Improved Artificial Viscosity in Finite Element Method (FEM) for Hypervelocity Impact Calculations

AbstractIn this paper we develop methods based primarily on the work of Kuropatenko and Wilkins to improve the application of artificial viscosity in 3D finite element method (FEM) codes. The primary goal is to obtain better shock predictions for hypervelocity impacts (HVI) and reduce the need for user calibration. We focus on examining factors such as geometric variability with respect to shock direction, dynamic adaptation to changes in compressibility in the shock front, and anisotropic compression in multi-dimensional formulations. We implement the methods in the Velodyne hydro-structural code and investigate the effects on shock propagation using a series of simple flyer impact test cases which cover a range of system responses including strong and weak shocks. Various initial mesh geometries are utilized to examine mesh effects. Energetic materials using the Ignition and Growth Reactive Burn (IGRB) equation of state (EOS) are also examined due to the rapid change in compressibility and energy density which occurs due to reaction. These rapid changes can lead to insufficient damping in artificial viscosity calculations and thus provide an effective test case. We employ the CTH hydrocode to evaluate baseline shock behavior. The regular, ordered mesh of CTH allows for a consistent and precise application of the artificial viscosity. Direct numerical comparisons are used rather than experimental data to eliminate uncertainty due to factors such as material characterizations, EOS models, and mesh resolution. We compare the CTH results against various FEM artificial viscosity implementations to evaluate performance. It is demonstrated that shock response in FEM codes can be significantly improved by using updated artificial viscosity methods

Nuclear transport models can reproduce charged-particle-inclusive measurements but are not strongly constrained by them

Nuclear transport models are important tools for interpretation of many heavy-ion experiments and are essential in efforts to probe the nuclear equation of state. In order to fulfill these roles, the model predictions should at least agree with observed single-particle-inclusive momentum spectra; however, this agreement has recently been questioned. The present work compares the Vlasov-Uehling-Uhlenbeck model to data for mass-symmetric systems ranging from 12C+12C to 139La+139La, and we find good agreement within experimental uncertainties at 0.4A and 0.8A GeV. For currently available data, these uncertainties are too large to permit effective nucleon-nucleon scattering cross sections in the nuclear medium to be extracted at a useful level of precision

Evaluating Microcounseling Training

An evaluation research design was developed as an attempt to provide a more satisfactory approach to microcounseling training program evaluation. Trainee performance was measured three times during a counseling practicum, with microcounseling training occurring between the second and third observations. Trainee performance was compared to a predetermined standard for counselor behavior. Results were analyzed for both the differences between observations, and the degree of similarity to the model. Counseling behavior of trainees after microcounseling training was significantly different from their behavior prior to the training. After training they were more like the standard. The trainees performed less like the standard after some counseling experience, but before receiving microcounseling training.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66901/2/10.1177_0193841X8300700206.pd

Reimagining Wilmer's Park

Final project for LARC:340 Site Planning and Design Studio (Fall 2022). University of Maryland, College Park.Wilmer’s Park is a “80-acre parcel containing the ruins of a dance hall, motel, ranch house, covered stage, baseball and football fields. As a major stop on the Chitlin Circuit, Wilmer’s Park opened its doors to African-American musicians, entertainers, athletes and fans from the early 1950s through the late 1960s. Arthur Wilmer used his experience and connections developed as the owner of a night club in Washington, D. C. to bring both popular acts and up-and-coming performers to rural Prince George’s County; the bandstand at Wilmer’s Park showcased everyone from Duke Ellington and Otis Redding to the Temptations, Patti La Belle, and a young Stevie Wonder. The former tobacco farm played an important role in exposing emerging musicians to local African Americans during a time of segregation.” The park has been closed for 10+ years and the purpose of this project is to transform Wilmer’s Park for the residents of Brandywine or nearby communities. For this project, students work in teams of three to design a master plan along with an individual detailed site plan. The design program for these plans came from the residents’ comments from community engagement workshops, notes from Councilman Harrison’s interview, important stakeholders, the field trip, and guest lectures. The master plan does not include all 80 acres of the park and often identifies a phasing plan for the entire project.Prince George's County Parks Departmen