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Lightweight Software Process Improvement Using Productivity and Sustainability Improvement Planning (PSIP)
Productivity and Sustainability Improvement Planning (PSIP) is a lightweight, iterative workflow that allows software development teams to identify development bottlenecks and track progress to overcome them. In this paper, we present an overview of PSIP and how it compares to other software process improvement (SPI) methodologies, and provide two case studies that describe how the use of PSIP led to successful improvements in team effectiveness and efficiency.
Vehicle lightweighting energy use impacts in U.S. light-duty vehicle fleet
In this article, we estimate the potential energy benefits of lightweighting the light-duty vehicle fleet from both vehicle manufacturing and use perspectives using plausible lightweight vehicle designs involving several alternative lightweight materials, low- and high-end estimates of vehicle manufacturing energy, conventional and alternative powertrains, and two different market penetration scenarios for alternative powertrain light-duty vehicles at the fleet level. Cumulative life cycle energy savings (through 2050) across the nine material scenarios based on the conventional powertrain in the U.S. vehicle fleet range from -29 to 94 billion GJ, with the greatest savings achieved by multi-material vehicles that select different lightweight materials to meet specific design purposes. Lightweighting alternative-powertrain vehicles could produce significant energy savings in the U.S. vehicle fleet, although their improved powertrain efficiencies lessen the energy savings opportunities for lightweighting. A maximum level of cumulative energy savings of lightweighting the U.S. light-duty vehicle through 2050 is estimated to be 66.1billion GJ under the conventional-vehicle dominated business-as-usual penetration scenario.
Vehicle Lightweighting: 40% and 45% Weight Savings Analysis: Technical Cost Modeling for Vehicle Lightweighting
The U.S. Department of Energy’s Vehicle Technologies Office, Materials area commissioned a study to model and assess manufacturing economics of alternative design and production strategies for a series of lightweight vehicle concepts. The strategic targets were a 40% and a 45% mass reduction relative to a standard North American midsize passenger sedan at an effective cost of $3.42 per pound (lb) saved. The baseline vehicle was an average of several available vehicles in this class. Mass and cost breakdowns from several sources were used, including original equipment manufacturers’ (OEMs’) input through U.S. Department of Energy’s Vehicle Technologies Office programs and public presentations, A2Mac1 LLC’s teardown information, Lotus Engineering Limited and FEV, Inc. breakdowns in their respective lightweighting studies, and IBIS Associates, Inc.’s decades of experience in automotive lightweighting and materials substitution analyses. Information on lightweighting strategies in this analysis came from these same sources and the ongoing U.S. Department of Energy-funded Vehma International of America, Inc. /Ford Motor Company Multi-Material Lightweight Prototype Vehicle Demonstration Project, the Aluminum Association Transportation Group, and many United States Council for Automotive Research’s/United States Automotive Materials Partnership LLC lightweight materials programs.
Energy and emissions saving potential of additive manufacturing: the case of lightweight aircraft components
Additive manufacturing (AM) holds great potential for improving materials efficiency, reducing life-cycle impacts, and enabling greater engineering functionality compared to conventional manufacturing (CM), and AM has been increasingly adopted by aircraft component manufacturers for lightweight, cost-effective designs. This study estimates the net changes in life-cycle primary energy and greenhouse gas emissions associated with AM technologies for lightweight metallic aircraft components through the year 2050, to shed light on the environmental benefits of a shift from CM to AM processes in the U.S. aircraft industry. A systems modeling framework is presented, with integrates engineering criteria, life-cycle environmental data, aircraft fleet stock and fuel use models under different AM adoption scenarios. Estimated fleet-wide life-cycle primary energy savings at most reach 70-173 million GJ/year in 2050, with cumulative savings of 1.2–2.8 billion GJ. Associated cumulative GHG emission reductions were estimated at 92.1–215.0 million metric tons. In addition, thousands of tons of aluminum, titanium and nickel alloys could be potentially saved per year in 2050. The results indicate a significant role of AM technologies in helping society meet its long-term energy use and GHG emissions reduction goals, and highlight barriers and opportunities for AM adoption for the aircraft industry.
Pathways to formulate lightweight and ultra-lightweight 3D printable cementitious composites
Here, this paper studies the pathways to formulate lightweight and ultra-lightweight 3D printable cementitious composites. A hybrid approach was proposed by combining the advantages of traditional chemical-induced foaming (foaming approach) and lightweight particulate inclusions (synthetic foam approach). A comprehensive experimental program was conducted to evaluate the effects of foaming agents and fly ash cenosphere (FAC) on the printability, microstructure, mechanical and thermal properties of 3D printed samples. The results showed that the hybrid approach could produce a mixture with a density as low as 470 kg/m 3 while ensuring good flowability and buildability owing to the lubricating effect of foaming and supporting skeleton formed by FAC. In addition, a three-step homogenization procedure was also developed to predict the effective elastic modulus and thermal conductivity of 3D printable cementitious composites and cementitious foam. The findings of the study highlighted the effectiveness of the hybrid approach in formulating 3D printable ultra-lightweight cementitious composites in thermal insulation and acoustic applications.
Lightweighting Impacts on Fuel Economy, Cost, and Component Losses
Abstract not provided
Off-spec fly ash-based lightweight aggregate properties and their influence on the fresh, mechanical, and hydration properties of lightweight concrete: A comparative study
An off-spec fly ash-based spherical lightweight aggregate (LWA), designated as Spherical Porous Reactive Aggregate (SPoRA), was manufactured through a lab pilot-scale production and its engineering properties, including specific gravity, dry rodded unit weight, water absorption, mechanical performance, and pore structure, were evaluated. Using SPoRA, lightweight concrete (LWC) samples were made and their fresh, mechanical, and hydration properties were assessed and compared with LWC samples made using two commercial LWA available in the US market. The results indicated that fine and coarse SPoRA had 72 h water absorption capacities of 16.4 % and 20.9 %, respectively, which were higher than that of the two commercial LWAs. Higher saturated surface dry specific gravity of SPoRA compared to commercial LWAs led to a higher fresh density for the corresponding LWC. Using X-ray computed tomography, large spherical type pores were observed in SPoRA similar to those in the commercial slate-based LWA. Additionally, the pore size distribution of SPoRA, characterized by a dynamic vapor sorption analyzer, indicated that more than 97 % of the pores had diameters greater than 50 nm. SPoRA’s average bulk crushing strength was 6.8 MPa which was smaller than commercial LWA and was potentially attributed to the differences in manufacturing processes. Nonetheless, SPoRA LWC with 28 days compressive strength of 29 MPa passed the ASTM C330 requirement and had a comparable strength with LWC prepared with the commercial LWAs indicating lesser importance for the LWA strength. SPoRA LWC had a flowability of 5 % compared to LWC prepared with commercial LWAs having flowability of 18 %. This observation was potentially related to the fluxing agent used in the SPoRA production. SPoRA had a 70 % degree of hydration at 12 days which was comparable with that of LWC prepared with commercial LWA.
Argobots: A Lightweight Low-Level Threading and Tasking Framework
In the past few decades, a number of user-level threading and tasking models have been proposed in the literature to address the shortcomings of OS-level threads, primarily with respect to cost and flexibility. Current state-of-the-art user-level threading and tasking models, however, are either too specific to applications or architectures or are not as powerful or flexible. In this paper, we present Argobots, a lightweight, low-level threading and tasking framework that is designed as a portable and performant substrate for high-level programming models or runtime systems. Argobots offers a carefully designed execution model that balances generality of functionality with providing a rich set of controls to allow specialization by the user or high-level programming model. We describe the design, implementation, and optimization of Argobots and present integrations with three example high-level models: OpenMP, MPI, and co-located I/O service. Evaluations show that (1) Argobots outperforms existing generic threading runtimes; (2) our OpenMP runtime offers more efficient interoperability capabilities than production OpenMP runtimes do; (3) when MPI interoperates with Argobots instead of Pthreads, it enjoys reduced synchronization costs and better latency hiding capabilities; and (4) I/O service with Argobots reduces interference with co-located applications, achieving performance competitive with that of the Pthreads version.
Lightweight Mechanical Metamaterials with Tunable Negative Thermal Expansion
Ice floating on water is a great manifestation of negative thermal expansion (NTE) in nature. The limited examples of natural materials possessing NTE have stimulated research on engineered structures. Previous studies on NTE structures were mostly focused on theoretical design with limited experimental demonstration in two-dimensional planar geometries. Here, in this work, aided with multimaterial projection microstereolithography, we experimentally fabricate lightweight multimaterial lattices that exhibit significant negative thermal expansion in three directions and over a temperature range of 170 degrees. Such NTE is induced by the structural interaction of material components with distinct thermal expansion coefficients. The NTE can be tuned over a large range by varying the thermal expansion coefficient difference between constituent beams and geometrical arrangements. Our experimental results match qualitatively with a simple scaling law and quantitatively with computational models.
Porting the Kitten Lightweight Kernel Operating System to RISC-V
Hardware design in high-performance computing (HPC) is often highly experimental. Exploring new designs is difficult and time-consuming, requiring lengthy vendor cooperation. RISC-V is an open-source processor ISA that improves the accessibility of chip design, including the ability to do hardware/software co-design using open-source hardware and tools. Co-design allows design decisions to easily flow across the hardware/software boundary and influence future design ideas. However, new hardware designs require corresponding software to drive and test them. Conventional operating systems like Linux are massively complex and modification is time-prohibitive. In this paper, we describe our port of the Kitten lightweight kernel operating system to RISC-V in order to provide an alternative to Linux for conducting co-design research. Kitten's small code base and simple resource management policies are well matched for quickly exploring new hardware ideas that may require radical operating system modifications and restructuring. Our evaluation shows that Kitten on RISC-V is functional and provides similar performance to Linux for single-core benchmarks. This provides a solid foundation for using Kitten in future co-design research involving RISC-V.
The Lightweight Distributed Metric Service: A Scalable Infrastructure for Continuous Monitoring of Large Scale Computing Systems and Applications.
Abstract not provided.
Improving Application Resilience to Memory Errors with Lightweight Compression.
Abstract not provided.
Lightweight hollow rooftop mirrors for stabilized interferometry
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Lightweight Materials - Carbon Fiber and Polymer Composites, Integrated Computational Materials Engineering (ICME) Predictive Tools Development for Low-Cost Carbon Fiber for Lightweight Vehicles (University of Virginia) (Final Report)
This project aimed to develop low-cost alternative precursors and processing techniques through the implementation of an integrated computational materials engineering (ICME) framework to evaluate precursor conversion kinetics. Once established, this framework was then used to down-select precursors for laboratory- and pilot-scale production to validate resulting carbon fiber (CF) material properties and process cost-savings. The two most promising approaches to reduce the cost of CFs were to (1) use new low-cost precursors and (2) reduce the energy requirements of CF processing. These approaches were investigated over the course of three phases of work, spanning 3.5 years. This report describes the overall project objectives, approach, and the key accomplishments in each phase.
A method for determining optimal electric range by considering electric vehicle lightweighting on perceived ownership cost
The limited driving range due to high costs and low energy densities of batteries constraints the battery electric vehicle (BEV) market growth. Lightweighting in theory can reduce energy consumption rate and extend the driving range. The knowledge gap is to quantitatively link the cost-effectiveness of light-weight technologies with range extension and consumer acceptance of BEVs. In this study, a physics-based energy consumption model of BEVs is constructed and associated with a statistics-based model on the basis of travel surveys. A perceived cost of ownership (PCO) is then developed by adding intangible costs to traditional total cost of ownership models. We estimate, at the disaggregate vehicle model and driver level and the aggregate market level, 1) the extended range due to lightweighting for a given battery size; and 2) the optimal electric range based on lightweighting decisions. The cost-effectiveness of lightweighting for BEV range extension is found to vary with income-dependent daily range limitation value, driving patterns and lightweighting technology costs. In general, adopting lightweighting in BEVs is more cost-effective for consumers with higher daily limitation value, as well as for those with higher driving intensity or suitable daily driving patterns. When the lightweighting involves a higher vehicle production cost, less lightweighting could reduce the overall PCO for BEV owners. 4 of the selected top ten BEV models are found to benefit from additional 2.09%–4.45% lightweighting. Finally, the method built in this study can guide automakers in planning R&D investments in battery and lightweighting technologies.
Reducing supply chain energy use in next-generation vehicle lightweighting
Vehicle lightweighting reduces the amount of fuel consumed in a vehicle's use phase, but depending on what lightweight materials replace the conventional materials, and in what amounts, the manufacturing energy may increase or decrease. For carbon fiber reinforced polymer (CFRP), a next-generation lightweighting material, the increase in vehicle manufacturing energy is greater than the fuel savings, resulting in a net increase in energy consumption over a vehicle's manufacturing and use relative to a standard non-lightweighted car. [1] This work explores ways to reduce the supply chain energy of CFRP lightweighted vehicles through alternative production technologies and energy efficiency improvements. The objective is to determine if CFRP can offer energy savings comparable to or greater than aluminum, a conventional lightweighting material. Results of this analysis can be used to inform additional research and development efforts in CFRP production and future directions in lightweight vehicle production. The CFRP supply chain is modeled using the Material Flows through Industry (MFI) scenario modeling tool, which calculates 'mine to materials' energy consumption, material inventories and greenhouse gas emissions for industrial supply chains. In this analysis, the MFI tool is used to model the supply chains of two lightweighted vehicles, an aluminum intensive vehicle (AIV) and a carbon fiber intensive vehicle (CFV), under several manufacturing scenarios. Vehicle specifications are given in [1]. Scenarios investigated cover alternative carbon fiber (CF) feedstocks and energy efficiency improvements at various points in the vehicle supply chains. The alternative CF feedstocks are polyacrylonitrile, lignin and petroleum-derived mesophase pitch. Scenarios in which the energy efficiency of CF and CFRP production increases are explored using sector efficiency potential values, which quantify the reduction in energy consumption achievable when process equipment is upgraded to the most efficient available. Preliminary analyses indicate that producing CF from lignin instead of polyacrylonitrile, the most commonly used feedstock, reduces energy consumption in the CFRP supply chain by 7.5%, and that implementing energy efficient process equipment produces an additional 8% reduction. Final results will show if these potential reductions are sufficient to make the CFV energy savings comparable with AIV energy savings. [1] Das, S., Graziano, D., Upadhyayula, V. K., Masanet, E., Riddle, M., & Cresko, J. (2016). Vehicle lightweighting energy use impacts in US light-duty vehicle fleet. Sustainable Materials and Technologies, 8, 5-13.
Upgrading the Center for Lightweighting Automotive Materials and Processing - a GATE Center of Excellence at the University of Michigan-Dearborn (Final Technical Report: September 2005-August 2021)
The Center for Lightweighting Materials and Processing (CLAMP) was established in September 1998 with a grant from the Department of Energy’s Graduate Automotive Technology Education (GATE) program. The center received the second round of GATE grant in 2005 under the title “Upgrading the Center for Lightweighting Automotive Materials and Processing”. Using the two grants, the Center has successfully created 10 graduate level courses on lightweight automotive materials, integrated them into master’s and PhD programs in Automotive Systems Engineering, and offered them regularly to the graduate students in the program. In addition, the Center has created a web-based lightweight automotive materials database, conducted research on lightweight automotive materials and organized seminars/symposia on lightweight automotive materials for both academia and industry. The faculty involved with the Center has conducted research on a variety of topics related to design, testing, characterization and processing of lightweight materials for automotive applications and have received numerous research grants from automotive companies and government agencies to support their research. The materials considered included advanced steels, light alloys (aluminum, magnesium and titanium) and fiber reinforced polymer composites. In some of these research projects, CLAMP faculty have collaborated with industry partners and students have used the research facilities at industry locations. The specific objectives of the project during the current funding period (2005 – 2012) were as follows: (1) develop new graduate courses and incorporate them in the automotive systems engineering curriculum (2) improve and update two existing courses on automotive materials and processing (3) upgrade the laboratory facilities used by graduate students to conduct research (4) expand the Lightweight Automotive Materials Database to include additional materials, design case studies and make it more accessible to outside users (5) provide support to graduate students for conducting research on lightweight automotive materials and structures (6) provide industry/university interaction through a graduate certificate program on automotive materials and technology idea exchange through focused seminars and symposia on automotive materials.