Advancing Alternative Analysis: Integration of Decision Science.

Decision analysis-a systematic approach to solving complex problems-offers tools and frameworks to support decision making that are increasingly being applied to environmental challenges. Alternatives analysis is a method used in regulation and product design to identify, compare, and evaluate the safety and viability of potential substitutes for hazardous chemicals.Assess whether decision science may assist the alternatives analysis decision maker in comparing alternatives across a range of metrics.A workshop was convened that included representatives from government, academia, business, and civil society and included experts in toxicology, decision science, alternatives assessment, engineering, and law and policy. Participants were divided into two groups and prompted with targeted questions. Throughout the workshop, the groups periodically came together in plenary sessions to reflect on other groups' findings.We conclude the further incorporation of decision science into alternatives analysis would advance the ability of companies and regulators to select alternatives to harmful ingredients, and would also advance the science of decision analysis.We advance four recommendations: (1) engaging the systematic development and evaluation of decision approaches and tools; (2) using case studies to advance the integration of decision analysis into alternatives analysis; (3) supporting transdisciplinary research; and (4) supporting education and outreach efforts

Commissioning of the vacuum system of the KATRIN Main Spectrometer

The KATRIN experiment will probe the neutrino mass by measuring the beta-electron energy spectrum near the endpoint of tritium beta-decay. An integral energy analysis will be performed by an electro-static spectrometer (Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m^3, and a complex inner electrode system with about 120000 individual parts. The strong magnetic field that guides the beta-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300{\deg}C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure

DOE-DARPA High-Performance Corrosion-Resistant Materials (HPCRM), Annual HPCRM Team Meeting & Technical Review

The overall goal is to develop high-performance corrosion-resistant iron-based amorphous-metal coatings for prolonged trouble-free use in very aggressive environments: seawater & hot geothermal brines. The specific technical objectives are: (1) Synthesize Fe-based amorphous-metal coating with corrosion resistance comparable/superior to Ni-based Alloy C-22; (2) Establish processing parameter windows for applying and controlling coating attributes (porosity, density, bonding); (3) Assess possible cost savings through substitution of Fe-based material for more expensive Ni-based Alloy C-22; (4) Demonstrate practical fabrication processes; (5) Produce quality materials and data with complete traceability for nuclear applications; and (6) Develop, validate and calibrate computational models to enable life prediction and process design

Commissioning of the vacuum system of the KATRIN Main Spectrometer

The KATRIN experiment will probe the neutrino mass by measuring the -electron energy spectrum near the endpoint of tritium -decay. An integral energy analysis will be performed by an electro-static spectrometer (“Main Spectrometer”), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240m3, and a complex inner electrode system with about 120 000 individual parts. The strong magnetic field that guides the -electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300 C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10$^{-11}$ mbar range. It is demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016

Implications of Pb-free microelectronics assembly in aerospace applications

The commercial microelectronics industry is rapidly implementing Pb-free assembly strategies and it should be mostly Pb free within the next decade. This trend is driven by existing and proposed legislation in Europe and in Japan, which has already led a number of firms (including AT&T, IBM, Motorola, Hewlett-Packard, and Intel) to adopt Pb-free implementation programs. This is another sign that the microelectronics industry has become truly global. Following Moore's law, progress in microelectronics is brisk but not uniform: in many cases, commercial industry is ahead of the aerospace sector in technology. Progress by commercial industry, along with cost, drives the use of commercial off-the-shelf parts for military and space applications. We can thus anticipate that the U.S. aerospace industry, which is not subject to foreign legislation, will, at some point, be forced to use Pb-free components and subsystems as part of their standard business practices. In this, paper, we provide a snapshot of the commercial industry trends and how they may impact electronics in the aerospace environment. Impacts will be felt in the areas of reliability, assembly methods, cost drivers, supply chain selection, and alternative materials selection. In addition, we look at different strategies for implementation. The questions we address include the following: Should companies immediately embark on a program to convert all of their electronics to Ph free? Should they phase it in instead, and if so, over what time frame? Should companies try to comply with industry Pb-free standards? What requirements should flow down to subcontractors and component suppliers? Legislation is pending in a number of states that may affect these decisions and their timing. The U.S. Environmental Protection Agency, through some university programs, is examining the implementation of Ph free as well. Finally, we present data from a portion of a recent NASA project that focuses on finding suitable alternatives to eutectic Sn-Pb solders and solder pastes and on determining suitable processing operations in assembling printed wiring boards. The world is moving toward implementation of environmentally friendly manufacturing techniques. The aerospace industry will be forced to deal with issues related to Pb-free assembly, either because of the progressive scarcity of eutectic Sn-Pb solder or because of legislation. This paper provides insights into some of the key tradeoffs that should be considered

Process-Structure-Property Relationships for 316L Stainless Steel Fabricated by Additive Manufacturing and Its Implication for Component Engineering

© 2016, ASM International. We investigate the process-structure-property relationships for 316L stainless steel prototyping utilizing 3-D laser engineered net shaping (LENS), a commercial direct energy deposition additive manufacturing process. The study concluded that the resultant physical metallurgy of 3-D LENS 316L prototypes is dictated by the interactive metallurgical reactions, during instantaneous powder feeding/melting, molten metal flow and liquid metal solidification. The study also showed 3-D LENS manufacturing is capable of building high strength and ductile 316L prototypes due to its fine cellular spacing from fast solidification cooling, and the well-fused epitaxial interfaces at metal flow trails and interpass boundaries. However, without further LENS process control and optimization, the deposits are vulnerable to localized hardness variation attributed to heterogeneous microstructure, i.e., the interpass heat-affected zone (HAZ) from repetitive thermal heating during successive layer depositions. Most significantly, the current deposits exhibit anisotropic tensile behavior, i.e., lower strain and/or premature interpass delamination parallel to build direction (axial). This anisotropic behavior is attributed to the presence of interpass HAZ, which coexists with flying feedstock inclusions and porosity from incomplete molten metal fusion. The current observations and findings contribute to the scientific basis for future process control and optimization necessary for material property control and defect mitigation

Rate-dependent behavior of hierarchical Al matrix composites

We present the rate-dependent constitutive response of hierarchical Al matrix composites which comprise a bi-modal distribution of Al in fine (nanocrystalline Al containing micro-sized B 4 C particles) and coarse (micro-grained Al) grain regimes. The strength of these composites is improved by various strengthening mechanisms. Shear localization is observed to be the primary failure mode. Compared to quaistatic loading, significant increase of strain to failure is observed at high strain rates. Varying rate-sensitivity is observed with different amount of B 4 C particles. Ó 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Hierarchical microstructure; Length-scale effects; Rate-dependent behavior; Metal matrix composite; Strain-to-failure Particulate-reinforced metal matrix composites (PMMCs) have been identified as attractive materials for numerous applications due to their excellent mechanical and physical properties, ease of manufacture, and low cost of production. One particular application is to work as armors or protective coatings in military or aerospace structures where the materials are often subject to explosive blast loading and dynamic impact. In these applications, understanding the rate-dependent high-strain-rate behavior of PMMCs is important. A conventional PMMC usually contains two-phases: hard ceramic particles as the reinforcement and a ductile metal as the matrix. The reinforcement particles provide high stiffness and strength to the composite and the metal matrix provides a compliant support for the reinforcement. The strength of PMMCs can be improved by increasing the volume fraction of the reinforcement particles. However, damage such as particle cracking or debonding of particle/matrix interface [1] is usually associated with deformation, and impairs the mechanical properties of PMMCs. As a result, a practical limit of the reinforcement volume fraction exists in fabricating PMMCs. Another approach to improve the strength of PMMCs is to increase the strength of the matrix. Various methods have been used and possibly the most common one is to decrease the grain size In this paper, we investigated the compressive constitutive response and failure of three tri-modal composites (composed of micron-grain-sized (MG) Al, nanocrystalline (NC) Al, and micron-sized B 4 C particles) at both quasistatic and dynamic strain rates. In dynamic loading, high-speed photography is used to reveal the dynamic failure of these tri-modal composites. This work is an extension to high strain rates of our findings on the super-high strength of similar tri-modal composites under quasistatic loading These tri-modal composites were produced from a two-step powder mixing (cryomilling and subsequent blending) and hot extrusion proces