Improving Interoperability by Incorporating UnitsML Into Markup Languages

Maintaining the integrity of analytical data over time is a challenge. Years ago, data were recorded on paper that was pasted directly into a laboratory notebook. The digital age has made maintaining the integrity of data harder. Nowadays, digitized analytical data are often separated from information about how the sample was collected and prepared for analysis and how the data were acquired. The data are stored on digital media, while the related information about the data may be written in a paper notebook or stored separately in other digital files. Sometimes the connection between this “scientific meta-data” and the analytical data is lost, rendering the spectrum or chromatogram useless. We have been working with ASTM Subcommittee E13.15 on Analytical Data to create the Analytical Information Markup Language or AnIML—a new way to interchange and store spectroscopy and chromatography data based on XML (Extensible Markup Language). XML is a language for describing what data are by enclosing them in computer-useable tags. Recording the units associated with the analytical data and metadata is an essential issue for any data representation scheme that must be addressed by all domain-specific markup languages. As scientific markup languages proliferate, it is very desirable to have a single scheme for handling units to facilitate moving information between different data domains.At NIST, we have been developing a general markup language just for units that we call UnitsML. This presentation will describe how UnitsML is used and how it is being incorporated into AnIML.     

Repair of composite structures on Formula 1 race cars

The chassis of a Formula 1 car is constructed for the most part from carbon fibre reinforced composite materials. Primary structures such as the monocoque/survival cell, suspension and gearboxes and the overwhelming majority of secondary (wings, bodywork, etc.) structures are routinely produced using such materials. During the operation of the vehicles it is fairly commonplace for composite components to sustain a degree of damage. The level of damage varies from being very minor (small holes and dents from stone strikes, etc.) to very serious structural damage to major components resulting from accidents. Although F1 Teams operate with large budgets, the funding available is finite and the logistics very tight such that there is a need, wherever possible, to repair and return to service damaged parts rather than scrap and replace them. This must of course be done in such a way that the safety and performance of the cars are in no way compromised. The repair of composite structures is far from a trivial exercise; the degree of damage must be assessed and a repair scheme “designed” and implemented in the shortest possible time. The degree of invasive “surgery” is kept to the minimum and all corrective work carried out must be fully documented and capable of future condition monitoring as part of the team’s total quality management (TQM) process. Additionally, repair techniques may be used to reverse progressive damage (analogous to metal fatigue) within composite structures thus preventing major failures and extending their service lives. Commonly used repair techniques and methodologies are discussed and illustrated with practical examples culminating with the repair of major structural damage to the monocoque.     

Dissolution and Interface Reactions between Palladium and Tin(Sn)-Based Solders: Part II. 63Sn-37Pb Alloy

The interface microstructures and dissolution behavior were studied, which occur between 99.9 pct Pd substrates and molten 95.5Sn-3.9Ag-0.6Cu (wt pct, Sn-Ag-Cu) solder. The solder bath temperatures were 513 K to 623 K (240 °C to 350 °C). The immersion times were 5 to 240 seconds. The IMC layer composition exhibited the (Pd, Cu)Sn₄ (Cu, 0 to 2 at. pct) and (Pd, Sn) solid-solution phases for all test conditions. The phases PdSn and PdSn₂ were observed only for the 623 K (350 °C), 60 seconds test conditions. The metastable phase, Pd₁₁Sn₉, occurred consistently for the 623 K (350 °C), 240 seconds conditions. Palladium-tin needles appeared in the Sn-Ag-Cu solder, but only at temperatures of 563 K (290 °C ) or higher, and had a (Pd, Cu)Sn₄ stoichiometry. Palladium dissolution increased monotonically with both solder bath temperature and exposure time. The rate kinetics of dissolution were represented by the expression At ⁿ exp(∆H/RT), where the time exponent (n) was 0.52 ± 0.10 and the apparent activation energy (∆H) was 44 ± 9 kJ/mol. The IMC layer thickness increased between 513 K and 563 K (240 °C and 290 °C) to approximately 3 to 5 μm, but then was less than 3 μm at 593 K and 623 K (320 °C and 350 °C). The thickness values exhibited no significant time dependence. As a protective finish in electronics assembly applications, Pd would be relatively slow to dissolve into molten Sn-Ag-Cu solder. The Pd-Sn IMC layer would remain sufficiently thin and adherent to a residual Pd layer so as to pose a minimal reliability concern for Sn-Ag-Cu solder interconnections.     

A scenario analysis of investment options for the Cuban power sector using the MARKAL model

The Cuban power sector faces a need for extensive investment in new generating capacity, under a large number of uncertainties regarding future conditions, including: rate of demand growth, fluctuations in fuel prices, access to imported fuel, and access to investment capital for construction of new power plants and development of fuel import infrastructure. To identify cost effective investment strategies under these uncertainties, a supply and power sector MARKAL model was assembled, following an extensive review of available data on the Cuban power system and resource potentials. Two scenarios were assessed, a business-as-usual (BAU) scenario assuming continued moderate electricity load growth and domestic fuel production growth, and a high growth (HI) scenario assuming rapid electricity demand growth, rapid increase in domestic fuel production, and a transition to market pricing of electricity. Within these two scenarios sets, sensitivity analyses were conducted on a number of variables. The implications of least-cost investment strategies for new capacity builds, investment spending requirements, electricity prices, fuel expenditures, and carbon dioxide emissions for each scenario were assessed. Natural gas was found to be the cost effective fuel for new generation across both scenarios and most sensitivity cases, suggesting that access to natural gas, through increased domestic production and LNG import, is a clear priority for further analysis in the Cuban context.     

Surface interfaces in low temperature water-gas shift: The metal oxide synergy,the assistance of co-adsorbed water,and alkali doping

With new developments in polymer electrolyte membrane fuel cells, interest is growing in fuel processor technology for converting feedstocks to hydrogen. One critical step in the process to convert CO and purify hydrogen is low temperature water-gas shift (LTS). Control of the LTS rate can be achieved by designing catalysts in a way that produces and rapidly decomposes the surface formate anion intermediate. In this account, examples are provided to demonstrate various interfacial phenomena important for achieving these goals. The interface between a metal and a partially reducible oxide promotes surface reduction of the oxide to the low temperature range, generating sites for the low temperature activation of H₂O on the oxide. Partial reduction of the oxide and surface activation of H₂O at low temperature provide a route for formate production at low temperature. Adjacent co-adsorbed water molecules participate in the transition state of formate decomposition, accelerating the formate turnover rate and altering the selectivity to favor dehydrogenation. The rate-limiting-step involves formate C–H bond scission, with the metal abstracting hydrogen at the interface between metal and oxide, serving as a conduit for hydrogen release. Catalysts may be improved by increasing formate mobility on the oxide; furthermore, the optimization of alkali doping levels can electronically promote formate C–H bond scission.     

Characteristics of the Transformation of Retained Austenite in Tempered Austempered Ductile Iron

Controlling the amount of retained austenite is a concern in austempered ductile iron formation. Retained austenite has a strong influence on austempered ductile iron properties, such as hardness and wear resistance. In this research, the characteristics of the transformation of retained austenite were investigated as a function of the number of tempering cycles. The hardness of the austempered ductile iron samples was measured, and the specific amount of retained austenite was analyzed by x-ray diffraction (XRD). Wear tests were conducted on a ball-on-flat sliding fixture. The tempering process was found to have no effect on the hardness of the austempered ductile iron samples. This may be due to retained austenite being partially converted into brittle quenched martensite during the tempering process. However, tougher tempered martensite was also formed from existing martensite. The two effects seemed to offset each other, and no significant differences occurred in overall hardness. XRD analysis showed that under the same austempering temperature and holding time, the amount of retained austenite decreased with additional tempering cycles. Also, with the same holding time and tempering cycles, less retained austenite was contained in the matrix at higher austempering temperatures. This was due to more high carbon content austenite and needle-like ferrite being present in the austempered ductile iron matrix. In addition, tempered austempered ductile iron exhibited significantly higher wear resistance as compared to traditionally treated ductile iron.     

Oxidation of Alloy 600 and Alloy 690: Experimentally Accelerated Study in Hydrogenated Supercritical Water

The objective of this study is to determine whether the oxidation of Alloys 600 and 690 in supercritical water occurs by the same mechanism in subcritical water. Coupons of Alloys 690 and 600 were exposed to hydrogenated subcritical and supercritical water from 633 K to 673 K (360 °C to 400 °C) and the oxidation behavior was observed. By all measures of oxide character and behavior, the oxidation process is the same above and below the supercritical line. Similar oxide morphologies, structures, and chemistries were observed for each alloy across the critical point, indicating that the oxidation mechanism is the same in both subcritical and supercritical water. Oxidation results in a multi-layer oxide structure composed of particles of NiO and NiFe₂O₄ formed by precipitation on the outer surface and a chromium-rich inner oxide layer formed by diffusion of oxygen to the metal-oxide interface. The inner oxide on Alloy 600 is less chromium rich than that observed on Alloy 690 and is accompanied by preferential oxidation of grain boundaries. The inner oxide on Alloy 690 initially forms by internal oxidation before a protective layer of chromium-rich MO is formed with Cr₂O₃ at the metal-oxide interface. Grain boundaries in Alloy 690 act as fast diffusion paths for chromium that forms a protective Cr₂O₃ layer at the surface, preventing grain boundary oxidation from occurring.     

Accelerated Stress Corrosion Crack Initiation of Alloys 600 and 690 in Hydrogenated Supercritical Water

The objective of this study is to determine whether stress corrosion crack initiation of Alloys 600 and 690 occurs by the same mechanism in subcritical and supercritical water. Tensile bars of Alloys 690 and 600 were strained in constant extension rate tensile experiments in hydrogenated subcritical and supercritical water from 593 K to 723 K (320 °C to 450 °C), and the crack initiation behavior was characterized by high-resolution electron microscopy. Intergranular cracking was observed across the entire temperature range, and the morphology, structure, composition, and temperature dependence of initiated cracks in Alloy 690 were consistent between hydrogenated subcritical and supercritical water. Crack initiation of Alloy 600 followed an Arrhenius relationship and did not exhibit a discontinuity or change in slope after crossing the critical temperature. The measured activation energy was 121 ± 13 kJ/mol. Stress corrosion crack initiation in Alloy 690 was fit with a single activation energy of 92 ± 12 kJ/mol across the entire temperature range. Cracks were observed to propagate along grain boundaries adjacent to chromium-depleted metal, with Cr₂O₃ observed ahead of crack tips. All measures of the SCC behavior indicate that the mechanism for stress corrosion crack initiation of Alloy 600 and Alloy 690 is consistent between hydrogenated subcritical and supercritical water.