Karst Tunnels

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    Mud and water often gush suddenly during the construction process of deep buried karst tunnels, which may cause serious accidents and result in major economic losses. Accordingly, for tunnels buried in deep rich water districts, discovering how to effectively control water gushing and ensure the stability of surrounding rock has great influence on the safety of engineering construction. The case study in this paper simulates the water-rich section of Dou-mo tunnel from Shanghai to Kunming of China. Numerical analysis was used to simulate the construction of the curtain grouting section and to evaluate the effects of the various curtain grouting parameters. The optimal grouting parameters were selected and then evaluated by applying them to the grouting method. The results show that (1) the grouting effect is the most notable one when the thickness of the grouting circle is outside the 4 m range of the tunnel contour. (2) In the same circle, the grouting quantity of the same ring is presented as a wave form. Therefore the number of the same ring grouting holes should reduce and increase the distance between the adjacent grouting holes appropriately to reduce the number of grouting holes and speed up the grouting progress

    Bjorken variable and scale dependence of quark transport coefficient in semi-inclusive lepton-production of hadron off nuclei

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    Nuclear modification of hadron production in deep inelastic lepton-nucleus scattering can be applied to study the parton propagation mechanism in cold nuclear matter. By means of the analytic parameterization of quenching weight based on BDMPS formalism with the target nuclear geometry effect, the leading-order computations for hadron multiplicity ratios are performed with comparison to the HERMES charged pions production data on the quarks hadronization occurring outside the nucleus. The relation is discovered between quark transport coefficient and the measurable kinematic variables in deep inelastic scattering. Four models are proposed on the quark transport coefficient. The constant model, the power-law model and the double power-law model can be ruled out because of the experimental fact that the transverse momentum broadening increases as a function of the photon virtuality Q2Q^2. The quark transport coefficient is determined as a function of the Bjorken variable xx and scale Q2Q^2. The trend of quark transport coefficient in respect of Bjorken variable xx and scale Q2Q^2 is qualitatively in partial agreement with HERMES experimental data on transverse momentum broadening. It is hoped that our effort is conducive to understanding of jet quenching phenomenon in relativistic heavy ion collisions
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