Generation of planar tensegrity structures through cellular multiplication

Tensegrity structures are frameworks in a stable self-equilibrated prestress state that have been applied in various fields in science and engineering. Research into tensegrity structures has resulted in reliable techniques for their form finding and analysis. However, most techniques address topology and form separately. This paper presents a bio-inspired approach for the combined topology identification and form finding of planar tensegrity structures. Tensegrity structures are generated using tensegrity cells (elementary stable self-stressed units that have been proven to compose any tensegrity structure) according to two multiplication mechanisms: cellular adhesion and fusion. Changes in the dimension of the self-stress space of the structure are found to depend on the number of adhesion and fusion steps conducted as well as on the interaction among the cells composing the system. A methodology for defining a basis of the self-stress space is also provided. Through the definition of the equilibrium shape, the number of nodes and members as well as the number of self-stress states, the cellular multiplication method can integrate design considerations, providing great flexibility and control over the tensegrity structure designed and opening the door to the development of a whole new realm of planar tensegrity systems with controllable characteristics.Comment: 29 pages, 19 figures, to appear at Applied Mathematical Modelin

Final Report Task 16: Archaeological Studies cooperative agreement

From December 1999 to September 2003, the Desert Research Institute (DRI) provided management support and technical services in support of cultural resources management activities for the US Department of Energy (DOE) Yucca Mountain Project (YMP). This effort was conducted as Task 16 of the Cooperative Agreement between the US Department of Energy’s Office of Civilian Radioactive Waste Management (OCRWM) with the University and Community College System of Nevada (UCCSN). The activities conducted under Task 16 were performed on a level-of-effort basis, covering a broad range of support services to implement the cultural resources management program for YMP and to assist the environmental regulatory program and Native American interaction program. In particular, Task 16 covered the following program activities: Preactivity surveys, assessment of effects and mitigative treatments. Perform and document pedestrian cultural resources surveys to identify, characterize, and evaluate cultural resources on lands proposed for surface-disturbing YMP activities, as requested. Develop impact assessments of proposed actions on identified resources. Develop and implement treatment plans and mitigation strategies to protect the values of cultural resources subject to effect, as needed. Periodic monitoring. Monitor known cultural resource localities to assess potential YMP effects, and provide documentation of the monitoring results. Monitoring was conducted to assess cumulative effects of the site characterization phase of the Project, provide a baseline on site condition for any future phases of the Project, and provide a basis for recommendations on future cultural resource protection and management measures. Reporting. Prepare reports for documentation of data collected, cultural resources monitored, analyses conducted, or progress in implementing the PA and supporting program documents, and other reports as requested. These reports include quarterly reports of field activities, technical summary reports, the annual US Department of Interior Federal Archaeology questionnaire, and the annual report of progress in implementing the stipulations of the Programmatic Agreement, among others as requested. Artifact and records curation. Protect and maintain to federal standards collections of artifacts and associated records obtained from studies made by the YMP cultural resources management program. Update and maintain GIS-based electronic databases of cultural resources studies, results, and associated information. Analyses. Conduct artifact analyses appropriate to satisfying the research requirements stipulated by the Programmatic Agreement and the supporting Research Design. Prepare results of these analyses as parts of technical summary reports, and in other professional presentations and publications as appropriate. Native American interaction. Provide support to the Native American interaction program, including site visits, access to examine artifact collections, and consultations, studies, and reporting pertinent to the Native American Graves Protection and Repatriation Act, American Indian Religious Freedom Act, or EO 13007. New programmatic agreement. Support YMP management in planning for development and implementation of a Programmatic Agreement to cover cultural resources management policies at Yucca Mountain after site characterization is completed. EIS support. Provide support for the YMP EIS process, including technical expertise to resolve public comments received during the draft EIS comment period, presence at public hearings as requested, or additional studies or data-gathering activities, as needed. Other support. Support consultations, site visits, monitoring activities, and other communications to BLM, SHPO, and other federal, State, County, and tribal agencies, on issues relating the implementation of stipulations of the PA, as necessary. Progress on these activity areas was reported to the UCCSN on a quarterly and annual basis during the course of performance of Task 16. This final report summarizes accomplishments and deliverables provided to the YMSCO from 1999-2003 under Task 16

Effects of Aquatic and Land Plyometrics on Athletic Performance: A Systematic Review

The purpose of this study was to systematically review literature to determine whether aquatic plyometric training (APT) increases athletic performance compared to land-based plyometric training (LPT). We identified 6 articles from PubMed, CINAHL, MEDLINE, and single-citation matching from January, 1995 through January, 2017 using search words “aquatic plyometric training OR aquatic plyometric OR aquatic plyometrics.” After screening (title, abstract), 6 articles were reviewed for inclusion criteria: (1) full-report/abstract, (2) peer-reviewed RCTs/clinical trials, (3) English language, (4) focused on healthy individuals (free of current, lower-extremity, musculoskeletal injuries) ages 16-30 years, and (6) included strength, power, and/or vertical jump [VJ] dependent variables. Six (of 6) studies met inclusion criteria (LOE, 1b = 6; PEDro score = 6.3±0.3). Reported pooled sample size was 182, mean age 22.46±3.67 (range 17-27). Studies found significant (p\u3e.05) performance increases in the LPT and APT groups, with no significant (p\u3e.05) differences in the amount of performance increase between experimental groups. Results demonstrated both LPT and APT can improve measures of athletic performance; however, neither appears to produce significantly better performance than the other

Design improvement of a pump wear ring labyrinth seal

The investigation was successful in obtaining two improved designs for the impeller wear ring seal of the liquid hydrogen turbopump of interest. A finite difference computer code was extensively used in a parametric computational study in determining a cavity configuration with high flow resistance due to turbulence dissipation. These two designs, along with that currently used, were fabricated and tested. The improved designs were denoted Type O and Type S. The measurements showed that Type O and Type S given 67 and 30 percent reduction in leakage over the current design, respectively. It was found that the number of cavities, the step height and the presence of a small stator groove are quite important design features. Also, the tooth thickness is of some significance. Finally, the tooth height and an additional large cavity cut out from the stator (upstream of the step) are of negligible importance

Investigating the origin of coprolites from three great basin caves

The study of coprolites (mummified feces) is a relatively new endeavor, which enables investigations of the health and diet of ancient people and provides some of the oldest evidence to date for the human habitation in North America (2). In this project, 18 coprolites were examined from archeological digs at three Great Basin caves: the Bonneville Estates Rockshelter (UT), Hidden Cave (NV), and Top of the Terrace Rockshelter (UT). The main objectives were: 1) to verify human origin through the presence of mitochondrial DNA (mtDNA) and 2) assuming human origin, characterize intestinal microflora of Native Americans prior to European contact. Primer sets specific for human mtDNA were employed to obtain products and establish human origin in general and Native American origin specifically (through SNP analysis). Initial microbiological efforts targeted the bacterial genus, Bacteroides, which tend to dominate gut flora in modern humans and thus is considered an ideal indicator for human fecal contamination (1,6). Primers targeting human-associated Bacteroides spp. strains were used in conjunction with human mtDNA results to further verify human origin. A major obstacle in this project, as might be expected, was damage to ancient DNA (aDNA). aDNA from coprolite samples is usually degraded into short fragments due to hydrolytic or oxidative damage, greatly reducing the possibility of long polymerase chain reaction (PCR) amplifications (4). The suggestion is that if large fragments are obtained from PCR, that the sample is most likely contaminated (3). To repair the fragmented aDNA, a technique termed reconstructive polymerization (RP) developed by Golenberg et al. (3) was applied. If these samples are found to be of human origin, it could provide an interesting lens into not only humans, but also the colonization of Western North America and beyond

Cellular morphogenesis of three-dimensional tensegrity structures

The topology and form finding of tensegrity structures have been studied extensively since the introduction of the tensegrity concept. However, most of these studies address topology and form separately, where the former represented a research focus of rigidity theory and graph theory, while the latter attracted the attention of structural engineers. In this paper, a biomimetic approach for the combined topology and form finding of spatial tensegrity systems is introduced. Tensegrity cells, elementary infinitesimally rigid self-stressed structures that have been proven to compose any tensegrity, are used to generate more complex tensegrity structures through the morphogenesis mechanisms of adhesion and fusion. A methodology for constructing a basis to describe the self-stress space is also provided. Through the definition of self-stress, the cellular morphogenesis method can integrate design considerations, such as a desired shape or number of nodes and members, providing great flexibility and control over the tensegrity structure generated.Comment: 31 pages, 17 figure

Analysis of self-equilibrated networks through cellular modeling

Network equilibrium models represent a versatile tool for the analysis of interconnected objects and their relationships. They have been widely employed in both science and engineering to study the behavior of complex systems under various conditions, including external perturbations and damage. In this paper, network equilibrium models are revisited through graph-theory laws and attributes with special focus on systems that can sustain equilibrium in the absence of external perturbations (self-equilibrium). A new approach for the analysis of self-equilibrated networks is proposed; they are modeled as a collection of cells, predefined elementary network units that have been mathematically shown to compose any self-equilibrated network. Consequently, the equilibrium state of complex self-equilibrated systems can be obtained through the study of individual cell equilibria and their interactions. A series of examples that highlight the flexibility of network equilibrium models are included in the paper. The examples attest how the proposed approach, which combines topological as well as geometrical considerations, can be used to decipher the state of complex systems.Comment: 38 pages, 23 figure

Aerodynamic Testing of the Orion Launch Abort Tower Separation with Jettison Motor Jet Interactions

The aerodynamic database for the Orion Launch Abort System (LAS) was developed largely from wind tunnel tests involving powered jet simulations of the rocket exhaust plumes, supported by computational fluid dynamics (CFD) simulations. The LAS contains three solid rocket motors used in various phases of an abort to provide propulsion, steering, and Launch Abort Tower (LAT) jettison from the Crew Module (CM). This paper describes a pair of wind tunnel experiments performed at transonic and supersonic speeds to determine the aerodynamic effects due to proximity and jet interactions during LAT jettison from the CM at the end of an abort. The tests were run using two different scale models at angles of attack from 150deg to 200deg , sideslip angles from -10deg to +10deg , and a range of powered thrust levels from the jettison motors to match various jet simulation parameters with flight values. Separation movements between the CM and LAT included axial and vertical translations as well as relative pitch angle between the two bodies. The paper details aspects of the model design, nozzle scaling methodology, instrumentation, testing procedures, and data reduction. Sample data are shown to highlight trends seen in the results

COMPUTED EFFECT OF RUB-GROOVE SIZE ON STEPPED LABYRINTH SEAL PERFORMANCE

ABSTRACT A numerical study was undertaken to explore the effects of the size of wear-in mb grooves that are typically cut into the abradable land of stepped labyrinth seals. The elliptic form of the 2-D axisymmetric Navier-Stokes equations for compressible turbulent flow were solved. The relationships among the friction coefficient, the leakage Reynolds number, the groove depth and width and the pre-rub radial clearance were examined. It was found that the standard k-s turbulence model and wall functions are effective for computing the friction coefficient and leakage for labyrinth seals with honeycomb land surfaces, both with and without the presence of mb grooves. The so-called rub grooves are the result of labyrinth teeth cutting wear grooves into the abradable surface of the land (stationary housing of the seal). Furthermore, it was found that the case of a small pre-mb tooth radial clearance, a wide rub groove and an intermediate step height is the most sensitive to the presence of a rub groove, with a leakage increase over the no-groove case of about 100 percent and 194 percent for the shallow and deep grooves, respectively. It was also found, for example, that the leakage varied with pre-rub clearance and groove width, in order from lowest to highest leakage, as: (a) small clearance and narrow groove, (b) small clearance and wide groove, (c) large clearance and narrow groove and (d) large clearance and wide groove