The Cosmic-ray Neutron Probe Method for Estimating Field Scale Soil Water Content: Advances and Applications

The need for accurate, real-time, reliable, and multi-scale soil water content (SWC) monitoring is critical for a multitude of scientific disciplines trying to understand and predict the earth’s terrestrial energy, water, and nutrient cycles. One promising technique to help meet this demand is fixed and roving cosmic-ray neutron probes (CRNP). However, the relationship between observed low-energy neutrons and SWC is affected by local soil and vegetation calibration parameters. This effect may be accounted for by a calibrated equation based on local soil type and the amount of standing biomass. However, determining the calibration parameters for this equation is labor and time intensive, thus limiting the full potential of the roving CRNP in large surveys and long transects, or its use in novel environments. In this work, our objective is to develop and test the accuracy of using globally available datasets (clay weight percent, soil bulk density, and soil organic carbon) to support the operability of the CRNP. Here, we develop a 1 km product of soil lattice water over the CONtinental United States (CONUS) using a database of in-situ calibration samples and globally available soil taxonomy and soil texture data. We then test the accuracy of the global dataset in the CONUS using comparisons of 61 in-situ samples of clay percent (RMSE = 5.45 wt. %, R2 = 0.68), soil bulk density (RMSE = 0.173 g/cm3, R2 = 0.203), and soil organic carbon (RMSE = 1.47 wt. %, R2 = 0.175). In addition, we conduct an uncertainty analysis of the global soil calibration parameters using a Monte Carlo error propagation analysis (maximum RSME ~0.035 cm3/cm3 at a SWC = 0.40 cm3/cm3). Fast growing crops (i.e. maize and soybeans) contribute to the CRNP signal primarily through the water within their biomass and this signal must be minimized for soil moisture retrieval. This was done by using a vegetation index derived from MODIS imagery as a proxy for standing wet biomass (RMSE \u3c 1 kg/m2). Lastly, we make recommendations to the design and validation of future roving CRNP experiments. Advisor: Trenton E. Fran

The Cosmic-ray Neutron Probe Method for Estimating Field Scale Soil Water Content: Advances and Applications

The need for accurate, real-time, reliable, and multi-scale soil water content (SWC) monitoring is critical for a multitude of scientific disciplines trying to understand and predict the earth’s terrestrial energy, water, and nutrient cycles. One promising technique to help meet this demand is fixed and roving cosmic-ray neutron probes (CRNP). However, the relationship between observed low-energy neutrons and SWC is affected by local soil and vegetation calibration parameters. This effect may be accounted for by a calibrated equation based on local soil type and the amount of standing biomass. However, determining the calibration parameters for this equation is labor and time intensive, thus limiting the full potential of the roving CRNP in large surveys and long transects, or its use in novel environments. In this work, our objective is to develop and test the accuracy of using globally available datasets (clay weight percent, soil bulk density, and soil organic carbon) to support the operability of the CRNP. Here, we develop a 1 km product of soil lattice water over the CONtinental United States (CONUS) using a database of in-situ calibration samples and globally available soil taxonomy and soil texture data. We then test the accuracy of the global dataset in the CONUS using comparisons of 61 in-situ samples of clay percent (RMSE = 5.45 wt. %, R2 = 0.68), soil bulk density (RMSE = 0.173 g/cm3, R2 = 0.203), and soil organic carbon (RMSE = 1.47 wt. %, R2 = 0.175). In addition, we conduct an uncertainty analysis of the global soil calibration parameters using a Monte Carlo error propagation analysis (maximum RSME ~0.035 cm3/cm3 at a SWC = 0.40 cm3/cm3). Fast growing crops (i.e. maize and soybeans) contribute to the CRNP signal primarily through the water within their biomass and this signal must be minimized for soil moisture retrieval. This was done by using a vegetation index derived from MODIS imagery as a proxy for standing wet biomass (RMSE \u3c 1 kg/m2). Lastly, we make recommendations to the design and validation of future roving CRNP experiments. Advisor: Trenton E. Fran

Developments in impact damage modeling for laminated composite structures

Damage tolerance is the most critical technical issue for composite fuselage structures studied in the Advanced Technology Composite Aircraft Structures (ATCAS) program. The objective here is to understand both the impact damage resistance and residual strength of the laminated composite fuselage structure. An understanding of the different damage mechanisms which occur during an impact event will support the selection of materials and structural configurations used in different fuselage quadrants and guide the development of analysis tools for predicting the residual strength of impacted laminates. Prediction of the damage state along with the knowledge of post-impact response to applied loads will allow for engineered stacking sequencies and structural configurations; intelligent decisions on repair requirements will also result

Effects of intra- and inter-laminar resin content on the mechanical properties of toughened composite materials

Composite materials having multiphase toughened matrix systems and laminate architectures characterized by resin-rich interlaminar layers (RIL) have been the subject of much recent attention. Such materials are likely to find applications in thick compressively loaded structures such as the keel area of commercial aircraft fuselages. The effects of resin content and its interlaminar and intralaminar distribution on mechanical properties were investigated with test and analysis of two carbon-epoxy systems. The RIL was found to reduce the in situ strengthening effect for matrix cracking in laminates. Mode 2 fracture toughness was found to increase with increasing RIL thickness over the range investigated, and Mode 1 interlaminar toughness was negligibly affected. Compressive failure strains were found to increase with increasing resin content for specimens having no damage, holes, and impact damage. Analytical tools for predicting matrix cracking of off-axis plies and damage tolerance in compression after impact (CAI) were successfully applied to materials with RIL

Prospectus, October 21, 1971

GOOD ELECTION MARRED BY LIGHT TURN-OUT; Lieutenant Governor Simon Speaks To College Democrats of Illinois; Arc Triangle; Seed For Thought; Bull Sheet: Key Notes, S.W.A.M.P. Conducts Membership Drive, I.O.C. Special, Library Hours For Veterans Day Weekend, Gymnastics, Ski Club, Phi Beta Lambda, Draft Deferments For Freshman; Student Government In Action; News Briefshttps://spark.parkland.edu/prospectus_1971/1003/thumbnail.jp

Prospectus, October 2, 1970

GRADING SYSTEM HAS N\u27S AND I\u27S; New Policies Started For Parkland College; S.W.A.M.P. Fights Pollution, Apathy; Some Things To Come; Pollution-Sollution?: A Personal Challenge; Student Conduct Rules; Bull Page: News Shorts, New Teachers, Community Theatre 1970-1971 Season, Upcoming Movies, Charley Chan; Parkland College Golf Schedule 1970-71; Cheerleading Tryouts; Linksmen Open Fall Season; Intramurals Starthttps://spark.parkland.edu/prospectus_1970/1026/thumbnail.jp