Adaptive Tracking of a Single-Rigid-Body Character in Various Environments

Since the introduction of DeepMimic [Peng et al. 2018], subsequent research has focused on expanding the repertoire of simulated motions across various scenarios. In this study, we propose an alternative approach for this goal, a deep reinforcement learning method based on the simulation of a single-rigid-body character. Using the centroidal dynamics model (CDM) to express the full-body character as a single rigid body (SRB) and training a policy to track a reference motion, we can obtain a policy that is capable of adapting to various unobserved environmental changes and controller transitions without requiring any additional learning. Due to the reduced dimension of state and action space, the learning process is sample-efficient. The final full-body motion is kinematically generated in a physically plausible way, based on the state of the simulated SRB character. The SRB simulation is formulated as a quadratic programming (QP) problem, and the policy outputs an action that allows the SRB character to follow the reference motion. We demonstrate that our policy, efficiently trained within 30 minutes on an ultraportable laptop, has the ability to cope with environments that have not been experienced during learning, such as running on uneven terrain or pushing a box, and transitions between learned policies, without any additional learning

A National Study of Social Media, Television, Radio, and Internet Usage of Adults by Sexual Orientation and Smoking Status: Implications for Campaign Design

Background: Smoking rates among lesbian, gay, and bisexual (LGB) people significantly exceed that of heterosexuals. Media interventions are an important part of tobacco control efforts, but limited information is available on LGB people’s media use. Methods: A nationally representative sample of 12,900 U.S. adults completed an online questionnaire assessing media use, smoking status, and demographic information. Multivariable logistic regression was used to assess relationships between media use with sexual orientation and smoking status. Results: A total of 590 (4.6%) respondents identified as LGB, of which 29% were smokers. Regardless of sexual orientation and smoking status, the Internet was the most popular media channel used, followed by television and radio. LGB respondents had significantly greater odds of having accounts on social media websites, accessing Facebook daily, and being a frequent Internet user, compared to heterosexual respondents. Similar media use was found between smokers and non-smokers, but smokers had greater odds of being frequent television viewers and frequent Internet users, compared to non-smokers. Conclusions: Compared to heterosexuals, LGB respondents reported greater use of the Internet, especially social media. Media campaigns targeting LGB populations can maximize reach by utilizing social media alongside traditional media channels

Holographic investigation of solid propellant combustion in a two-dimensional motor.

This investigation continued the development of a method for obtaining high quality holograms of the combustion products from metallized solid rocket motor propellants burned in a two-dimensional motor to provide a cross-flow environment. The use of borosilicate side plates as a motor casing allowed good quality holograms to be obtained. With the present two-dimensional motor method there were upper limits of combustion pressure and weight percentage of aluminum where holograms could not be obtained because of excessive smoke opacity.http://archive.org/details/holographicinves00leeyF04611-84-X-0001Major, Republic of Korea Air ForceApproved for public release; distribution is unlimited

Doctoral thesis recital (baritone)

textLecture: Lori Laitman, Selected songs and the stylistic analysis -- Holocaust ; The throwback ; Money ; Dreaming / Lori LaitmanMusi

Toward seamless multiscale computations

textEfficient and robust numerical simulation of multiscale problems encountered in science and engineering is a formidable challenge. Full resolution of multiscale problems using direct numerical simulations requires enormous amounts of computational time and resources. This thesis develops seamless multiscale methods for ordinary and partial differential equations under the framework of the heterogeneous multiscale method (HMM). The first part of the thesis is devoted to the development of seamless multiscale integrators for ordinary differential equations. The first method, which we call backward-forward HMM (BFHMM), uses splitting and on-the-fly filtering techniques to capture slow variables of highly oscillatory problems without any a priori information. The second method, denoted by variable step size HMM (VSHMM), as the name implies, uses variable mesoscopic step sizes for the unperturbed equation, which gives computational efficiency and higher accuracy. VSHMM can be applied to dissipative problems as well as highly oscillatory problems, while BFHMM has some difficulties when applied to the dissipative case. The effect of variable time stepping is analyzed and the two methods are tested numerically. Multi-spatial problems and numerical methods are discussed in the second part. Seamless heterogeneous multiscale methods (SHMM) for partial differential equations, especially the parabolic case without scale separation are proposed. SHMM is developed first for the multiscale heat equation with a continuum of scales in the diffusion coefficient. This seamless method uses a hierarchy of local grids to capture effects from each scale and uses filtering in Fourier space to impose an artificial scale gap. SHMM is then applied to advection enhanced diffusion problems under incompressible turbulent velocity fields.Mathematic