Data-Driven Approach to Simulating Realistic Human Joint Constraints

Modeling realistic human joint limits is important for applications involving physical human-robot interaction. However, setting appropriate human joint limits is challenging because it is pose-dependent: the range of joint motion varies depending on the positions of other bones. The paper introduces a new technique to accurately simulate human joint limits in physics simulation. We propose to learn an implicit equation to represent the boundary of valid human joint configurations from real human data. The function in the implicit equation is represented by a fully connected neural network whose gradients can be efficiently computed via back-propagation. Using gradients, we can efficiently enforce realistic human joint limits through constraint forces in a physics engine or as constraints in an optimization problem.Comment: To appear at ICRA 2018; 6 pages, 9 figures; for associated video, see https://youtu.be/wzkoE7wCbu

Analysis of bank efficiency of Chinese commercial banks and the effects of institutional changes on bank efficiency.

This study contributes to the well-established efficiency literature with respect to transition economies and developing counties. Although bank efficiency has been a popular research area in both developed countries and less developed nations, it has been scarce in China mainly due to the lack of data. This study is considered as the first study that comprehensively investigates bank performance using multiple methodologies of financial ratio analysis and stochastic frontier analysis for the period of 1995-2005. The effects of a variety of governance changes have also been differentiated in order to providing policy recommendations for the on-going banking reform. Meanwhile, this study has addressed a number of methodological issues and has developed a more comprehensive stochastic distance function model by combining advantages of existing models, approaches, methods and procedures. Having experienced fundamental banking reforms for more than a quarter of century, the Chinese banking System has stridden towards a modem banking System with significant improvements in profitability, capitalization, and assets quality. Despite of these observed improvements, the banking system is still associated with relatively low profitability and capitalization, poor asset quality, and less liquidity, when benchmarking to 7 selected international renowned banks. One of the most impressive progresses has been the significant decrease in both outstanding NPLs balance and NPL ratio. However, it has noticed that the threat of NPLs problem to the economy as a whole remains unsolved. This study has rationalized economic foundations for the banking reform in China being the principal-agent theory and the budgetary constraint theory. The performance of Chinese banks has been improved and the estimated effîciency level is consistently at 75% in terms of technical efficiency, cost efficiency and profit efficiency. Employing the method of Berger et al. (2005), this study has jointly analyzed the static, selection and dynamic effects of governance changes. Joint-stock ownership has resulted in outstanding performance, while state ownership has been associated with low technical efficiency and profit efficiency but high cost efficiency. Foreign banks are more profit efficient but less cost and technical efficient (static effects). Foreign investors have rationally made their investment decisions by selecting more cost and technical efficient domestic banks, while less profitable domestic banks have been chosen for going public in line with government intension of reforming the unprofitable SOCBs (selection effects). Attracting foreign strategic investors and encouraging banks going public are two major partial privatization strategies, which have been generally proved as effective reform measures. The former tends to have positive impacts on technical efficiency and cost efficiency, while significant short-term gains in profit efficiency have faded in the long-term. The expected profit advantage of foreign ownership seems to take an even longer time to be realized. Going public strategy has resulted in performance improvement in the long-term after short-term losses (dynamic effects). We can not form a conclusion on whether the reform has succeeded, while what we can conclude is the reform is on the track with right direction. It is important to construct good corporate governance, but it is more important to ensure the good governance functioning. If those deep-rooted problems, such as government intervention and NPL problem, can not be dealt with properly in the near future, the chance of success is very small. Thus, our policy recommendations include consolidating up-to-date reform achievements, improving bank's managerial and operational skills, and reducing state's share in banks to lessen government interventions. Estimated efficiency is found to be sensitive to the differences in the definitions of outputs and inputs, especially in the presence of high level of NPLs. The income-based model is superior to the earning assets-based model in the estimation of technical efficiency. Similarly, profit efficiency appears to be more appropriate performance measures over cost efficiency. However, we suggest the use of multiple models and measures to reveal more valuable information. Moreover, in estimating cost function and alternative profit function, market average input prices are found to be more appropriate than banks' specific input prices

Hyperon Electromagnetic Properties in Two-Flavor Chiral Perturbation Theory

The pion mass dependence of hyperon electromagnetic properties is determined using two-flavor heavy baryon chiral perturbation theory. Specifically we compute chiral corrections to the charge radii, magnetic moments, and magnetic radii of the spin one-half hyperons, as well as the charge radii, magnetic moments, magnetic radii, electric quadrupole moments, and quadrupole radii of the spin three-half hyperons. Results for the nucleon and delta are also included. Efficacy of the two-flavor theory is investigated by analyzing the role played by virtual kaons. For the electromagnetic properties of spin one-half hyperons, kaon loop contributions are shown to be well described by terms analytic in the pion mass squared. Similarly kaon contributions to the magnetic moments of spin three-half hyperons are well described in the two-flavor theory. The remaining electromagnetic properties of spin three-half resonances can be described in two-flavor chiral perturbation theory, however, this description fails just beyond the physical pion mass. For the case of experimentally known hyperon magnetic moments and charge radii, we demonstrate that chiral corrections are under reasonable control, in contrast to the behavior of these observables in the three-flavor chiral expansion. The formulae we derive are ideal for performing the pion mass extrapolation of lattice QCD data obtained at the physical strange quark mass.Comment: 29 pages, 7 figures, v3: published versio

Social reference: Aggregating online usage of scientific literature in CiteULike for clustering academic resources

Citation-based methods have been widely studied and employed for clustering academic resources and mapping science. Although effective, these methods suffer from citation delay. In this study, we extend reference and citation analysis to a broader notion from social perspective. We coin the term "social reference" to refer to the references of literatures in social academic web environment. We propose clustering methods using social reference information from CiteULike. We experiment for journal clustering and author clustering using social reference and compare with citation-based methods. Our experiments indicate: first, social reference implies connections among literatures which are as effective as citation in clustering academic resources; second, in practical settings, social reference-based clustering methods are not as effective as citation-based ones due to the sparseness of social reference data, but they can outperform in clustering new resources that have few citation. © 2011 Authors