From generic towards a micromechanical fatigue model

AbstractFatigue life formulas are still based on phenomenological models which adopt simple relations directly from experiments for different loading conditions and use fitted material parameters. The combination of enormous complexity of fatigue damage processes and simple, macro appearance of the formulas (usually power laws), are the source of Generic Fatigue Models (GFM). GFMs rely on minimal, but coherent, micro-details which are independent of the specific micro structure. Such a model has been developed, connecting analytically the S-N power law and endurance stress in terms of statistical strength distributions of material microelements and their neighbors.This paper describes two types of generalizations of the basic GFM: a.) Two level (H-L and L-H) loading, in which a history dependent micro-damage evolution law is proposed, and b.) Multiaxial fatigue response by a simple 2D truss. Emphasize is on minimal parameters and capability of analytical predictions, in which every “material constant” has a physical or micro-geometrical meaning. The theoretical generalizations are compared with experimental data from the literature and show that the predictions are coherent with main experimental features

Modeling plasticity by non-continuous deformation

Plasticity and failure theories are still subjects of intense research. Yet, no compre-hensive theory has been achieved and the Molecular Dynamic method is far from providing a general model which contains only the essentials. This study is motivated by the observation that the continuum assumption in plasticity that neighbour material elements remain neigh-bours at all-time are physically impossible, since neighbour detachments, local slips and neighbour switching must operate, i.e., Non-Continuous Deformation (NCD). Material micro-structure is modelled by a set of point elements (particles) interacting with their neighbours. Each particle can detach from its neighbours and/or attach to a new neighbour during defor-mation. Simulations on two dimensional specimens subjected to uniaxial compression loading and unloading were conducted. Each specimen contained 100 particles with stochastic hetero-geneity controlled by a “disorder” parameter λ. It was found that a. the macro response is typ-ical to elasto-plastic behaviour; b. The number of detachments is linear with plastic energy; c. The number of attachments is linear with the residual strain, and d. Volume is preserved under plastic deformation. Rigid body displacement of local ensemble of elements was also ob-served. Higher disorder coefficient λ decreases the macro elastic modulus and increases the plastic energy

Journal Article – The Work of Psychologists in the Ninth Service Command Special Training Center

An article published in the March 1944 issue of the Psychological Bulletin, titled The Work of Psychologists in the Ninth Service Command Special Training Center that describes the Special Training Unit Program at military bases in the western United States.https://scholarworks.moreheadstate.edu/stu_1210th_fort_ontario/1059/thumbnail.jp

Contaminant mobilisation by fluid-rock interaction and related transport mechanisms in platinum tailings

Contaminant release and transport in platinum tailings are poorly studied in literature. This study serves to characterise these processes. The tailings facility is located in Steelpoort, Mpumalanga, South Africa on Critical Zone rocks of the Rustenburg Layered Suite in The Bushveld Igneous Complex. Tailings material samples were collected by hand auger- and direct push probe drilling at specific locations to represent the different materials present in the tailings facility. Water samples were collected from monitoring boreholes as well as the Steelpoort River. The samples were analysed using XRD, XRF, ABA, NAG, Reflected Light Microscopy, Acid Leaching Tests and ICP scans. Using the collected data, a geochemical model was constructed for the interpretation of mineral phase dissolution and to trace the mineral phases releasing contaminants. Analysis-, test- and modelling results showed that alteration mineral phases formed within ten years in the tailings material and that the existing alteration phases viz. talc and chlorite, as well as sulphides, are the major contributors of contaminants. Elevated pH values as well as major cation and anion concentrations were found in the fluid discharging from the tailings as well as the in groundwater, with little to no heavy metals, which were traced directly to the chromite phase. This suggests that platinum tailings do not contribute to heavy metal contamination or acid rock drainage but may increase aquifer salinity and alkalinity. The flow through the tailings, underlying vadose zone and fractured rock aquifer was characterised using permeameter- and pumping tests. From the data collected, an unsaturated flow model was developed to characterise the flow through the tailings. From the model, discharge from the tailings was calculated to take place at 0.7m per decade into the underlying vadose zone with fracture flow in the aquifer ranging from 0.46-0.026m/d, as calculated from pumping test results. Contaminant migration into the Steelpoort River is possibly inhibited by the Dwarsriver Fault, based on the chemical data and hydraulic conductivities calculated. Therefore, groundwater is considered to be the major receptor in the system and groundwater users may be negatively impacted by increasing groundwater salinity and major ion concentrations.Dissertation (MSc)--University of Pretoria, 2013.Geologyunrestricte

A style discussion of Strange Quartet, Wits Trio Tribute, and Quin-tête-à-tête : three chamber works of Jeanne Zaidel-Rudolph composed between 2000-2019

The chamber works of Jeanne Zaidel-Rudolph encapsulate a world of stylised nuances. Yet, little has been written about these works, especially those composed after the year 2000. They portray a period in the composer’s compositional career during which she implemented an instinctive approach to composing. However, the composer’s compositional fingerprints permeate these works. This present study aims to analyse and present this style-producing syntax to better understand the composer’s chamber works and the compositional period during which these works were composed (post-2000). These style aspects are grouped and discussed according to the following topics: structure, melodic content, harmonic content, rhythm, and texture. These discussions provide valuable insights into Zaidel-Rudolph’s style, which include melodic writing based on pitch-class sets extracted from non-diatonic scales; interval preference; recurring harmonic structures comprising verticalized tri-, tetra-, and pentachords; quartal and quintal structures; split-member harmonies and added note chords; rhythmic structures expanded and modified to serve as motivic cohesion; and the utilisation of a rich diversity of textures to function as structure-contributing elements. Range and density factors also contribute to structure formation. This study incorporates multiple illustrative music examples and graphics to elucidate the discussed topics and aims to supply analytical information to performers, composers and analysts.Thesis (DMus (Composition))--University of Pretoria, 2021.UP DOCTORAL RESEARCH BURSARYMusicDMus (Composition)Unrestricte

Defining Archetypes and Requirements for mHealth Interventions in Rural Kenya: An Investigation in Collaboration with CURAFA™

Designing and implementing successful mobile health (mHealth) applications is always challenging, but even more so in countries and communities in rural areas where the target population have access to limited resources. While some mHealth initiatives have shown success and potential in Kenya, still too many fail. One of the reasons for failure is the limited understanding of the health-seeking behavior and social-technological context of the rural Kenyan population. This study aims to use a mixed-method approach to define archetypes of rural Kenyan patients and translate them into requirements which can guide the design and implementation of user-centric mHealth interventions in rural Kenya. With this study, we show how practitioners can leverage existing organizational and social structures in developing countries to develop mobile health applications tailored to patients’ needs

Supporting Subject Matter Experts as Developers: Towards a Framework for Decentralized Robotic Process Automation Development

Robotic Process Automation (RPA) has emerged as promising automation technology in recent years. Firms seize RPA for fast and cost-efficient low-code process automation implemented and maintained decentrally in the business units by subject matter experts (SMEs) without IT development experience. However, decentralized RPA projects are reported to frequently fail and be prone to challenges as SMEs struggle to meet their new roles and responsibilities, such as developers or testers. Yet, research lacks an understanding of how challenges related to SMEs' roles and responsibilities unfold and how to address these challenges when executing decentralized RPA projects. To this end, our study employs a Design Science Research approach, drawing on literature and 14 expert interviews, to (1) systematically synthesize the challenges related to SMEs' roles and responsibilities and (2) derive a software development framework for supporting SMEs in their new roles and responsibilities in decentralized RPA projects. Thus, our study contributes to RPA and low-code development research and provides SMEs with guidelines to navigate decentralized RPA projects in practice

B. F. Skinner's contributions to applied behavior analysis

Our paper reviews and analyzes B. F. Skinner's contributions to applied behavior analysis in order to assess his role as the field's originator and founder. We found, first, that his contributions fall into five categorizes: the style and content of his science, his interpretations of typical and atypical human behavior, the implications he drew from his science for application, his descriptions of possible applications, and his own applications to nonhuman and human behavior. Second, we found that he explicitly or implicitly addressed all seven dimensions of applied behavior analysis. These contributions and the dimensions notwithstanding, he neither incorporated the field's scientific (e.g., analytic) and social dimensions (e.g., applied) into any program of published research such that he was its originator, nor did he systematically integrate, advance, and promote the dimensions so to have been its founder. As the founder of behavior analysis, however, he was the father of applied behavior analysis