Thermophysical Phenomena in Metal Additive Manufacturing by Selective Laser Melting: Fundamentals, Modeling, Simulation and Experimentation

Among the many additive manufacturing (AM) processes for metallic materials, selective laser melting (SLM) is arguably the most versatile in terms of its potential to realize complex geometries along with tailored microstructure. However, the complexity of the SLM process, and the need for predictive relation of powder and process parameters to the part properties, demands further development of computational and experimental methods. This review addresses the fundamental physical phenomena of SLM, with a special emphasis on the associated thermal behavior. Simulation and experimental methods are discussed according to three primary categories. First, macroscopic approaches aim to answer questions at the component level and consider for example the determination of residual stresses or dimensional distortion effects prevalent in SLM. Second, mesoscopic approaches focus on the detection of defects such as excessive surface roughness, residual porosity or inclusions that occur at the mesoscopic length scale of individual powder particles. Third, microscopic approaches investigate the metallurgical microstructure evolution resulting from the high temperature gradients and extreme heating and cooling rates induced by the SLM process. Consideration of physical phenomena on all of these three length scales is mandatory to establish the understanding needed to realize high part quality in many applications, and to fully exploit the potential of SLM and related metal AM processes

Certificate written to Henderick Smock for 10 pounds, signed by William W. Houghton and John Hart

Certificate written to Henderick Smock for £10 for sitting in assembly at Princeton in April 1778.https://digitalcommons.wofford.edu/littlejohnmss/1069/thumbnail.jp

Mitigating Cotton Revenue Risk Through Irrigation, Insurance, and Hedging

This study focuses on managing cotton production and marketing risks using combinations of irrigation levels, put options (as price insurance), and crop insurance. Stochastic cotton yields and prices are used to simulate a whole-farm financial statement for a 1,000 acre furrow irrigated cotton farm in the Texas Lower Rio Grande Valley under 16 combinations of risk management strategies. Analyses for risk-averse decision makers indicate that multiple irrigations are preferred. The benefits to purchasing put options increase with yields, as they are more beneficial when higher yields are expected from applying more irrigation applications. Crop insurance is strongly preferred at lower irrigation levels.cotton, crop insurance, irrigation, options, puts, risk, simulation, stochastic efficiency with respect to a function, Farm Management, Risk and Uncertainty, D81, Q12, Q15,

Team Poly Cup

This project involves the use of mechanical engineering expertise to develop, design, and create a functioning prototype of a collapsible coffee cup. The prototype is to be designed to the specifications given by Jason Blum, the project sponsor. Allowances may be given for design freedom as specified by Jason Blum. The goal of this project is to create a product which may replace the both the disposable coffee cups distributed at coffee shops as well as to create a product which may replace the traditional travel mug due to its increased portability. Team Poly Cup has worked throughout the year to design and test numerous locking mechanisms, water-tight seals, grips, and lids and have performed many calculations and created many prototypes to ensure the best design. We have expanded and finalized the design, completed a detailed cost analysis, finalized design verification, developed a manufacturing plan, and compiled a list of unique features that can be patented. In this report, we conclude the project, leaving Jason Blum with a completed prototype of the cup, as well as all documents needed for him to proceed with patenting and manufacturing of the cup

The Gribov Ambiguity for Maximal Abelian and Center Gauges in SU(2) Lattice Gauge Theory

We present results for the fundamental string tension in SU(2) lattice gauge theory after projection to maximal abelian and direct maximal center gauges. We generate 20 Gribov copies/configuration. Abelian and center projected string tensions slowly decrease as higher values of the gauge functionals are reached.Comment: 3 pages, latex, 1 postscript figure, presented at Lattice 2000(Topology and Vacuum

Design and development of novel screen-printed microelectrode and microbiosensor arrays fabricated using ultrafast pulsed laser ablation

© 2016 Elsevier B.V. All rights reserved. A new generic platform for the development of microbiosensors combining screen-printing and ultrafast pulsed laser technologies has been developed, characterised and evaluated. This new platform consists of a layer of screen-printed carbon ink containing the enzyme and mediator, covered with an insulating layer formed from a dielectric screen printed ink. Microholes were drilled through the insulated layer by ultrafast pulsed laser ablation to generate the microbiosensor array. The geometry of the microelectrode array was evaluated by optical microscopy, white light surface profiling and scanning electron microscopy. The electrochemical behaviour of the microelectrode array was characterised by cyclic voltammetry and compared with macroelectrodes. The analytical performance of the microbiosensor array was evaluated with external counter and reference electrodes for hydrogen peroxide and glucose determination showing linearity up to 4 mmol L-1 and 20 mmol L-1 (360 mg dL-1) respectively. The full screen printed three-electrode configuration shows linearity for glucose determination up to 20 mmol L-1 (360 mg dL-1). This study provides a new fabrication method for microelectrode and microbiosensor arrays capable for the first time to retain the activity of the enzymatic system after processing by pulse laser ablation

Orion Guidance and Control Ascent Abort Algorithm Design and Performance Results

During the ascent flight phase of NASA s Constellation Program, the Ares launch vehicle propels the Orion crew vehicle to an agreed to insertion target. If a failure occurs at any point in time during ascent then a system must be in place to abort the mission and return the crew to a safe landing with a high probability of success. To achieve continuous abort coverage one of two sets of effectors is used. Either the Launch Abort System (LAS), consisting of the Attitude Control Motor (ACM) and the Abort Motor (AM), or the Service Module (SM), consisting of SM Orion Main Engine (OME), Auxiliary (Aux) Jets, and Reaction Control System (RCS) jets, is used. The LAS effectors are used for aborts from liftoff through the first 30 seconds of second stage flight. The SM effectors are used from that point through Main Engine Cutoff (MECO). There are two distinct sets of Guidance and Control (G&C) algorithms that are designed to maximize the performance of these abort effectors. This paper will outline the necessary inputs to the G&C subsystem, the preliminary design of the G&C algorithms, the ability of the algorithms to predict what abort modes are achievable, and the resulting success of the abort system. Abort success will be measured against the Preliminary Design Review (PDR) abort performance metrics and overall performance will be reported. Finally, potential improvements to the G&C design will be discussed