Página 14 dos resultados de 473 itens digitais encontrados em 0.034 segundos
Resultados filtrados por Publicador: Harvard University

Mechanical Behavior of Hydrogels for the Use of Ionic Devices

Li, Jianyu
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
Português
Relevância na Pesquisa
428.99297%
Wearable and implantable devices hold great promise to transform the society by making healthcare continuous, personalized and affordable. They will enable mobile healthcare by monitoring continuously vital signals, and providing various stimulations on the human body. Conventional electronics face a primary challenge: their mechanical and electrical properties mismatch those of tissues. Stretchable electronics provide some remedies to the mechanical mismatch, but any interface between stretchable electronics and tissues must translate an electronic current into an ionic one (and vice versa). Whereas electronics struggle to solve many technical problems, ionic devices solve most of them readily. Hydrogels are the materials of choice for the use of ionic devices. They mix water, mobile ions and polymer networks at molecular scales, and thus intrinsically integrate both ionic conductivity and high stretchability. Hydrogels resemble tissues biologically, mechanically and electrically. Although several ionic devices using hydrogels have been demonstrated, the mechanical behavior of hydrogels represents one of main material constraints: complex chemomechanical interactions, poor mechanical properties and weak adhesion. To this end, this thesis focuses on the mechanical behavior of hydrogels for the use of ionic devices. This thesis first presents theoretical and experimental approaches to characterize chemomechanical interactions of gels. How applied forces...

Architectural Implications of Automatic Parallelization With HELIX-RC

Brownell, Kevin Matthew
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
Português
Relevância na Pesquisa
421.1586%
As classic Dennard process scaling fades into the past, power density concerns have driven modern CPU designs to de-emphasize the pursuit of single-thread performance, focusing instead on increasing the number of cores in a chip. Computing throughput on a modern chip continues to improve, since multiple programs can run in parallel, but the performance of single programs improves only incrementally. Many compilers have been designed to automatically parallelize sequentially written programs by leveraging multiple cores for the same task, thereby enabling continued single-thread performance gains. One such compiler is HELIX, which can increase the performance of a mixture of SPECfp and SPECint benchmarks by 2X on a 6-core Nehalem CPU. Previous approaches to automatically parallelize irregular programs have focused on removing apparent dependences through thread-level speculation, which limits the type of code that can be targeted. In contrast, this dissertation increases the amount of code that can be parallelized by addressing the specific communication demands of that code. The dissertation proposes a special purpose extension of the cache hierarchy, called ring cache, to greatly reduce the perceived communication latency between cores running an automatically parallelized program. This co-design of ring cache and the HELIX compiler...