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At least 235 records · Page 13

ECOSYSTEM IMPACTS OF GEOENGINEERING: A Review for Developing a Science Plan

Geoengineering methods are intended to reduce the magnitude of climate change. Climate change in some regions is already having demonstrable effects on ecosystem structure and functioning. Two different types of geoengineering activities have been proposed: carbon dioxide removal (CDR), which includes a range of engineered and biological processes to remove carbon dioxide (CO2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), whereby a small percentage of sunlight is reflected back into space to offset warming from greenhouse gases. In this review, we evaluate some of the possible impacts of CDR and SRM on the physical climate and their subsequent influence on ecosystems, including the risks and uncertainties associated with new kinds of purposeful perturbations to Earth. Specifically, we find evidence that, if implemented successfully, some CDR methods and continue use of some SRM methods) could alleviate some of the deleterious ecosystem impacts associated with climate changes that might occur in the foreseeable future.

Geoengineering, Ecosystems, Climate Change, Carbon↗

Integrating tactical planning, operational planning and scheduling using data-driven feasibility analysis

Supply chain operations and scheduling are well-studied problems in the literature. Although these problems are related, they are often solved sequentially. This uncoordinated approach usually leads to sub-optimal solutions. Here this paper proposes a methodology for integrating scheduling operations into the supply chain network, motivated by the available enterprise data, and feasibility analysis. Existing literature on integrated models for addressing the supply chain is reviewed and classified. Then the mathematical model formulation for each level is discussed, after which the proposed data-driven integrated framework is described. The methodology is tested on two different case studies of varying dimensions. For each case study, the solution solves a multi-objective problem with the overall aim of an optimal solution that is robust towards achieving optimal cost while keeping customer satisfaction in mind.

42 ENGINEERING↗

Perspectives on the FESAC transformative enabling capabilities: Priorities, plans, and Status

In early 2017, the Fusion Energy Sciences Advisory Committee (FESAC), an advisory committee to the United States Department of Energy, was charged with identifying transformative enabling capabilities (TECs) “that could promote efficient advance toward fusion energy, building on burning plasma science and technology.” A subcommittee with broad expertise was formed and sought feedback from scientific experts, including experts from outside the fusion community. Three workshops were conducted, and a report was approved by FESAC in 2018 that identified four of the “most promising” TECs: advanced algorithms, high-critical-temperature superconductors, advanced materials and manufacturing, and novel technologies for tritium fuel cycle control. In addition, one “promising” TEC was identified: fast flowing liquid metal plasma-facing components. This paper will give details on the promising TECs and an overview on considerations of these TECs in the United States since the publication of the report.

Lumsdaine, Arnold↗

A GPU-based Approach for Path Planning Optimization via Travel Length Reduction

Typically, before constructing an object with an additive manufacturing system, the 3D object must be sent through a process called slicing. Slicing converts a 3D object commonly in the form of an STL file into a set of layers by horizontally intersecting a plane with the object at various heights. At each height, called a layer, multiple 2D polygons can be generated. Each polygon represents a boundary for solid geometry and is called an island. Each island is then comprised of multiple path types in an attempt to optimally fill the polygon. To move between each island and each islands’ paths, travels are inserted. Travels are simply motion by the system to move from one area of construction to another. Travels do not contribute to the construction of the object, and so, are considered wasted motion. In large-scale additive manufacturing, objects can be quite large and the distance between islands can be large as well. As a result, these travels can waste a significant amount of time. Ideally, travels would be as short as possible, however, computing global minimal travel paths is computationally expensive. To combat this problem, researchers at Oak Ridge National Lab developed a GPU-based approach to travel insertion based on a unique factoradic representation. This representation was then utilized by the GPU to solve the Traveling Salesman Problem (TSP). This algorithm was able to compute global minimal travel paths quickly resulting in faster object construction. A general investigation was also carried out to determine when a GPU vs CPU implementation would be beneficial.

Borish, Michael↗

Higgs properties in the fourth-generation MSSM: Boosted signals over the three-generation plan

The generalization of the minimal supersymmetric standard model (MSSM) to the case of four chiral fermion generations (4GMSSM) can lead to significant changes in the phenomenology of the otherwise familiar Higgs sector. In most of the 3GMSSM parameter space, the lighter CP-even h is {approx}115-125 GeV and mostly standard model-like while H, A, H{sup {+-}} are all relatively heavy. Furthermore, the ratio of Higgs vacuum expectation values, tan{beta}, is relatively unconstrained. In contrast to this, in the 4GMSSM, heavy fourth-generation fermion loops drive the masses of h, H, H{sup {+-}} to large values while the CP-odd boson, A, can remain relatively light and tan{beta} is restricted to the range 1/2 < or approx. tan{beta} < or approx. 2 due to perturbativity requirements on Yukawa couplings. We explore this scenario in some detail, concentrating on the collider signatures of the light CP-odd Higgs at both the Tevatron and LHC. We find that while gg{yields}A may lead to a potential signal in the {tau}{sup +}{tau}{sup -} channel at the LHC, A might first be observed in the {gamma}{gamma} channel due to a highly loop-enhanced cross section that can be more than an order of magnitude greater than that of a SM Higgs for A masses of {approx}100-150 GeV and tan{beta}<1. We find that the CP-even states h, H are highly mixed and can have atypical branching fractions. Precision electroweak constraints, particularly for the light A parameter space region, are examined in detail.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

A plan to revitalize the domestic superconducting radio-frequency industry

Superconducting radio-frequency (SRF) cavities are essential building blocks of modern particle accelerators for scientific research, and they offer unique capabilities that could be transformative for commercial applications. Growth of the domestic SRF industry in North America has faced several challenges over the past decades, as most of the international demand for cavities was supplied by European vendors. This contribution provides a brief review of the domestic industrial vendor space, an outlook of the global demand for SRF cavities and an outline of the challenges leading to this supply chain deficiency. One of the main challenges towards establishing a robust domestic SRF industry has been the large uncertainty in the demand. Meanwhile, research and development activities to raise technical readiness of SRF accelerators for industrial use have continued and several potential markets are emerging that may offer a consistent and growing demand for SRF cavities. Finally, reasons and means of establishing and sustaining competitive domestic suppliers are described.

Accelerator Physics↗

ALDX Mission Assurance Plan and Quality Plan

This document describes how ALDX assures successful mission delivery, via nurturing essential scientific and computational capabilities in our staff, negotiating and delivering upon milestones, and ensuring a safe, secure, and productive work environment. The document also describes how we manage and minimize different types of risks, ranging from risks associated with completing essential mission tasks, to risks in safety and security in our organization, as discussed in the Risk Register/Heat Map. It also describes how ALDX assures Quality in its work.

99 GENERAL AND MISCELLANEOUS↗