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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Physics-based simulation of EM and SM in TSV-based 3D IC structures

Evolution of stresses in through-silicon-vias (TSVs) and in the TSV landing pad due to the stress migration (SM) and electromigration (EM) phenomena are considered. It is shown that an initial stress distribution existing in a TSV depends on its architecture and copper fill technology. We demonstrate that in the case of proper copper annealing the SM-induced redistribution of atoms results in uniform distributions of the hydrostatic stress and concentration of vacancies along each segment. In this case, applied EM stressing generates atom migration that is characterized by kinetics depending on the preexisting equilibrium concentration of vacancies. Stress-induced voiding in TSV is considered. EM induced voiding in TSV landing pad is analyzed in details.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Heating performances of a IC in-blanket ring array

An important limiting factor to the use of ICRF as candidate heating method in a commercial reactor is due to the evanescence of the fast wave in vacuum and in most of the SOL layer, imposing proximity of the launching structure to the plasma boundary and causing, at the highest power level, high RF standing and DC rectified voltages at the plasma periphery, with frequent voltage breakdowns and enhanced local wall loading. In a previous work [1] the concept for an Ion Cyclotron Heating & Current Drive array (and using a different wave guide technology, a Lower Hybrid array) based on the use of periodic ring structure, integrated in the reactor blanket first wall and operating at high input power and low power density, was introduced. Based on the above concept, the heating performance of such array operating on a commercial fusion reactor is estimated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Demonstration and analysis of a 600 V, 10 A, 4H-SiC lateral single RESURF MOSFET for power ICs applications

This paper reports the demonstration of a 600 V 4H-SiC lateral MOSFET with a large current handling capability (10 A). To achieve a high breakdown voltage in a lateral architecture, a REduced SURface Field (RESURF) structure was implemented to alleviate surface electric field crowding. A single RESURF (P-top) design on an N-drift on a 6-in. N+ substrate demonstrated a voltage supporting capability of 120 V/ μ m, resulting in a breakdown voltage of 600 V. The total width of 198 mm for the interdigitated gate fingers was designed to accomplish the high current capability. It turned out that, for relatively low voltage SiC lateral MOSFETs (<600 V), more focus needs to be placed on achieving a low channel, contact, metal, and JFET region resistance than a low drift layer resistance to further improve the on-resistance. Device design, fabrication, and electrical characterization of the proposed 600 V, 10 A, 4H-SiC lateral single RESURF MOSFETs are discussed in this paper.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2013

TRIGGERED STAR FORMATION IN A BRIGHT-RIMMED CLOUD (BRC 5) OF IC 1805

We report recent optical, near-infrared (NIR), and millimeter observations which have revealed some new features of the bright-rimmed cloud BRC 5 associated with W4. With slitless spectroscopy, we detected 17 H{alpha} emission stars around the cloud; 4 are near the surface of the cloud, and 1 is toward IRAS 02252+6120. NIR photometry shows that the central H{alpha} emission star, together with one bright infrared source, has large NIR excesses and Class I spectral energy distributions. These two Class I objects are associated with the 2.9 mm continuum peaks and with a bipolar outflow, and are in between two separate, elongated C{sup 18}O(J = 1-0) cores. The C{sup 18}O cores and the two Class I sources are aligned along a line at position angle {approx}240 Degree-Sign , somewhat less than perpendicular to the direction of UV radiation from the OB stars. Most of the detected H{alpha} emission stars, all T Tauri candidates, are located within {approx}3' of the cloud on the exciting star side. An estimate of the age of the stars based on a color-magnitude diagram suggests that these T Tauri candidates have ages of {approx}1 Myr or less, but are more evolved objects than the central young stellar objects. This age sequence suggests sequential star formation within the BRC 5 cloud. The {sup 13}CO(J = 1-0) emission shows three elongated structures, which indicates the asymmetric structure toward the UV incident axis. We present our exploratory simulation results by using a smoothed particle hydrodynamic code that suggests that the asymmetrical BRC 5 structure could possibly result from the evolution of a preexisting prolate molecular cloud subject to radiation-driven implosion (RDI). Our best-fit prolate cloud has an initial mass of {approx}400 M{sub Sun }, an axial ratio of {approx}1.7, and a semi-major axis of {approx}1.6 pc, pointing away from the ionization flux by an angle of 15 Degree-Sign . The simulated cloud structure not only closely matches the observed asymmetric morphological structure of BRC 5, but also reveals the possibility of the development of two major cores at the head of BRC 5. For the first time, the possibility of forming two stars by an RDI mechanism in a BRC is investigated.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

3D IC for Future HEP Detectors

Three dimensional integrated circuit technologies offer the possibility of fabricating large area arrays of sensors integrated with complex electronics with minimal dead area, which makes them ideally suited for applications at the LHC upgraded detectors and other future detectors. Here we describe ongoing R&D efforts to demonstrate functionality of components of such detectors. This also includes the study of integrated 3D electronics with active edge sensors to produce "active tiles" which can be tested and assembled into arrays of arbitrary size with high yield.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2011

Effect of nearby Pearl vortices upon the Ic versus B characteristics of planar Josephson junctions in thin and narrow superconducting strips

In this paper I show how to calculate the effect of a nearby Pearl vortex or antivortex upon the critical current I{sub c}(B) when a perpendicular magnetic induction B is applied to a planar Josephson junction in a long, thin, superconducting strip of width W much less than the Pearl length {Lambda} = 2{lambda}2/d, where {lambda} is the London penetration depth and d is the thickness (d < {lambda}). The theoretical results provide a qualitative explanation of unusual features recently observed experimentally by Golod et al. [ Phys. Rev. Lett. 104 227003 (2010)] in a device with a similar geometry.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

An analysis of computational workloads for the ORNL Jaguar system. In: ICS '12 Proceedings of the 26th ACM international conference on Supercomputing

This study presents an analysis of science application workloads for the Jaguar Cray XT5 system during its tenure as a 2.3 petaflop supercomputer at Oak Ridge National Laboratory. Jaguar was the first petascale system to be deployed for open science and has been one of the world's top three supercomputers for six releases of the TOP500 list. Its workload is investigated here as a representative of the growing worldwide install base of petascale systems and also as a foreshadowing of science workloads to be expected for future systems. The study considers characteristics of the Jaguar workload such as resource utilization, typical job characteristics, most heavily used applications, application scaling and application usage patterns. Implications of these findings are considered for current petascale workflows and for exascale systems to be deployed later this decade.

Joubert, Wayne↗
DOE OSTI2013

HykSort: a new variant of hypercube quicksort on distributed memory architectures. In: ICS '13 Proceedings of the 27th international ACM conference on International conference on supercomputing

In this paper, we present HykSort, an optimized comparison sort for distributed memory architectures that attains more than 2× improvement over bitonic sort and samplesort. The algorithm is based on the hypercube quicksort, but instead of a binary recursion, we perform a k-way recursion in which the pivots are selected accurately with an iterative parallel select algorithm. The single-node sort is performed using a vectorized and multithreaded merge sort. The advantages of HykSort are lower communication costs, better load balancing, and avoidance of O(p)-collective communication primitives. We also present a staged communication samplesort, which is more robust than the original samplesort for large core counts. We conduct an experimental study in which we compare hypercube sort, bitonic sort, the original samplesort, the staged samplesort, and HykSort. We report weak and strong scaling results and study the effect of the grain size. It turns out that no single algorithm performs best and a hybridization strategy is necessary. As a highlight of our study, on our largest experiment on 262,144 AMD cores of the CRAY XK7 "Titan" platform at the Oak Ridge National Laboratory we sorted 8 trillion 32-bit integer keys in 37 seconds achieving 0.9TB/s effective throughput.

Sundar, Hari↗
DOE OSTI2012

Thermoelectric Conversion of Waste Heat to Electricity in an IC Engine Powered Vehicle

The thermoelectric generator shorting system provides the capability to monitor and short-out individual thermoelectric couples in the event of failure. This makes the series configured thermoelectric generator robust to individual thermoelectric couple failure. Open circuit detection of the thermoelectric couples and the associated short control is a key technique to ensure normal functionality of the TE generator under failure of individual TE couples. This report describes a five-year effort whose goal was the understanding the issues related to the development of a thermoelectric energy recovery device for a Class-8 truck. Likely materials and important issues related to the utility of this generator were identified. Several prototype generators were constructed and demonstrated. The generators developed demonstrated several new concepts including advanced insulation, couple bypass technology and the first implementation of skutterudite thermoelectric material in a generator design. Additional work will be required to bring this system to fruition. However, such generators offer the possibility of converting energy that is otherwise wasted to useful electric power. Uur studies indicate that this can be accomplished in a cost-effective manner for this application.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2013

Yearly Report for the Period Jan-Dec 2012: IC PROJECT W12c_earthuq - “High-Performance Computing for Uncertainty Quantification of 3D Earth Models”

This proposal was written to be a new project leveraging on computational achievements of the two IC11 proposals “3D Geophysical Modeling Validation” and “Time-Reversal Imaging of tremor sources”. W12c_earthuq involves additional codes/tools other than SPECFEM3D for data processing and planned a strong effort to move toward modeling at much larger scales than the aforementioned projects. W12c_earthuq goal was to use extensive HPC resources at LANL to assess the uncertainty of high resolution 3D geophysical models. Validation of these models as planned in W11_geophys is the first step in a full assessment of uncertainty. So, the scientific and programmatic impacts of this project are the same as W11_geophys. The main effort related to w12c_earthuq is the preparation to transition to large runs with a resolution down to 2s. We already report the work done in the report for w11_geophys. Such resolution requires meshes with 10 billions elements with a size of about 5km and a few thousands of compute nodes. First tests on mustang have revealed that the I/O part of the code need to be reviewed because it opens too many files in its current version.

58 GEOSCIENCES↗
DOE OSTI2014

IC W13_auptphase Highlight: Phase Diagram of Pt from Z Methodology

Pt phase diagram from combining the Z methodology with the fcc-rhcp (face-centered cubic -- random hexagonal closepacked) solid-solid phase boundary. The experimental melting curve of Pt is shown as dashed blue line. Solid-solid phase boundaries in Figs. 1 and 2 are consistent with each other. Phase diagram of Pt from the Z methodology: fcc-Pf melting curve (green line), liquid Pt solidified into solid fcc (green bullets), 9R-Pt melting curve (blue line), liquid Pt solidified into solid 9R (blue bullets), and the (tentative) fcc-9R solid-solid phase boundary (violet).

36 MATERIALS SCIENCE↗