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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Global meta-analysis of published river bank erosion and migration rates

This dataset is a compilation of 993 measurements of riverbank erosion or migration rates from 336 rivers and streams compiled from 169 published English language studies. The dataset spans rivers across latitudes ranging from 46 deg south to 71 deg north. The rivers range in drainage area from 0.6 to 3 million square kilometers. If provided in a published study, recorded channel width, river drainage area, and sediment load and/or yield were summarized. In the absence of these ancillary data from the original source, this data was compiled from other published studies, global and regional datasets, or measured from Google Earth images. The dataset also provides information on whether the rates were measured at an individual river bend or represent reach-based averages, as well as, whether the river is single or multi-threaded.Revisions 2023 January updateAdded 72 new erosion measurements. Dropped 10 records that did not have mean erosion values.“DrainageArea(km^2)_rabpro” added“DrainageArea(km^2)” – updated to only include published drainage area and values obtained from sources other than the rabpro analysis.“River_slope_pub” added to provide river slope values provided in the published erosion study or other source listed in the “Slope Reference” field“RiverSlope_Lin” added“FLO1K_MonthlyMax_LT” and “FLO1K_MontlyMax_PoR” added“KG_Zone” added from Köppen-geiger climate classification based on Beck et al. 2018

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

The LAKE model input dataset for three Arctic lakes

This dataset contains meteorological data collected for three Arctic lakes and compiled to satisfy input requirements of the LAKE 2.0 model. The dataset was generated to act as a benchmarking dataset for future model-data inter-comparisons. The LAKE 2.0 model simulates temperatures within the water later and the sedimentary layer of a lake. The LAKE2.0. is an open-source code and available to download via this weblike http://tesla.parallel.ru/Viktor/LAKE/-/wikis/LAKE-model (last visit July 14, 2021). The meteorological data are required to simulate the surface energy balance at the surface of a lake. This dataset includes a compilation of the meteorological data pulled from multiple data streams, including National Oceanic and Atmospheric Administration (NOAA) climate data, Circumarctic Lakes Observation Network (CALON) data, and the United States Geological Survey (USGS) data. The data were compiled for three Arctic lakes: FoxDen (66.55877, -164.45670), Atqasuk (70.452497, -156.951984), and Toolik (68.63150, -149.60740). Each meteorological data is in comma-delimited format (file extension ‘.dat’) and includes eight columns: Temperature [K], Pressure [Pa], longwave downward radiation [W/m2], shortwave downward radiation [W/m2], “U” wind speed [m/s], ”V” wind speed [m/s], humidity [kg/kg], precipitation [m/s]. In addition to the meteorological data file, we included setup and driver files. The Toolik lake is the deepest out of three lakes and has inflowing and outflowing groundwater data. InflowOutflowREADME.txt has more information about inflow and outflow flies. The other two lakes are much shallower and modeled as a closed system (i.e. no water inflow or outflow).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Community Based Data of Uranium Adsorption onto Quartz

This data upload includes a compilation of experiments for quantifying uranium adsorption onto quartz. The provided .csv file has been compiled from the literature in a findable, accessible, interoperable, reusable (FAIR) data format. This was accomplished using the Lawrence Livermore National Laboratory Surface Complexation Database Converter (SCDC) code written in the R programming language (free licensing available at https://ipo.llnl.gov/technologies/software/llnl-surface-complexation-database-converter-scdc). This constitutes all current data compiled on uranium-quartz interactions in the L-SCIE (LLNL Surface Complexation/Ion Exchange) database (as of 02/28/2022). This data was used to develop surface complexation models that fit the global community dataset (https://doi.org/10.1021/acs.est.1c07109). The FAIR-formatted dataset also enables the implementation of alternative machine-learning approaches that can be explored in the future.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Linking resource availability to pantropical forest canopy resistance and resilience to cyclone disturbance

Statement of purpose: Tropical cyclones are intensifying and occurring at higher latitudes in recent decades, but the mechanisms underpinning the resistance (ability to withstand disturbance-induced change) and resilience (pace of return to pre-disturbance reference values) of tropical forests to cyclones remains largely unexplored at the pantropical scale. We conducted a meta-analysis to investigate the role of soil resource availability (i.e., total soil phosphorus concentration) in mediating site-level forest canopy resistance and resilience to cyclones pan-tropically. We evaluated cyclone-induced and post-cyclone litterfall mass (g/m2/day), phosphorus (P) and nitrogen (N) fluxes (mg/m2/day), as well as concentrations (mg/g) across 73 case studies in Australia, Guadeloupe, Hawaii, Mexico, Puerto Rico, and Taiwan. The dataset zip file includes three data and two metadata files: - The compiled Litterfall Mass Flux data from tropical forests across the globe prior to and after varying tropical cyclone disturbances are provided in Litterfall_Mass.csv. This data file also includes site location, geographical characteristics, elevation, soil phosphorus concentration, geology, and several variables related to each tropical cyclone disturbance. - The compiled Litterfall Nitrogen and Phosphorus Flux data from tropical forests across the globe prior to and after varying tropical cyclone disturbances are provided in Litterfall_Nutrients.csv. This data file also includes site location, geographical characteristics, elevation, soil phosphorus concentration, geology, and several variables related to each tropical cyclone disturbance. - Tropical cyclone track data compiled from HURDAT2 and IBTrACS databases and used as input in the HURRECON model (https://github.com/hurrecon-model/HurreconR) to generate wind data is provided in hurdat2-1851-2019-052520.txt. - The metadata file (Metadata_Meta-analysis_Litterfall-Mass.pdf) has the complete information on each variable included in the Litterfall_Mass.csv dataset, the data sources, and data processing information. - The metadata file (Metadata_Meta-analysis_Litterfall-Nutrients.pdf) has the complete information on each variable included in the Litterfall_Nutrients.csv dataset, the data sources, and data processing information.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Compositional Dataflow Via Abstract Transition Systems

Despite decades of research and development of dataflow analyses within dozens of different compiler infrastructures, analysis of real programs is intractable in practice. The reason is that although a single research group is equipped to model a single well-defined aspect of application behavior, application developers use a very wide range of abstractions and coding techniques within a single application. Since to analyze even a single application all of its complexities must be modeled, researchers must combine analyses from multiple groups into comprehensive analysis frameworks such as OpenAnalysis or LLVM. Analysis composition is expensive in practice, requiring development effort that is quadratic in the number of analyses as well as tight inter-group coordination to maintain consistent APIs to each other’s symbolic abstractions. This paper proposes an approach to building compiler analysis frameworks that simplifies the composition of independently-developed analyses. It formalizes the operation of dataflow analyses in a way that simplifies reasoning about various types of analysis composition. Further, it defines a portable abstraction that can represent the results of many real analyses, making it possible for different analyses to leverage each other’s results with no knowledge of their APIs or internal abstractions and without any coordination between the groups that developed them. We have developed the Fuse compositional analysis framework based on this abstraction, and integrated it in the ROSE [15] compilation system. Our experience is that this approach greatly simplifies composition of program analyses, making it easy to tailor different combinations of program analyses to different input programs.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2013

Updated Subsurface Data Base For Bear Creek Valley, Chestnut Ridge, And Parts Of Bethel Valley On The U.S. Department of Energy Oak Ridge Reservation

This document represents a compilation of location, construction, and hydrologic information relating to boreholes, groundwater monitoring wells, and surface water locations that have been installed/established at the Y-12 National Security Complex (Y-12) through August 2013. To date, a total of 1422 boreholes and wells have been installed in and around the Y-12 area. Of those, 835 existing boreholes and wells continue to be utilized for groundwater monitoring programs, research, remedial investigations, plume characterization and delineation studies, and various other hydrogeologic endeavors. In addition, 215 surface water locations, such as rivers, streams, seeps, springs, lakes, ponds, and building sumps are included in this database. General data about boreholes and wells included in the database are survey coordinates, survey system, elevations, alternative names and well status. Surface water location information (Appendix I) includes name, alias, functional area, northing and easting coordinates, survey system, map number and sampling history. Tabulated construction data include total depth, completion method, borehole diameter, casing and screen materials, casing and screen diameters, casing and screen depths, filter pack depths, open-hole intervals, and open-hole diameters. Hydrogeological data summarized in this document include the aquifer monitored by the completion interval, depth to weathered and fresh bedrock, formations penetrated, well sampling history, and whether rock core and geophysical logs were obtained. This document (which is the sixth revision to Y/TS–881 and the ninth overall update of a previous compilation) is published on a regular basis by the Y-12 Groundwater Protection Program (GWPP), which serves as custodian of drilling records and well construction data for the network of wells and other groundwater monitoring stations at Y-12. The tabulations in this database are arranged in appendices of like information. An example application of the data compiled in this document would be the evaluation of the suitability of wells for continued use in groundwater investigations and monitoring studies. Other uses may include: the siting of hydrogeological characterization activities, background evaluations of sites prior to initiation of new drilling activities, and hydrogeological review of selected sites prior to the initiation of remedial actions or new construction activity. Existing boreholes, wells, and surface water locations are presented on a series of maps (Appendix K). Boreholes and wells that have been plugged and abandoned, destroyed, could not be located, or otherwise are of unknown status/condition appear on a second series of maps of identical coverage (Appendix L).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Comparison of the Amanzi Model against Analytical Solutions and the FEHM Model

This file documents Amanzi code verification of flow simulations for three selected cases: (1) an infinite strip aquifer embedded between two other aquifers, (2) a heterogeneous cylinder (or disc in 2D case) embedded in a background aquifer, and (3) uniform aquifers in bounded domains with fixed heads at the upper- and down-stream directions and no-flow at lateral boundaries. The original FORTRAN codes that solve the analytical solutions for cases (1) and (2) were obtained from Greg Ruskauf. Two modifications were made for compilation on Linux systems: (a) The keyword ‘mode’ in OPEN statements was removed because it is not standard, and (b) variables in COMMON blocks were re-arranged to eliminate a warning message (padding of additional 4 bytes). These codes were compiled using the gfortran compiler on the Linux environment. Note that these analytical solutions were derived for two-dimensional problems only, and therefore in numerical simulations, we used three-dimensional domains with unit thickness for comparison.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Functional Programming in Computer Science

We explore functional programming through a 16-week internship at Los Alamos National Laboratory. Functional programming is a branch of computer science that has exploded in popularity over the past decade due to its high-level syntax, ease of parallelization, and abundant applications. First, we summarize functional programming by listing the advantages of functional programming languages over the usual imperative languages, and we introduce the concept of parsing. Second, we discuss the importance of lambda calculus in the theory of functional programming. Lambda calculus was invented by Alonzo Church in the 1930s to formalize the concept of effective computability, and every functional language is essentially some implementation of lambda calculus. Finally, we display the lasting products of the internship: additions to a compiler and runtime system for the pure functional language STG, including both a set of tests that indicate the validity of updates to the compiler and a compiler pass that checks for illegal instances of duplicate names.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Recovery Act: An Integrated Experimental and Numerical Study: Developing a Reaction Transport Model that Couples Chemical Reactions of Mineral Dissolution/Precipitation with Spatial and Temporal Flow Variations.

A total of 12 publications and 23 abstracts were produced as a result of this study. In particular, the compilation of a thermodynamic database utilizing consistent, current thermodynamic data is a major step toward accurately modeling multi-phase fluid interactions with solids. Existing databases designed for aqueous fluids did not mesh well with existing solid phase databases. Addition of a second liquid phase (CO2) magnifies the inconsistencies between aqueous and solid thermodynamic databases. Overall, the combination of high temperature and pressure lab studies (task 1), using a purpose built apparatus, and solid characterization (task 2), using XRCT and more developed technologies, allowed observation of dissolution and precipitation processes under CO2 reservoir conditions. These observations were combined with results from PIV experiments on multi-phase fluids (task 3) in typical flow path geometries. The results of the tasks 1, 2, and 3 were compiled and integrated into numerical models utilizing Lattice-Boltzmann simulations (task 4) to realistically model the physical processes and were ultimately folded into TOUGH2 code for reservoir scale modeling (task 5). Compilation of the thermodynamic database assisted comparisons to PIV experiments (Task 3) and greatly improved Lattice Boltzmann (Task 4) and TOUGH2 simulations (Task 5). PIV (Task 3) and experimental apparatus (Task 1) have identified problem areas in TOUGHREACT code. Additional lab experiments and coding work has been integrated into an improved numerical modeling code.

15 GEOTHERMAL ENERGY↗
DOE OSTI2017

Milestone Completion Report WBS 1.3.5.05 ECP/VTK-m FY17Q2 [MS-17/01] Better Dynamic Types Design SDA05-1

The FY17Q2 milestone of the ECP/VTK-m project, which is the first milestone, includes the completion of design documents for the introduction of virtual methods into the VTK-m framework. Specifically, the ability from within the code of a device (e.g. GPU or Xeon Phi) to jump to a virtual method specified at run time. This change will enable us to drastically reduce the compile time and the executable code size for the VTK-m library. Our first design introduced the idea of adding virtual functions to classes that are used during algorithm execution. (Virtual methods were previously banned from the so called execution environment.) The design was straightforward. VTK-m already has the generic concepts of an “array handle” that provides a uniform interface to memory of different structures and an “array portal” that provides generic access to said memory. These array handles and portals use C++ templating to adjust them to different memory structures. This composition provides a powerful ability to adapt to data sources, but requires knowing static types. The proposed design creates a template specialization of an array portal that decorates another array handle while hiding its type. In this way we can wrap any type of static array handle and then feed it to a single compiled instance of a function. The second design focused on the mechanics of implementing virtual methods on parallel devices with a focus on CUDA. Our initial experiments on CUDA showed a very large overhead for using virtual C++ classes with virtual methods, the standard approach. Instead, we are using an alternate method provided by C that uses function pointers. With the completion of this milestone, we are able to move to the implementation of objects with virtual (like) methods. The upshot will be much faster compile times and much smaller library/executable sizes.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Evaluation of CHO Benchmarks on the Arria 10 FPGA using Intel FPGA SDK for OpenCL

The OpenCL standard is an open programming model for accelerating algorithms on heterogeneous computing system. OpenCL extends the C-based programming language for developing portable codes on different platforms such as CPU, Graphics processing units (GPUs), Digital Signal Processors (DSPs) and Field Programmable Gate Arrays (FPGAs). The Intel FPGA SDK for OpenCL is a suite of tools that allows developers to abstract away the complex FPGA-based development flow for a high-level software development flow. Users can focus on the design of hardware-accelerated kernel functions in OpenCL and then direct the tools to generate the low-level FPGA implementations. The approach makes the FPGA-based development more accessible to software users as the needs for hybrid computing using CPUs and FPGAs are increasing. It can also significantly reduce the hardware development time as users can evaluate different ideas with high-level language without deep FPGA domain knowledge. Benchmarking of OpenCL-based framework is an effective way for analyzing the performance of system by studying the execution of the benchmark applications. CHO is a suite of benchmark applications that provides support for OpenCL [1]. The authors presented CHO as an OpenCL port of the CHStone benchmark. Using Altera OpenCL (AOCL) compiler to synthesize the benchmark applications, they listed the resource usage and performance of each kernel that can be successfully synthesized by the compiler. In this report, we evaluate the resource usage and performance of the CHO benchmark applications using the Intel FPGA SDK for OpenCL and Nallatech 385A FPGA board that features an Arria 10 FPGA device. The focus of the report is to have a better understanding of the resource usage and performance of the kernel implementations using Arria-10 FPGA devices compared to Stratix-5 FPGA devices. In addition, we also gain knowledge about the limitations of the current compiler when it fails to synthesize a benchmark application.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Parallelization of a Proxy Transport App Using ComputeCPP and SYCL

This document details the attempts to parallelize a multi-group Monte Carlo proxy app using SYCL and the ComputeCPP Community Edition compiler. SYCL is a standard set by the Khronos Group and is described as a, “cross-platform abstraction layer that builds on the underlying concepts, portability and efficiency of OpenCL that enables code for heterogeneous processors to be written in a “single-source” style using completely standard C++.” ComputeCpp Community Edition (CE) is a heterogeneous parallel programming platform that provides a conformant implementation of the SYCL™ 1.2.1 Khronos specification. ComputeCPP provides a compiler and an SDK containing a build system to improve the usability of the compiler. The supported OpenCL 1.2 platforms for ComputeCpp are AMD® and Intel®, with experimental support for PTX which is used on Nvidia graphics cards as well as experimental support for ARM chips. All testing reported in this document was done on the Darwin computer cluster using an Nvidia GTX Titan X graphics card. Since ComputeCPP does not support using this card with OpenCL, ComputeCPP’s experimental PTX64 bit-code generation was used to generate device code.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Milestone 1261

Supporting the latest hardware and compiler versions is important to leverage improvements in the software environment and new HPC platforms. We will provide certified support for the latest releases of vendor compilers from Intel, AMD, IBM, NVIDIA, ARM and Cray as well as of open source compilers GCC and Clang.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Using MLIR Framework for Codesign of ML Architectures Algorithms and Simulation Tools

MLIR (Multi-Level Intermediate Representation), is an extensible compiler framework that supports high-level data structures and operation constructs. These higher-level code representations are particularly applicable to the artificial intelligence and machine learning (AI/ML) domain, allowing developers to more easily support upcoming heterogeneous AI/ML accelerators and develop flexible domain specific compilers/frameworks with higher-level intermediate representations (IRs) and advanced compiler optimizations. The result of using MLIR within the LLVM compiler framework is expected to yield significant improvement in the quality of generated machine code, which in turn will result in improved performance and hardware efficiency

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Unified Language Frontend for Physic-Informed AI/ML

Artificial intelligence and machine learning (AI/ML) are becoming important tools for scientific modeling and simulation as in several other fields such as image analysis and natural language processing. ML techniques can leverage the computing power available in modern systems and reduce the human effort needed to configure experiments, interpret and visualize results, draw conclusions from huge quantities of raw data, and build surrogates for physics based models. Domain scientists in fields like fluid dynamics, microelectronics and chemistry can automate many of their most difficult and repetitive tasks or improve the design times by use of the faster ML-surrogates. However, modern ML and traditional scientific highperformance computing (HPC) tend to use completely different software ecosystems. While ML frameworks like PyTorch and TensorFlow provide Python APIs, most HPC applications and libraries are written in C++. Direct interoperability between the two languages is possible but is tedious and error-prone. In this work, we show that a compiler-based approach can bridge the gap between ML frameworks and scientific software with less developer effort and better efficiency. We use the MLIR (multi-level intermediate representation) ecosystem to compile a pre-trained convolutional neural network (CNN) in PyTorch to freestanding C++ source code in the Kokkos programming model. Kokkos is a programming model widely used in HPC to write portable, shared-memory parallel code that can natively target a variety of CPU and GPU architectures. Our compiler-generated source code can be directly integrated into any Kokkosbased application with no dependencies on Python or cross-language interfaces.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Oak Ridge National Laboratory Modernizing the Kokkos Build System: Using CMake to Encapsulate the Complexity of Build Instructions for Performance Portable Libraries

Kokkos, a C++ library focused on performance portability, requires a build system that can work with a variety of compilers and hardware. Ideally, users need only select the compiler and architecture and should not have to know or specify how programs using Kokkos are built. CMake can be used to create a flexible, robust build system and automatically configures compilers and settings based on the user’s inputs. Nevertheless, Kokkos’ requirements as a performance portability library for the build system exceed CMake’s current capabilities. This report describes the requirements, solutions, and testing of various implementations to create a CMake-based build system suitable for Kokkos. It compares the strengths and shortcomings of the approaches and evaluates the implementations with respect to the requirements. Because no solution was found to meet all of the requirements, the Kokkos team engaged with the CMake development team to discuss and plan a path toward support for performance-portable build systems in CMake in the future.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Thermal Tolerance Metrics for Freshwater Fish, CONUS, Version 1

This dataset is a compilation of 13 thermal response metrics for 834 freshwater fish species across the conterminous United States (CONUS). The data were extracted from six published sources, many of which are compilations of data from other sources. The data were harmonized for comparison, and additional variables were added to summarize the metrics. The dataset is presented as a spreadsheet containing 17 sheets. The first sheet (datasets) describes the data sources. Other sheets describe the source and compilation variables in detail.

13 HYDRO ENERGY↗
DOE OSTI2018

Relating soil gas to weathering using rock and regolith geochemistry

Weathering-induced fracturing (WIF) has been posited to be a mechanism that develops secondary porosity when mineral reaction fronts separate over depth intervals in regolith, and, in particular, when oxidation (which can promote porosity development through volume expansion) occurs deeper than dissolution (which grows porosity through material removal). If this is true, then the protolith’s capacity to reduce O2 (for example, the Fe(II) content) and O2 availability should affect WIF. This study explores the hypothesis that if the ratio of pO2 to pCO2, in soil water, R’(aq), is greater than the ratio of the capacity of the protolith to consume O2 and CO2, R0, then WIF is more likely to occur, and regolith will become thicker. We evaluated this hypothesis by measuring the bulk geochemistry of regolith and rock and monitoring soil gas at three sites, encompassing a wide range of FeO concentrations and regolith thickness: a Pennsylvania (PA) diabase (10.15%; 3.8 m), a Virginia (VA) diabase (10.49%; 1.4 m), and a VA granite (1.45%; 20 m). We inferred soil water O2 concentrations from calculated equilibrium with the measured soil gas pO2. We observed WIF in the VA granite and PA diabase where R’(aq) > R0, while at the site that lacked WIF – VA diabase – the R’(aq) < R0 particularly during the wet season. In the VA diabase, the presence of swelling clays (smectite) limits the ability of the oxidant (O2) to diffuse deeper into the weathering profile during the wet season and microbially accelerated iron oxidation rapidly consumes O2, limiting O2 availability for WIF. Smectite has little to no observable effect on O2 consumption in the PA diabase because the PA diabase is more fractured. A compilation of dissolved soil gas oxidation ratios, the stoichiometric ratio of O2 consumed to CO2 produced, shows that for unsaturated conditions, the mean is -1.45 ± 0.88, which is consistent with aerobic root and microbial respiration and the oxidation of organic matter. For near-saturated conditions, the mean oxidation ratio of the compilation is -3.46 ± 1.79, which is consistent with Fe redox and microbial metabolism under reducing conditions. The consistency between the VA and PA data presented here and the compilation suggests that soil-water surplus drives coupled Fe-redox reactions that may act as a negative feedback, limiting O2 supply and WIF under wetter soil moisture conditions. We defined Rz, the ratio of O2 consumption to CO2 consumption during weathering for each depth interval, z. For all profiles, R’(aq) > Rz near the surface but R’(aq) approaches Rz in the saprolite. We suggest that R’(aq) > Rz in the soil reflects consumption of O2 and production of CO2 due to biotic processes whereas R’(aq) approaching Rz suggests that low fluxes at depth are at least partly dictated by rock and regolith composition, notably tortuosity of pores. In the VA diabase, we observed R’(aq) < Rz occasionally during the wet season in the lowermost soil and saprolite. Thus, at times the O2 availability may be less than the O2 consumption at that depth, consistent with Fe(II) loss and a lack of WIF. Mass-balance calculations show Fe loss in the VA diabase. The influence of rock composition on aqueous O2/CO2 concentrations in saprolite is consistent with the hypothesis that the protolith’s capacity to consume O2 and CO2 has some effect on oxidation and acid consumption deep in the weathering profile.

54 ENVIRONMENTAL SCIENCES↗