Stephen J. Marley

Fuel properties and emissions of soybean oil esters as diesel fuel

The effects of using blends of methyl and isopropyl esters of soybean oil with No. 2 diesel fuel were studied at several steady-state operating conditions in a four-cylinder turbocharged diesel engine. Fuel blends that contained 20, 50, and 70% methyl soyate and 20 and 50% isopropyl soyate were tested. Fuel properties, such as cetane number, also were investigated. Both methyl and isopropyl esters provided significant reductions in particulate emissions compared with No. 2 diesel fuel. A blend of 50% methyl ester and 50% No. 2 diesel fuel provided a reduction of 37% in the carbon portion of the particulates and 25% in the total particulates. The 50% blend of isopropyl ester and 50% No. 2 diesel fuel gave a 55% reduction in carbon and a 28% reduction in total particulate emissions. Emissions of carbon monoxide and unburned hydrocarbons also were reduced significantly. Oxides of nitrogen increased by 12%.

Performance and exhaust emissions of a compression ignition engine operating on ester fuels at increased injection pressure and advanced timing

Abstract Effects of increased injection pressure and advanced injection timing on the performance and exhaust emission characteristics of a direct injection, naturally aspirated John Deere 4239D engine operating on methyl soyoil ester (IV (iodine value) = 125−135) and methyl tallow ester (IV = 47−53) were studied. The test engine was fully instrumented to provide all the required measurements for determination of the needed performance and exhaust emission variables. Four treatment combinations consisting of two levels of injection pressure (18.6 MPa and 24.1 MPa) and two levels of injection timing (19° before top-dead-centre (BTDC) and 14° BTDC) were employed. The physical and chemical properties of the test fuels were earlier determined in accordance to the ASTM and AOCS standards. Results indicated that the engine operating on ester fuels at the manufacturers injection pressure-timing setting (18.6 MPa and 14° BTDC) had lower carbon monoxide and unburned hydrocarbon carbon emissions and smoke levels, despite a slight increase in brake specific fuel consumption, as compared with when it was operating on No. 2 diesel fuel (control fuel). There were no significant differences in the engine brake specific fuel consumption and brake thermal efficiency between the ester fuels. However, between the two ester fuels, the saturated ester fuel (methyl tallow ester) showed slightly lower carbon monoxide and unburned hydrocarbons emissions, and higher smoke levels. The engine performance and exhaust emission characteristics of the engine operating on the ester fuels at advanced injection timing were better than when operating at increased injection pressure. Poor fuel combustion near the maximum operating power level was indicated with the engine operating on ester fuels at increased injection pressure. Complete fuel combustion was suppressed during high fuel flow probably due to the lack of oxygen within the spray envelope. Thus, fuels in some locations within the spray envelope that were too rich to burn escaped as unburned hydrocarbons, or burned incompletely causing high carbon monoxide and smoke levels in the exhaust emissions. Operating the engine at such conditions for extended periods could give rise to deposits problems in the combustion chamber. The engine performance and exhaust emission characteristics between the two ester fuels were almost similar at advanced injection timing and increased injection pressure.

Measurement of Field-Saturated Hydraulic Conductivity by Using Guelph and Velocity Permeameters

ABSTRACT Field experiments were conducted to evaluate the performance of two recently developed in situ techniques to measure saturated hydraulic conductivity (K). These two techniques are (1) the constant-head well permeameter method using the Guelph permeameter, and (2) the falling-head permeameter method using the velocity permeameter. K was measured on a silt loam soil at eight sites and for four different depths (150, 300, 450, 600 mm) at each site by using these two techniques. K determinations were also made in the laboratory by using a constant-head permeameter on undisturbed soil columns collected from all test sites and depths. Measurements of K for the selected test sites and conditions indicate that Guelph and velocity permeameters provided reasonably similar values. Both methods are simple to use and easily portable, and both produce results in a relatively short time (usually 15 min to 20 min for the velocity permeameter and 60 min to 90 min for the Guelph permeameter for a single measurement). Field-measured K values tended to be much lower than laboratory values.

AN EVALUATION OF SEED FURROW SMEARING

Seed furrow sidewall smearing describes compaction of soil in the seed zone that is caused, in some soil conditions, by the planter furrow opener and that may interfere with crop stand establishment. Soil smearing caused by planting with double disk furrow openers was investigated by measuring physical properties of soil in the seed furrow and by evaluating corn (Zea mays, L.) emergence and growth. Planter attachments for row preparation (no-coulter, single offset bubble coulter, and triple offset fluted coulter planter attachments) were evaluated for their influence on seed furrow sidewall smearing over a range of soil moisture contents. Planting tended to reduce soil bulk density in the 0 to 100 mm layer in the seed zone. In general, the soil was least dense when the triple-coulter attachment was used. Air permeability of soil samples taken from the seed furrow sidewall, before the furrow was closed, tended to decrease with increasing soil moisture. The triple-coulter treatment resulted in greater air permeability than did other coulter treatments. Soil penetration resistance below the seed and in the seed furrow sidewall was greatest for the single coulter and least for the triple coulter. We observed that more roots grew parallel to the soil surface with no-coulter and single-coulter treatments than with the triple-coulter treatment especially when soil property measurements indicated that more sidewall smearing had occurred. This research showed that row preparation by coulter planter attachments placed ahead of double-disk openers can reduce seed furrow sidewall smearing and may improve stand establishment of corn.

Background segmentation and dimensional measurement of corn germplasm

An automatic thresholding technique was developed to segment the background from the images of corn germplasm (ears of corn). The technique was a modification of Otsu’s algorithm using probability theory. Three different measures were used to evaluate the performance of the modified Otsu’s algorithm for background segmentation and subsequent dimensional measurement of corn germplasm. Modified Otsu’s algorithm was found to perform better than Otsu’s algorithm and was successful in automatic background segmentation of all 80 images of corn germplasm included in the study. This modified algorithm also eliminated the misclassification of exposed cob in the image as background which occurred with Otsu’s algorithm. Subsequent dimensional measurements based on the segmentation by the modified algorithm were also highly accurate.

Physical and chemical characterization of methyl soyoil and methyl tallow esters as CI engine fuels

Abstract Fourteen ASTM (American Society for Testing Materials) tests and four AOCS (American Oil Chemists Society) tests were employed to characterize the fuel properties of methyl soyoil ester and methyl ta;low ester. Soybean oil and animal tallow were considered in this study as the two are leading sources for alternative CI engine fuel. Comparisons and evaluations of the properties of the esters were made against the Phillips No. 2 control diesel fuel and the ASTM D975 requirement limits set for No. 2 diesel fuel. Results from this study indicated distinct differences in the chemical compositions and some of the physical properties between the ester fuels and No. 2 diesel fuel.

Verification of a Mathematical Model to Predict Tractor Tipping Behavior

Because of its available axle torque and geometric configuration, the usual farm tractor is not a particularly stable vehicle. In view of the increasing emphasis being placed on safety and comfort, a knowledge of the degree of stability to be expected from a tractor under various conditions of dynamic loading might be an aid in designing safer and more functional tractors. One method of attaining this knowledge would be the use of a mathematical model. The advantages offered by a mathematical model over prototype testing include greater speed, lower costs, and, more importantly, the ability to perform preliminary evaluation of proposed designs. Disciplines Agriculture | Bioresource and Agricultural Engineering Comments This article is from Transactions of the ASAE 13, no. 1 (1970): 67–72. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/abe_eng_pubs/223 Verification of a Mathematical Model to Predict Tractor Tipping Behavior J. A. Koch, W. F. Buchele, S. J. Marley Assoc. MEMBER ASAE MEMBER ASAE MEMBER ASAE B of its available axle torque and geometric configuration, the usual farm tractor is not a particularly stable vehicle. In view of the increasing emphasis being placed on safety and comfort, a knowledge of the degree of stability to be expected from a tractor under various conditions of dynamic loading might be an aid in designing safer and more functional tractors. One method of attaining this knowledge would be the use of a mathematical model. The advantages offered by a mathematical model over prototype testing include greater speed, lower costs, and, more importantly, the ability to perform preliminary evaluation of proposed designs. Throughout the past 45 years the mechanics of the unsprung wheel tractor has received considerable study. In the 1920s the quantitative approach to the problem began with the work of McKibben (8) .* Worthington (10) and Buchele (3) later analyzed the effects of pneumatic tires and soil variables, respectively, on the farm tractor. For reasons of simplicity these studies were limited to steady-state conditions. Raney and associates (9) established a mathematical model for simulating the vibratory behavior of a farm tractor, but because linear differential equations were used, the model is limited to only small amplitude vibrational studies. The work of Goering (4) in 1965 was the first to provide a mathematical model with the capability of completely predicting two-dimensional tractor mechanics. The model, involving nonlinear differential equations, is not restricted by assumptions of zero or constant accelerations or by small angular movement. However, before such a model can be usefully applied in the design of tractors, the accuracy of its predictions must be measured and the validity of the model verified. Paper No. 68-107 was presented at the Annual Meeting of the American Society of Agricultural Engineers at Logan, Utah, June 1968 on a program arranged by the Power and Machinery Division. Approved as Journal paper No. J-5945 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 1331. The authors—J. A. KOCH, W. F. BUCHELE, and S. J. MARLEY—are, respectively, design engineer, John Deere Waterloo Tractor Works, Waterloo, Iowa, and professor and associate professor of agricultural engineering, Iowa State University, Ames, Iowa. * Numbers in parentheses refer to the appended references. The objectives of the paper are to report the instrumentation and techniques that were used in verifying Goerings mathematical model and to present a comparison of actual backward tractor tipping behavior with response predicted by the model. The Mathematical Model The mathematical model was based on certain geometrical requirements, Newtons laws, and empirical information about several of the tractors components. Only a list of the assumptions made in developing the model and the final set of equations as programmed into the computer are given here. Those interested in a more complete discussion of the model should consult references (4) , (5) , and (7) . The following simplifying assumptions were made in the development of the model: 1. All motion of the tractor occurs in a plane normal to the supporting surface. 2 The laws of Newtonian mechanics are valid for measurements made on the tractor relative to the earth. 3. Only the tractor tires are deform able; the remaining parts of the tractor are rigid bodies. 4. The rear wheels have negligible mass but appreciable mass moments of inertia. 5. The front wheels have negligible mass and negligible mass moments of inertia. 6. The front wheels are grounddriven only. 7. Damping in the pneumatic tires is viscous damping. 8. All wheel ballast is solid, not liquid. 9. The tractor has an unlocked differential; i.e., torque in each drive wheel is equal. The set of the equations used in programming the computer follow. The terms of the equations are defined in Table 1 and principal parameters used in the model and free body diagrams of the major tractor components are shown in Figs. 1 and 2. The moment equation for a rear wheel was as follows: 8X) dt I2 fa = T Z21 (R28 R22) . [1] The above equation makes the additional assumptions that Z 2 1 = Z22, and X21 = 0. The moment equation for the chassis was expressed as: I Q dS = 2(X1 2 ft4Z12) R41dt + 2Tdt (WiXn) cos ( 0 + (WiZu) sin(© + 8x)dt 4W i * n ^ ( c o s e ) dt

Change in Soil Microtopography by Tillage with a Sweep

Information on effects of tillage sweep geometry and operation on soil conditions, including soil surface elevation, is needed for effective design, selection, and use of sweeps for row crop cultivation and ridge construction. The effects of sweep rake angle and of operation speed and depth on changes in soil microtopography were determined. Changes in microtopography due to observed soil aggregate movement were also found. A factorial arrangement of pairs of sweeps with three geometries operated at three speeds (5, 7, and 9 km/h) and at two depths (50 and 100 mm) were used to form ridges in a field experiment.

Simulated Tractor Chassis Suspension System

ABSTRACT THE development of a chassis suspension system for an agricultural tractor has been described to improve the operator ride comfort. Computer simulation tech-niques were used to formulate the tractor models and to compute the natural frequencies and frequency response of the models, as well as the RMS acceleration response, to evaluate the effect of the suspension system and cab position on operator ride comfort.

Spring-Damper Control of Lateral Cutting Angle for a Variable-Speed Moldboard Plow

ABSTRACT THE draft of a moldboard plow increases with forward speed. It has been demonstrated that this increase in draft can be controlled by reducing the lateral cutting angle as speed increases. This paper describes some spring-damper mechanisms used to control the lateral cutting angle of a mold-board plow bottom.