Integral equations of a cohesive zone model for history-dependent materials and their numerical solution

A nonlinear history-dependent cohesive zone (CZ) model of quasi-static crack propagation in linear elastic and viscoelastic materials is presented. The viscoelasticity is described by a linear Volterra integral operator in time. The normal stress on the CZ satisfies the history-dependent yield condition, given by a nonlinear Abel-type integral operator. The crack starts propagating, breaking the CZ, when the crack tip opening reaches a prescribed critical value. A numerical algorithm for computing the evolution of the crack and CZ in time is discussed along with some numerical results

Principles of Nutrition (GHC)

This Grants Collection for Principles of Nutrition was created under a Round Nine ALG Textbook Transformation Grant. Affordable Learning Georgia Grants Collections are intended to provide faculty with the frameworks to quickly implement or revise the same materials as a Textbook Transformation Grants team, along with the aims and lessons learned from project teams during the implementation process. Documents are in .pdf format, with a separate .docx (Word) version available for download. Each collection contains the following materials: Linked Syllabus Initial Proposal Final Reporthttps://oer.galileo.usg.edu/health-collections/1007/thumbnail.jp

Principles of Nutrition Textbook, Second Edition

Update: The team has updated this course with a Round Twelve Mini-Grant for Ancillary Materials and Revisions, leading to a new twenty-chapter remix featuring content from a Kansas State University open textbook. Due to accessibility issues in the repository, a second copy of the PDF without a cover page is included in Additional Files. This file should retain all bookmarks and tags. First edition description: This Open Textbook for Principles of Nutrition was created under a Round Nine ALG Textbook Transformation Grant. Topics covered: Chapter 1: Nutrition Basics Chapter 2: Macronutrient Structures Chapter 3: Macronutrient Digestion Chapter 4: Macronutrient Uptake, Absorption, & Transport Chapter 5: Common Digestive Problems Chapter 6: Macronutrient Metabolism Chapter 7: Integration of Macronutrient Metabolism Chapter 8: Micronutrients Overview & Dietary Reference Intakes (DRIs) Chapter 9: Antioxidant Micronutrients Chapter 10: Macronutrient Metabolism Micronutrients Chapter 11: Carbon Metabolism Micronutrients Chapter 12: Blood, Bones & Teeth Micronutrients Chapter 13: Electrolyte Micronutrients Chapter 14: Achieving a Healthy Diet Chapter 15: Diet and Health- Chronic Disease Prevention Chapter 16: Pregnancy and Lactation Chapter 17: Nutrition Infancy through Adolescence Chapter 18: Adulthood and the Later Years Chapter 19: Nutrition and Fitness/Athletes Chapter 20: Nutrition and Society The original chapters are also available on a Georgia Highlands College LibGuide.https://oer.galileo.usg.edu/health-textbooks/1006/thumbnail.jp

Principles of Biology I & II (GHC)

This Grants Collection for Principles of Biology I & II was created under a Round Eleven ALG Textbook Transformation Grant. Affordable Learning Georgia Grants Collections are intended to provide faculty with the frameworks to quickly implement or revise the same materials as a Textbook Transformation Grants team, along with the aims and lessons learned from project teams during the implementation process. Documents are in .pdf format, with a separate .docx (Word) version available for download. Each collection contains the following materials: Linked Syllabus Initial Proposal Final Reporthttps://oer.galileo.usg.edu/biology-collections/1024/thumbnail.jp

The Plasma and Suprathermal Ion Composition (PLASTIC) investigation on the STEREO observatories

The Plasma and Suprathermal Ion Composition (PLASTIC) investigation provides the in situ solar wind and low energy heliospheric ion measurements for the NASA Solar Terrestrial Relations Observatory Mission, which consists of two spacecraft (STEREO-A, STEREO-B). PLASTIC-A and PLASTIC-B are identical. Each PLASTIC is a time-of-flight/energy mass spectrometer designed to determine the elemental composition, ionic charge states, and bulk flow parameters of major solar wind ions in the mass range from hydrogen to iron. PLASTIC has nearly complete angular coverage in the ecliptic plane and an energy range from ∼0.3 to 80 keV/e, from which the distribution functions of suprathermal ions, including those ions created in pick-up and local shock acceleration processes, are also provided

Tracing injected CO2 in the Cranfield enhanced oil recovery field (MS, USA) using He, Ne and Ar isotopes

The He, Ne and Ar isotopic composition of gases collected in 2009 and 2012 from 13 production wells, injection wells and the CO2 supply pipeline at the Cranfield CO2-enhanced oil recovery field (MS, USA) have been measured in order to determine the extent to which they trace the fate of injected CO2 in the reservoir. In the absence of samples of CO2 pre-injection reservoir gas we use the Ne isotope composition of the production and injection well gases to determine the isotopic composition of the natural gas. The noble gas isotopes display binary mixing trends between the injected CO2 and a CH4-rich natural gas that is characterised by radiogenic He, Ne and Ar isotope ratios. 3He/4He and 40Ar*/4He ratios (where 40Ar* represents the non-atmospheric 40Ar) display coherent relationships with CO2 concentrations that can be used to trace and quantify the injected CO2 in an engineered site over a sustained period of injection. The presence of a small amount of air-derived Ar, from a non-atmospheric source, in many gas samples rules out using 40Ar/36Ar to track the injected CO2. The noble gases identify the loss of a significant proportion of the CO2 from the gas phase sampled by five production wells in 2009. Using 3He/4He and 40Ar*/4He ratios to reconstruct the major gas composition, it appears that between 22% and 96% of the CO2 has been lost in individual wells. This study demonstrates that the naturally occurring noble gases have the potential to trace the fate and quantify the sequestration of CO2 at injection sites

Principles of Biology II Lab Manual (Georgia Highlands College)

This laboratory manual for Principles of Biology II with ancillary materials was created and revised under a Round Thirteen Mini-Grant. Topics include evolution, bacteria, protists, plants, fungi, sponges and jellyfish, flatworms and nematodes, mollusks and annelids, arthropods and echinoderms, chordates and mammals, and mammalian anatomy. The lab manual is separated by chapters, as are the PowerPoint slides and lab quizzes

Multifunctional porous catalyst produced by mechanical alloying

Mechanical alloying has been repeatedly demonstrated as an effective means to create unique structural materials, but it is comparatively rare that functional alloys are produced. Multi-phase functional alloy production is demonstrated with an oxide-dispersed Ni–Cu catalyst. These catalyst particles are designed to form porosity and catalyze carbon nanofiber deposition in situ, which results in a six-fold increase in deposition rate over traditional preparation methods. This technique serves as a template for many other systems possible with MA

Enhanced Performance of Bimetallic Co-Pd Catalysts Prepared by Mechanical Alloying

Bimetallic catalysts can provide enhanced performance, and Co-based catalysts in particular have been studied in various respects for their activity in the deposition of carbon nanofibers (CNFs). The majority of studies on CNF catalysis use co-precipitation to create alloys, but recent work has demonstrated the suitability of mechanical alloying (MA) by ball milling to reduce cost and increase catalytic activity. This work establishes the unique ability of MA to control the microstructure to produce bimetallic composites, which retain distinct metallic phases that improve catalytic activity. It is demonstrated that Co-Pd alloys reach a maximum in catalytic activity at an intermediate time of mechanical activation, where 30 min of milling outperformed samples milled for 5, 15, 60, and 240 min at a reaction temperature of 550 °C and a 1:4 C2H4:H2 reactant ratio. This indicates there is benefit to retaining the metals in distinct phases in close proximity. Ball milling provides a relatively simple and scalable method to achieve these unique microstructures, and in the optimal condition tested here, the activity toward carbon deposition is increased fourfold over prior work. Furthermore, the minimum temperature for deposition is also reduced. The characteristics of these materials, the effects of milling and annealing, and the underlying mechanisms of deposition are discussed