Efficient dynamic simulation for multiple chain robotic mechanisms

An efficient O(mN) algorithm for dynamic simulation of simple closed-chain robotic mechanisms is presented, where m is the number of chains, and N is the number of degrees of freedom for each chain. It is based on computation of the operational space inertia matrix (6 x 6) for each chain as seen by the body, load, or object. Also, computation of the chain dynamics, when opened at one end, is required, and the most efficient algorithm is used for this purpose. Parallel implementation of the dynamics for each chain results in an O(N) + O(log sub 2 m+1) algorithm

Ejection Forces and Friction Coefficients from Injection Molding Experiments Using Rapid Tooling Inserts

Experiments have been performed with injection mold inserts made using solid freeform fabrication processes in an effort to further study such applications for economic production of small quantities of parts. Static friction coefficients were determined for HDPE and HIPS against P-20 steel, sintered LaserForm ST-100, and stereolithography SL 5170 using the ASTM D 1894 standard. Injection mold inserts were constructed of the same three materials and were used to inject cylindrical parts using HDPE and HIPS. Ejection forces were measured, and a model was used to calculate ejection forces and apparent coefficients of static friction. Statistical analyses were used to determine the effects of packing time, cooling time and packing pressure on ejection force for the three insert types. This paper compares experimental and calculated ejection forces, compares standard friction test results to calculated apparent coefficients of friction, summarizes the statistical results, and comments on the feasibility of using rapid tooled inserts for injection molding.Mechanical Engineerin

Bostonia. Volume 1

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Ophelia and the Feminine Construct

In Shakespeare\u27s celebrated tragic masterpiece, Hamlet, one of the most controversial and seminal characters, Ophelia, continues to have a heavy influence on contemporary culture today in some unexpected ways. Her prevalence in mainstream media––including film, literature, drama, and music homages––validates not only her importance now but also reimagines and reinforces her parallel importance at the time of her debut in 1603. Her association with global teenage culture, suicide, and mental illness, puts her in the unique position of being heralded, generation after generation, as an icon of depression in female youth. This can be both positive and negative, as those young girls can either be inspired by Ophelia\u27s struggles and identify with them toward a journey to recovery, or the moguls in mass media can commercialize that identification to rope in that teenage demographic. Either way, Ophelia\u27s presence in global culture is fundamentally both fascinating and problematic, and it is the attempt of this research to explore and elucidate that spectrum, as articulated by the feminine construct of the 21st Century

Collaborative Strategies that would Minimize Interruption in Work Output in a Human Resources Development Department during an Acquisition

The problem of this study was to identify collaborative strategies that would minimize interruption in work output in a Human Resources Development department during an acquisition

Technology Use in Rural Appalachia: A Pilot Study of the Implications for Pediatric Behavioral Health

Technology is a promising means for increasing rural individuals’ access to behavioral healthcare. However, the range of technology use in rural areas is currently unknown. The aims of this study were to examine the use of technology in rural areas, the relationship between technology use and willingness to access pediatric mental health services via videoconferencing, and this relationship within the context of other critical variables linked to service uptake. Data were collected at 2 pediatric primary care clinics. While no significant relationship was found between technology use and willingness to use videoconferencing, a significant relationship emerged between previous service seeking and willingness to use videoconferencing. These findings indicate the need for more research examining other variables’ relationships to willingness to seek help via technology, such as general help-seeking attitudes, unfamiliarity with videoconferencing services, or other variables included in previously established models of technology adoption

Tunneling and nonlinear transport in a vertically coupled GaAs/AlGaAs double quantum wire system

We report low-dimensional tunneling in an independently contacted vertically coupled quantum wire system. This nanostructure is fabricated in a high quality GaAs/AlGaAs parallel double quantum well heterostructure. Using a novel flip chip technique to align top and bottom split gates to form low-dimensional constrictions in each of the independently contacted quantum wells we explicitly control the subband occupation of the individual wires. In addition to the expected 2D-2D tunneling results, we have found additional tunneling features that are related to the 1D quantum wires.Comment: 4 pages, 3 figures, submitted to APL Minor revision

Photo-z Performance for Precision Cosmology II : Empirical Verification

The success of future large scale weak lensing surveys will critically depend on the accurate estimation of photometric redshifts of very large samples of galaxies. This in turn depends on both the quality of the photometric data and the photo-z estimators. In a previous study, (Bordoloi et al. 2010) we focussed primarily on the impact of photometric quality on photo-z estimates and on the development of novel techniques to construct the N(z) of tomographic bins at the high level of precision required for precision cosmology, as well as the correction of issues such as imprecise corrections for Galactic reddening. We used the same set of templates to generate the simulated photometry as were then used in the photo-z code, thereby removing any effects of "template error". In this work we now include the effects of "template error" by generating simulated photometric data set from actual COSMOS photometry. We use the trick of simulating redder photometry of galaxies at higher redshifts by using a bluer set of passbands on low z galaxies with known redshifts. We find that "template error" is a rather small factor in photo-z performance, at the photometric precision and filter complement expected for all-sky surveys. With only a small sub-set of training galaxies with spectroscopic redshifts, it is in principle possible to construct tomographic redshift bins whose mean redshift is known, from photo-z alone, to the required accuracy of 0.002(1+z).Comment: 7 pages, 5 figures, accepted for publication in MNRA

Transplantation in children

Kidney transplantation in very young children, less than 2 years of age, has usually failed, mainly because of difficulties maintaining these patients on hemodialysis long enough to permit retransplantation after loss of the original graft. Liver replacement in the very young child has been associated with a higher frequency of vascular and biliary obstruction than in the older child, due to the small size of these structures. Such accidents have contributed to unsatisfactory results with biliary atresia. Transplantation of kidney or liver into older children has been more successful than transplantation of these organs into adults. Related or cadaveric kidney transplantation in the child has been followed by at least a 60 per cent patient survival for 6 to 13 years and a very acceptable quality of life. Liver replacement for diseases other than biliary atresia has been followed by a 56 per cent 1 year survival rate, and two children have survived for more than 5 years