9 Matching Results

Search Results

Advanced search parameters have been applied.

Compliant membranes for the development of MEMS dual-backplate capacitive microphone using the SUMMiT V fabrication process.

Description: The objective of this project is the investigation of compliant membranes for the development of a MicroElectrical Mechanical Systems (MEMS) microphone using the Sandia Ultraplanar, Multilevel MEMS Technology (SUMMiT V) fabrication process. The microphone is a dual-backplate capacitive microphone utilizing electrostatic force feedback. The microphone consists of a diaphragm and two porous backplates, one on either side of the diaphragm. This forms a capacitor between the diaphragm and each backplate. As the incident pressure deflects the diaphragm, the value of each capacitor will change, thus resulting in an electrical output. Feedback may be used in this device by applying a voltage between the diaphragm and the backplates to balance the incident pressure keeping the diaphragm stationary. The SUMMiT V fabrication process is unique in that it can meet the fabrication requirements of this project. All five layers of polysilicon are used in the fabrication of this device. The SUMMiT V process has been optimized to provide low-stress mechanical layers that are ideal for the construction of the microphone's diaphragm. The use of chemical mechanical polishing in the SUMMiT V process results in extremely flat structural layers and uniform spacing between the layers, both of which are critical to the successful fabrication of the MEMS microphone. The MEMS capacitive microphone was fabricated at Sandia National Laboratories and post-processed, packaged, and tested at the University of Florida. The microphone demonstrates a flat frequency response, a linear response up to the designed limit, and a sensitivity that is close to the designed value. Future work will focus on characterization of additional devices, extending the frequency response measurements, and investigating the use of other types of interface circuitry.
Date: November 1, 2005
Creator: Martin, David (University of Florida, Gainesville, FL)
Partner: UNT Libraries Government Documents Department

Infant-Caregiver Attachment and Separation: Single vs. Multiple Caregivers

Description: This study investigates (1) whether infants cared for by a single caregiver exhibit more attachment behaviors than do infants cared for by multiple caregivers and (2) whether sex differences are found in these behaviors. Twenty-six Black infants, nine to twenty-three months of age, in a day-care center, were observed during one brief low-stress separation from a caregiver. Data were taken using six indices of attachment: maintaining proximity, visual regard, touching, protesting, seeking proximity, and greeting. Where subjected to a two-way analysis of variance, the obtained results showed no significant differences in the effects of the two types of care. However, visual regard and greeting behaviors were observed significantly more frequently in females than in males.
Date: December 1975
Creator: Martin, David Wayne
Partner: UNT Libraries

A Cryogenic RF Material Testing Facility at SLAC

Description: The authors have developed an X-band SRF testing system using a high-Q copper cavity with an interchangeable flat bottom for the testing of different materials. By measuring the Q of the cavity, the system is capable to characterize the quenching magnetic field of the superconducting samples at different power level and temperature, as well as the surface resistivity. This paper presents the most recent development of the system and testing results.
Date: June 22, 2012
Creator: Guo, Jiquan; Martin, David; Tantawi, Sami; Yoneda, Charles & /SLAC
Partner: UNT Libraries Government Documents Department

Development of an Integrated Performance Model for TRISO-Coated Gas Reactor Particle Fuel

Description: The success of gas reactors depends upon the safety and quality of the coated particle fuel. The understanding and evaluation of this fuel requires development of an integrated mechanistic fuel performance model that fully describes the mechanical and physico-chemical behavior of the fuel particle under irradiation. Such a model, called PARFUME (PARticle Fuel ModEl), is being developed at the Idaho National Engineering and Environmental Laboratory. PARFUME is based on multi-dimensional finite element modeling of TRISO-coated gas reactor fuel. The goal is to represent all potential failure mechanisms and to incorporate the statistical nature of the fuel. The model is currently focused on carbide, oxide nd oxycarbide uranium fuel kernels, while the coating layers are the classical IPyC/SiC/OPyC. This paper reviews the current status of the mechanical aspects of the model and presents results of calculations for irradiations from the New Production Modular High Temperature Gas Reactor program.
Date: May 1, 2005
Creator: Petti, David Andrew; Miller, Gregory Kent; Martin, David George & Maki, John Thomas
Partner: UNT Libraries Government Documents Department


Description: During this final year of the Pacific Northwest Regional Collaboratory we focused significantly on continuing the relationship between technical teams and government end-users. The main theme of the year was integration. This took the form of data integration via our web portal and integration of our technologies with the end users. The PNWRC's technical portfolio is based on EOS strategies, and focuses on 'applications of national priority: water management, invasive species, coastal management and ecological forecasting.' The products of our technical approaches have been well received by the community of focused end-users. The objective this year was to broaden that community and develop external support to continue and operationalize product development.
Date: April 1, 2008
Creator: Tagestad, Jerry D.; Bolte, John; Guzy, Michael; Woodruff, Dana L.; Humes, Karen; Walden, Von et al.
Partner: UNT Libraries Government Documents Department

Recent Advances in VisIt: AMR Streamlines and Query-Driven Visualization

Description: Adaptive Mesh Refinement (AMR) is a highly effective method for simulations spanning a large range of spatiotemporal scales such as those encountered in astrophysical simulations. Combining research in novel AMR visualization algorithms and basic infrastructure work, the Department of Energy's (DOEs) Science Discovery through Advanced Computing (SciDAC) Visualization and Analytics Center for Enabling Technologies (VACET) has extended VisIt, an open source visualization tool that can handle AMR data without converting it to alternate representations. This paper focuses on two recent advances in the development of VisIt. First, we have developed streamline computation methods that properly handle multi-domain data sets and utilize effectively multiple processors on parallel machines. Furthermore, we are working on streamline calculation methods that consider an AMR hierarchy and detect transitions from a lower resolution patch into a finer patch and improve interpolation at level boundaries. Second, we focus on visualization of large-scale particle data sets. By integrating the DOE Scientific Data Management (SDM) Center's FastBit indexing technology into VisIt, we are able to reduce particle counts effectively by thresholding and by loading only those particles from disk that satisfy the thresholding criteria. Furthermore, using FastBit it becomes possible to compute parallel coordinate views efficiently, thus facilitating interactive data exploration of massive particle data sets.
Date: November 12, 2009
Creator: Weber, Gunther; Ahern, Sean; Bethel, Wes; Borovikov, Sergey; Childs, Hank; Deines, Eduard et al.
Partner: UNT Libraries Government Documents Department