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University of Nebraska - Lincoln

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Articles 331 - 360 of 455

Full-Text Articles in Biological Engineering

Effect Of Screw Configuration And Speed On Rtd And Expansion Of Rice Extrudate, Siew-Yoong Lee, Kathryn L. Mccarthy May 1996

Effect Of Screw Configuration And Speed On Rtd And Expansion Of Rice Extrudate, Siew-Yoong Lee, Kathryn L. Mccarthy

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The influence of screw configuration and screw speed on the residence time distribution and product expansion was determined for rice meal processed in a corotating twin screw extruder. Screw speed had strong effect on the E(t)- and F(t)-diagrams, with the mean residence time varying inversely with screw speed from 206 s to 256 s. the F-diagram was modeled by the combination of perfect mixing and plug flow. the P estimates, which express the fraction of material in plug flow, varied inversely with screw speed from 0.41 to 0.55 for the operating conditions in this study. Both screw configuration and screw …

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Grazing And Haying Effects On Runoff And Erosion From A Former Conservation Reserve Program Site, John E. Gilley, B. D. Patton, P. E. Nyren, J. R. Simanton Jan 1996

Grazing And Haying Effects On Runoff And Erosion From A Former Conservation Reserve Program Site, John E. Gilley, B. D. Patton, P. E. Nyren, J. R. Simanton

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Grazing and haying effects on runoff and erosion from a former Conservation Reserve Program (CRP) site near Streeter, North Dakota, were determined. Treatments included undisturbed CRP, twice-over rotational grazing, season-long grazing, haying, and burning. Runoff and erosion were measured from simulated rainfall which was applied to 3.7 x 10.7 m (12.0 X 35.1 ft) plots. Following an initial stabilization period, no significant difference in runoff or erosion was found between the season-long grazing and burned treatments. Use of the CRP site for grazing or haying resulted in a significant increase in runoff compared to leaving the area in an undisturbed …

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Frequency Domain Image Analysis For Detecting Stress Cracks In Corn Kernels, Y. J. Han, Y. Feng, Curtis L. Weller Jan 1996

Frequency Domain Image Analysis For Detecting Stress Cracks In Corn Kernels, Y. J. Han, Y. Feng, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A corn kernel classification procedure was developed in the frequency domain using a two-dimensional Fourier Transform for inspection of stress cracks. Investigations were also conducted to define suitable conditions and optimum image resolution for viewing stress cracks in corn kernels using a computer vision system. A pre-processing procedure included contrast enhancement, edge enhancement, and kernel edge elimination to improve stress crack recognition. A Fast Fourier Transform algorithm was applied to the pre-processed images, and the transformation results were condensed into 33 feature signatures representing position or orientation invariant morphological features. A multivariate discriminant analysis and multiple regression analysis were used …

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Heat Curing Of Soy Protein Films, A. Gennadios, V. M. Ghorpade, Curtis L. Weller, M. A. Hanna Jan 1996

Heat Curing Of Soy Protein Films, A. Gennadios, V. M. Ghorpade, Curtis L. Weller, M. A. Hanna

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Modification of soy protein film properties by heat-curing was studied. Glycerin-plasticized films were cast from alkaline aqueous solutions of soy protein isolate. Films were heated at 80 or 95°C for 2, 6, 14, or 24 h. Tensile strength (TS), elongation at break (E), moisture content (MC), water solubility (WS), water vapor permeability (WVP), and color of heated and control films were measured. Heated films had increased TS and +b (yellowness) Hunter color values and reduced E, MC, WS, and WVP values. These effects were enhanced as heating time and temperature increased.

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Soy Protein Isolate/Poly(Ethylene Oxide) Films, V. M. Ghorpade, A. Gennadios, M. A. Hanna, Curtis L. Weller Jan 1995

Soy Protein Isolate/Poly(Ethylene Oxide) Films, V. M. Ghorpade, A. Gennadios, M. A. Hanna, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Films were prepared by casting and drying alkaline aqueous film-forming solutions of soy protein isolate (SPI). Four additional types of films were made by combining SPI with poly(ethylene oxide) (PEO) in SPI to PEO ratios of 19:1, 9:1, 4:1, and 1.5:1 (w/w). Glycerin was added to all film-forming solutions as a plasticizer at 60% of total solid weight. Addition of PEO decreased film tensile strength (TS) and increased elongation at break (E). TS values ranged from 1.4 to 3.9 MPa and E values ranged from 83 to 152%. Water vapor permeability of the films ranged from 3.0 x 10-9 …

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Thermomechanical Behavior Of Wheat Gluten Films: Effect Of Sucrose, Glycerin, And Sorbitol, George Cherian, Aristippos Gennadios, Curtis L. Weller, Pavinee Chinachoti Jan 1995

Thermomechanical Behavior Of Wheat Gluten Films: Effect Of Sucrose, Glycerin, And Sorbitol, George Cherian, Aristippos Gennadios, Curtis L. Weller, Pavinee Chinachoti

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Glass transition temperature (Tg) and mechanical and water vapor barrier properties of wheat gluten films containing glycerin, sucrose, glycerin-sucrose, and glycerin-sorbitol were studied. Glycerin and sucrose were immiscible; the wheat gluten film containing both solutes showed two separate thermal transitions (-58°C and -5°C, respectively). The low temperature (low-T) transition (-58°C) was due to a glycerin-rich region. The low-T tan δ peak height influenced the tensile strength and elongation linearly and the water vapor permeability (WVP) curvilinearly. However, the Tg failed to change with solute composition and exhibited low correlation with barrier and mechanical …

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Darcy-Weisbach Roughness Coefficients For Surfaces With Residue And Gravel Cover, John E. Gilley, Eugene R. Kottwitz Jan 1995

Darcy-Weisbach Roughness Coefficients For Surfaces With Residue And Gravel Cover, John E. Gilley, Eugene R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Several types of hydraulic resistance factors may be present on upland agricultural areas. It is not known whether roughness contributions from individual elements are additive or if interactions between resistance factors may occur. In this study, Darcy-Weisbach roughness coefficients were measured on surfaces containing corn-soybeans, sorghum-cotton, and sunflower-wheat residue in addition to gravel cover. Varying rates of flow were introduced into a flume in which residue and gravel materials were securely attached. Roughness coefficients were calculated from measurements of discharge rate and flow velocity for Reynolds number values varying from approximately 1,200 to 13,000. The laboratory data were then used …

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Auger Design For Uniform Unloading Of Granular Material: I. Rectangular Cross-Section Containers, David D. Jones, Michael F. Kocher Jan 1995

Auger Design For Uniform Unloading Of Granular Material: I. Rectangular Cross-Section Containers, David D. Jones, Michael F. Kocher

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Design equations were developed for two auger configurations that for practical purposes generate uniform vertical flow of granular material through containers or boxes having a rectangular cross-section. Both configurations have uniform outside diameters so the simple geometry of the conventional U-trough housings could be used with these augers. One configuration had a uniform pitch for the auger flighting and decreasing inside diameter. The other had a uniform inside diameter and a decreasing pitch of the flighting with distance from the outlet end of the auger. Both configurations dramatically improved the uniformity of flow over the conventional auger. However, confidence intervals …

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Auger Design For Uniform Unloading Of Granular Material: Ii. Cylindrical Containers, Michael F. Kocher, David D. Jones Jan 1995

Auger Design For Uniform Unloading Of Granular Material: Ii. Cylindrical Containers, Michael F. Kocher, David D. Jones

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The analysis presented can be used to determine the design equations for augers that produce uniform vertical flow of granular material through containers with cylindrical cross-sections. The augers so designed have a constant outside diameter and a variable root or shaft diameter. Installed in cylindrical grain bins they could be used to convert a batch-in-bin dryer to a continuous flow dryer. The analysis is an extension of the work of Jones and Kocher (1995) who designed and tested such an auger for containers of rectangular cross-section, and determined flow to be uniform for practical purposes. The analysis follows the same …

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Corn Residue Cover On The Soil Surface After Planting For Various Tillage And Planting Systems, David P. Shelton, Elbert C. Dickey, Stephen D. Kachman, K.T. Fairbanks Jan 1995

Corn Residue Cover On The Soil Surface After Planting For Various Tillage And Planting Systems, David P. Shelton, Elbert C. Dickey, Stephen D. Kachman, K.T. Fairbanks

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Crop residue left on the soil surface after planting is one of the most cost-effective soil erosion control practices, and is a primary component of the majority of conservation plan that have been developed to comply with the conservation provisions of the 1985 Food Security Act. However, from contacts in Extension meetings and demonstrations, it became apparent that formers frequently misunderstood certain aspects of crop residue management, particularly the effects that tillage and other operations had on residue cover. To help address some of these questions, we measured percent residue cover remaining on the soil surface after planting for 69 …

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Random Roughness Assessment By The Pin And Chain Method, John E. Gilley, E. R. Kottwitz Jan 1995

Random Roughness Assessment By The Pin And Chain Method, John E. Gilley, E. R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Surface microrelief is frequently characterized using random roughness factors (RRF) defined by Allmaras et al. (1966). Random roughness factors are usually measured using a pin roughness meter or laser. Saleh (1993) recently proposed the chain method as a relatively simple, fast, and inexpensive technique for characterizing surface microrelief. The chain method is based on the principle that as a chain of given length is placed across a surface, the horizontal distance covered by the chain will decrease as surface roughness increases. Reductions in chain length caused by surface roughness are described as Saleh roughness factors (SRF).
In this study, RRF …

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Maximum Surface Storage Provided By Crop Residue, John E. Gilley, Eugene R. Kottwitz Jun 1994

Maximum Surface Storage Provided By Crop Residue, John E. Gilley, Eugene R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Small ponds created by crop residue serve to store water on upland areas. The present study is conducted to identify the maximum surface storage provided by crop residue. Equations for estimating surface storage are derived assuming that residue elements were oriented end to end, at uniform intervals, in a direction perpendicular to flow. Separate equations are developed for conditions where average slope was greater than or equal to residue cover, or less than residue cover. Both equations relate average surface-storage depth to residue cover, residue diameter, and average slope. Data to test the reliability of the equations are obtained in …

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Hydraulic Conditions Required To Move Unanchored Residue Materials, John E. Gilley, E. R. Kottwitz, G. A. Wieman Jun 1994

Hydraulic Conditions Required To Move Unanchored Residue Materials, John E. Gilley, E. R. Kottwitz, G. A. Wieman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Hydraulic conditions required to initiate movement of unanchored residue materials are identified in the present study. Selected amounts of corn, cotton, pine needles, sorghum, soybean, sunflower, and wheat residue are placed in a flume on a sand surface, and flow is then introduced at the top of the flume in progressive increments. The discharge rate and flow velocity necessary to cause residue movement are determined. The ratio of critical flow depth to residue diameter, critical Reynolds number, critical shear stress, dimensionless shear stress, and boundary Reynolds number are calculated from hydraulic measurements. Regression equations are developed to relate dimensionless shear …

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Darcy-Weisbach Roughness Coefficients For Selected Crops, John E. Gilley, E. R. Kottwitz Jan 1994

Darcy-Weisbach Roughness Coefficients For Selected Crops, John E. Gilley, E. R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Total hydraulic resistance on an upland agricultural site may be influenced by several factors including standing vegetation. In this laboratory study, Darcy-Weisbach roughness coefficients were measured for corn, cotton, sorghum, soybeans, sunflower, and wheat vegetation. Experimental variables used in this investigation in addition to crop type included plant population, row spacing, row orientation, and flow rate. For some of the experimental tests, a single row of vegetation was oriented within a flume parallel to the principal flow direction. For the remainder of the tests, rows of vegetation were placed perpendicular to the flow using row spacings and plant populations recommended …

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Water Vapor Permeability And Mechanical Properties Of Grain Protein-Based Films As Effected By Mixtures Of Polyethylene Glycol Amd Glycerin Plasticizers, H. J. Park, J. M. Bunn, Curtis L. Weller, P. J. Vergano, R. F. Testin Jan 1994

Water Vapor Permeability And Mechanical Properties Of Grain Protein-Based Films As Effected By Mixtures Of Polyethylene Glycol Amd Glycerin Plasticizers, H. J. Park, J. M. Bunn, Curtis L. Weller, P. J. Vergano, R. F. Testin

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Grain protein-based films containing mixtures of glycerin and polyethylene glycol (PEG) as plasticizers were prepared and evaluated for water vapor permeability (WVP), tensile strength (TS), and elongation (E). Changes in mechanical properties during storage were also studied. The PEG produced opposite trends in E of wheat gluten and corn-zein films. The TS of wheat gluten films increased and E of the films decreased as the ratio of glycerin/PEG decreased. Corn-zein films containing only glycerin were very brittle (E of 4%), and E of the films improved to 94% when the ratio of mL PEG/g protein was 0.39. The WVP of …

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Long Term Tillage Effects On Grain Yield And Soil Properties In A Soybean/Grain Sorghum Rotation, Elbert C. Dickey, Paul J. Jasa, Robert Grisso Jan 1994

Long Term Tillage Effects On Grain Yield And Soil Properties In A Soybean/Grain Sorghum Rotation, Elbert C. Dickey, Paul J. Jasa, Robert Grisso

Department of Agricultural and Biological Systems Engineering: Faculty Publications

In Nebraska, early adopters of conservation tillage, especially those using no-till planting, had some concerns regarding planter performance, early season weed control, and possible yield reductions. Selected tillage and planting systems were used long term to evaluate effects on soybean [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] yield, soil properties, and residue cover in a non-irrigated rotation. The six tillage and planting systems selected for evaluation were: no-till, no-till with row-crop cultivation, disk, double disk, chisel, and plow. In 1981, two sets of field plots were established near Lincoln, NE, on a Sharpsburg silty …

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Tillage And Planting System, Stalk Chopper, And Knife Applicator Influences On Corn Residue Cover, David P. Shelton, Stephen D. Kachman, Elbert C. Dickey, K.T. Fairbanks, Paul J. Jasa Jan 1994

Tillage And Planting System, Stalk Chopper, And Knife Applicator Influences On Corn Residue Cover, David P. Shelton, Stephen D. Kachman, Elbert C. Dickey, K.T. Fairbanks, Paul J. Jasa

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Percent corn (Zea mays L.) residue cover remaining on the soil surface after planting was measured for 11 tillage and planting systems that included combinations of the use, and timing, of a stalk chopper and/or a knife-type fertilizer applicator. Tillage, as well as use of a stalk chopper or knife applicator, significantly reduced residue cover. Only 27 of the 69 stalk chopper/knife applicator/tillage and planting system treatment combinations that were evaluated could be classified as conservation tillage by having at least 30% residue cover remaining after planting.

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Moisture Adsorption By Grain Protein Films, A. Gennadios, Curtis L. Weller Jan 1994

Moisture Adsorption By Grain Protein Films, A. Gennadios, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Grain protein films plasticized with glycerol were prepared from corn zein (CZ), wheat gluten (WG), and a 2.3:1 mixture of wheat gluten and soy protein isolate (WG/SPI). Moisture adsorption curves of the three types of protein films at 25° C and within an approximate water activity range of 0.11 to 0.84 were obtained using a static gravimetric method. The Smith, Oswin, Halsey, and Guggenheim-Anderson-de Boer (GAB) models were applied to collected data. For all protein films, the GAB model showed the best fit over the entire studied water activity range yielding mean deviation modulus values (P) of 4.69, 3.44, and …

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Closure To "Darcy-Weisbach Roughness Coefficients For Gravel And Cobble Surface", John E. Gilley, Eugene R. Kottwitz, Gary A. Wieman Oct 1993

Closure To "Darcy-Weisbach Roughness Coefficients For Gravel And Cobble Surface", John E. Gilley, Eugene R. Kottwitz, Gary A. Wieman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The writers appreciate the interest expressed by the discussers in this manuscript, and are pleased to have the opportunity to further discuss this material. The discussion states that the writers have generally examined a condition already investigated in other previous studies. Reynolds number values and roughness element size for the articles referenced by the discussers are shown in Table 5. Since flow rate and Reynolds number values were not given by Ferro and Giordano (1991), data from this study are not included in Table 5.
It can be seen from Table 5 that the roughness element sizes examined by Bathurst …

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Simulated Thermal Performance Of A Solar Heated Floor, Michael F. Kocher, James A. Deshazer, Gerald R. Bodman Mar 1993

Simulated Thermal Performance Of A Solar Heated Floor, Michael F. Kocher, James A. Deshazer, Gerald R. Bodman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A low cost, simple solar heating system consisting of an active collector with an In-Floor Heat Distribution and Storage (IFHDS) system was developed in response to the energy crisis of the 1970s. A two-dimensional finite difference model was developed and used to simulate the performance of IFHDS system cross-sections. Simulation runs were conducted with a steady-periodic model for the temperature of the solar-heated air in the IFHDS system cross-section. The steady periodic simulation results indicated IFHDS system energy efficiency increases with decreasing air temperature in the room above the IFHDS system, peak temperature of the solar-heated air in the IFHDS …

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Critical Shear Stress And Critical Flow Rates For Initiation Of Rilling, John E. Gilley, W. J. Elliot, J. M. Laflen, J. R. Simanton Feb 1993

Critical Shear Stress And Critical Flow Rates For Initiation Of Rilling, John E. Gilley, W. J. Elliot, J. M. Laflen, J. R. Simanton

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This study was conducted to identify critical shear stress and critical flow rates required to initiate rilling on selected sites. The data used in this investigation were collected from soils located throughout the USA where crop residues had been removed, and moldboard plowing and disking had occurred. Runoff and soil loss measurements were made on sites where simulated rainfall was applied to preformed rills. Multiple regression analyses were used to relate critical shear stress values and critical flow rates to selected soil properties. The soil-based regression equations were found to provide reliable estimates. Information identified in this study will improve …

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Relative Humidity And Temperature Effects On Tensile Strength Of Edible Protein And Cellulose Ether Films, A. Gennadios, H. J. Park, Curtis L. Weller Jan 1993

Relative Humidity And Temperature Effects On Tensile Strength Of Edible Protein And Cellulose Ether Films, A. Gennadios, H. J. Park, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The effect of relative humidity and temperature on tensile strength of two types of protein-based [corn zein (CZ) and wheat gluten (WG)] and two types of cellulosic [methylcellulose (MC) and hydroxypropyl cellulose (HPC)] hydrophilic edible films was investigated.

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Property Modification Of Edible Wheat, Gluten-Based Films, A. Gennadios, Curtis L. Weller, R. F. Testin Jan 1993

Property Modification Of Edible Wheat, Gluten-Based Films, A. Gennadios, Curtis L. Weller, R. F. Testin

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Procedures were developed to produce edible wheat, gluten-based films. A film was produced as a standard. Five additional films were then produced by modifying the initial film-forming solution. Modifications included changing the plasticizer, partially substituting wheat gluten with soy protein isolate and corn zein, and incorporating two acetylated monoglyceride products. All films were characterized by measuring selected mechanical properties, and permeabilities to water vapor and to oxygen. Comparison of the films, in terms of their measured properties, indicates ways to improve the overall performance of the standard film as a potential packaging material. A main limitation of all of the …

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Drying Rate Constants For Yellow Dent Corn As Affected By Fatty Acid Ester Treatments, Curtis L. Weller, J. M. Bunn Jan 1993

Drying Rate Constants For Yellow Dent Corn As Affected By Fatty Acid Ester Treatments, Curtis L. Weller, J. M. Bunn

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Ethyl oleate and ethyl stearate solutions at various concentrations were used to treat corn samples prior to drying.

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Modification Of Physical And Barrier Properties Of Edible Wheat Gluten-Based Films, Aristippos Gennadios, Curtis L. Weller, Robert F. Testin Jan 1993

Modification Of Physical And Barrier Properties Of Edible Wheat Gluten-Based Films, Aristippos Gennadios, Curtis L. Weller, Robert F. Testin

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Edible films were produced from wheat gluten-based film-forming solutions. One film was produced as a control. Other types came from subjecting control films to three different soaking treatments. Three additional films were also produced by modifying the control film-forming solution. For all films, selected physical properties and permeability to water vapor and oxygen were measured. Comparisons indicated possible ways to improve the control film. All films were good oxygen barriers but limited water vapor barriers. Films containing hydrolyzed keratin had lower oxygen permeability (83%) and lower water vapor permeability (23%). Films containing mineral oil had lower water vapor permeability (25%). …

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Chemical Tracing Techniques For Evaluating Rill Hydraulics, John E. Gilley, Eugene R. Kottwitz Jan 1993

Chemical Tracing Techniques For Evaluating Rill Hydraulics, John E. Gilley, Eugene R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Development of water erοsiοn and surface water quality control practices requires information concerning the hydraulic characteristics of upland areas. The relatively small flow rates normally found within rills make measurement of hydraulic parameters difficult. Chemical tracing procedures, originally developed for stream and river systems, have been successfully used to measure rill flow properties. A chemical tracer of known concentration is added to the rill and by knowing the degree of dilutiοn at a downstream sampling point, flow rate can be calculated. Rill flow velocity can be measured by determining the time required for a slug of tracer material to travel …

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Sediment Delivery On Rill And Interrill Areas, John E. Gilley, D. C. Kincaid, W. J. Elliot, J. M. Laflen Dec 1992

Sediment Delivery On Rill And Interrill Areas, John E. Gilley, D. C. Kincaid, W. J. Elliot, J. M. Laflen

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Equations which relate sediment delivery to a power function of flow rate and slope gradient were calculated in this study. The data used to parameterize the calculations were obtained from sites where crop residues had been removed. and moldboard plowing and disking had occurred. Measurements of sediment delivery resulting from simulated rainfall were obtained from preformed rills and interrill areas. The equations provided reliable sediment delivery estimates for selected soils located throughout the United States. To use the sediment delivery equations, soil-related parameter values must be identified. Multiple regression analyses were performed to relate parameter values used in the equations …

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Beginning Of Motion For Selected Unanchored Residue Materials, John E. Gilley, Eugene R. Kottwitz Aug 1992

Beginning Of Motion For Selected Unanchored Residue Materials, John E. Gilley, Eugene R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Conservation tillage systems help to maintain residue materials from the previous crop on the soil surface. The potential for serious erosion may exist if crop residues are removed by overland flow. This study is conducted to identify the hydraulic conditions required to initiate residue movement by overland flow. Corn, cotton, peanut, pine needles, sorghum, sunflower, and wheat residue are placed in a flume on smooth and sand surfaces, and flow is then introduced in progressive increments. The discharge rate and flow velocity required to initiate residue movement are identified. Hydraulic measurements are used to calculate the ratio of critical flow …

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Darcy-Weisbach Roughness Coefficients For Gravel And Cobble Surfaces, John E. Gilley, Eugene R. Kottwitz, Gary A. Wieman Feb 1992

Darcy-Weisbach Roughness Coefficients For Gravel And Cobble Surfaces, John E. Gilley, Eugene R. Kottwitz, Gary A. Wieman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A laboratory study is conducted to measure Darcy-Weisbach roughness coefficients for selected gravel and cobble materials. Varying rates of flow are introduced into a flume in which a given size class of gravel or cobble material is securely attached. Roughness coefficients are calculated from measurements of discharge rate and flow velocity. The laboratory data are used to develop regression equations for relating roughness coefficients to surface cover and Reynolds number. The regression relations, which are developed for values of the Reynolds number from approximately 500 to 16,000, are tested using hydraulic data collected on surfaces containing a distribution of size …

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Performance Of Chemigation Backflow Prevention Assemblies, H. M. Munir, Dean E. Eisenhauer, John E. Gilley Jan 1992

Performance Of Chemigation Backflow Prevention Assemblies, H. M. Munir, Dean E. Eisenhauer, John E. Gilley

Department of Agricultural and Biological Systems Engineering: Faculty Publications

When chemicals are applied using irrigation systems, there is potential for contamination of the water source by backflow if the irrigation system shuts off while unattended. This study was conducted to determine the operating and performance characteristics of new, i.e., unused, chemigation backflow prevention assemblies (CBPAs). Four manufacturer's models were tested in the laboratory. However, two of CBPAs have been modified since the testing was completed. In general, the CBPAs do not meet the standards established for municipal water suppliers and many industries. The backpressures required for the two current models to seal were 0.0 and 6.7 kPa (1.0 psi). …

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