Electromagnetic shielding (EMS) requirements become more demanding as isolation requirements exceed 100dB in advanced S-band transceiver designs. Via-hole fences have served such designs well in low temperature cofired ceramic (LTCC) modules when used in 2-3 rows, depending on requirements. Replacing these vias with slots through the full thickness of a tape layer has been modeled and shown to improve isolation. We expand on a technique for replacing these rows of full tape thickness features (FTTF) with a single row of stacked walls which, by sequential punching, can be continuous, providing a solid Faraday cage board element with leak-free seams. We discuss the material incompatibilities and manufacturing considerations that need to be addressed for such structures and show preliminary implementations. We will compare construction of multilayer and single layer designs.
Recent papers have argued for the benefit of a tighter integration of the disciplines of human factors (HF) and human reliability analysis (HRA). While both disciplines are concerned with human performance, HF uses performance data to prescribe optimal human-machine interface (HMI) design, while HRA applies human performance principles and data to model the probabilistic risk of human activities. An overlap between the two disciplines is hindered by the seeming incompatibility of their respective data needs. For example, while HF studies produce data especially about the efficacy of particular system designs, these efficacy data are rarely framed in such a way as to provide the magnitude of the performance effect in terms of human error. While qualitative insights for HRA result from the HF studies, the HF studies often fail to produce data that inform the quantification of human error. In this paper, the author presents a review of the data requirements for HRA and offers suggestions on how to piggyback HRA data collection on existing HF studies. HRA data requirements include specific parameters such as the effect size of the human performance increment or degradation observed and classification of the human performance according to a simple set of performance shaping factors.
Active aerodynamic load control of wind turbine blades has been heavily researched for years by the wind energy research community and shows great promise for reducing turbine fatigue damage. One way to benefit from this technology is to choose to utilize a larger rotor on a turbine tower and drive train to realize increased turbine energy capture while keeping the fatigue damage of critical turbine components at the original levels. To assess this rotor-increase potential, Sandia National Laboratories and FlexSys Inc. performed aero/structural simulations of a 1.5MW wind turbine at mean wind speeds spanning the entire operating range. Moment loads at several critical system locations were post-processed and evaluated for fatigue damage accumulation at each mean wind speed. Combining these fatigue damage estimates with a Rayleigh wind-speed distribution yielded estimates of the total fatigue damage accumulation for the turbine. This simulation procedure was performed for both the turbine baseline system and the turbine system incorporating a rotor equipped with FlexSys active aerodynamic load control devices. The simulation results were post-processed to evaluate the decrease in the blade root flap fatigue damage accumulation provided by the active aero technology. The blade length was increased until the blade root flap fatigue damage accumulation values matched those of the baseline rotor. With the new rotor size determined, the additional energy capture potential was calculated. These analyses resulted in an energy capture increase of 11% for a mean wind speed of 6.5m/s.
Recent advances in nanoparticle inks have enabled inkjet printing of metal traces and interconnects with very low (100-200°C) process temperatures. This has enabled integration of printable electronics such as antennas and radio frequency identification (RFID) tags with polyimide, teflon, PCBs, and other low temperature substrates. We discuss here printing of nanoparticle inks for three dimensional interconnects, and the apparent mechanism of nanoparticle ink conductivity development at these low process temperatures.
This paper describes a set of critical experiments that were done to gather benchmark data on the effects of rhodium in critical systems. Approach-to-critical experiments with arrays of low-enriched water-moderated and -reflected fuel were performed with rhodium foils sandwiched between the fuel pellets in some of the fuel elements. The results of the experiments are compared with results from two Monte Carlo codes using cross sections from ENDF/B-V, ENDF/B-VI, and ENDF/B-VII.
This paper applies a pragmatic interval-based approach to validation of a fire dynamics model involving computational fluid dynamics, combustion, participating-media radiation, and heat transfer. Significant aleatory and epistemic sources of uncertainty exist in the experiments and simulations. The validation comparison of experimental and simulation results, and corresponding criteria and procedures for model affirmation or refutation, take place in "real space" as opposed to "difference space" where subtractive differences between experiments and simulations are assessed. The versatile model validation framework handles difficulties associated with representing and aggregating aleatory and epistemic uncertainties from multiple correlated and uncorrelated source types, including: • experimental variability from multiple repeat experiments • uncertainty of experimental inputs • experimental output measurement uncertainties • uncertainties that arise in data processing and inference from raw simulation and experiment outputs • parameter and model-form uncertainties intrinsic to the model • numerical solution uncertainty from model discretization effects. The framework and procedures of the model validation methodology are here applied to a difficult validation problem involving experimental and predicted calorimeter temperatures in a wind-driven hydrocarbon pool fire.
The significant growth in wind turbine installations in the past few years has fueled new scenarios that envision even larger expansion of U.S. wind electricity generation from the current 1.5% to 20% by 2030. Such goals are achievable and would reduce carbon dioxide emissions and energy dependency on foreign sources. In conjunction with such growth are the enhanced opportunities for manufacturers, developers, and researchers to participate in this renewable energy sector. Ongoing research activities at the National Renewable Energy Laboratory and Sandia National Laboratories will continue to contribute to these opportunities. This paper focuses on describing the current research efforts at Sandia's wind energy department, which are primarily aimed at developing large rotors that are lighter, more reliable and produce more energy.
The significant growth in wind turbine installations in the past few years has fueled new scenarios that envision even larger expansion of U.S. wind electricity generation from the current 1.5% to 20% by 2030. Such goals are achievable and would reduce carbon dioxide emissions and energy dependency on foreign sources. In conjunction with such growth are the enhanced opportunities for manufacturers, developers, and researchers to participate in this renewable energy sector. Ongoing research activities at the National Renewable Energy Laboratory and Sandia National Laboratories will continue to contribute to these opportunities. This paper focuses on describing the current research efforts at Sandia's wind energy department, which are primarily aimed at developing large rotors that are lighter, more reliable and produce more energy.
Grid-based mesh generation methods have been available for many years and can provide a reliable method for meshing arbitrary geometries with hexahedral elements. The principal use for these methods has mostly been limited to biological-type models where topology that may incorporate sharp edges and curve definitions are not critical. While these applications have been effective, robust generation of hexahedral meshes on mechanical models, where the topology is typically of prime importance, impose difficulties that existing grid-based methods have not yet effectively addressed. This work introduces a set of procedures that can be used in resolving the features of a geometric model for grid-based hexahedral mesh generation for mechanical or topology-rich models.