Browsing Scholarly Works, Biological Systems Engineering by Issue Date
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- Statistical distribution functions for bone strength of leghorn layersWilson, J. H. (American Society of Agricultural and Biological Engineers, 1992)Shear strength tests were conducted on tibia, humerus, and radius bones from white leghorn layers to establish the type of statistical distribution function that best fits poultry bone strength data. The results indicated that a three-parameter Weibull distribution best described the maximum shear force and stress of the tibia and a shifted log-normal distribution best described the maximum shear stress of the radius. None of the chosen distributions (normal, log-normal, Weibull, and gamma) fit the data for the maximum shear force of the radius or humerus. Because of the nonnormal nature of the distribution of poultry bone strength, nonparameter statistics should be used to analyze the data.
- Manure and wastewater management systems for open lot dairy operationsSweeten, J. M.; Wolfe, Mary Leigh (American Society of Agricultural and Biological Engineers, 1994)Dairy industry expansion using open lot designs has impacted water quality and groundwater usage in parts of Central Texas. Field research was conducted at commercial dairy farms in Erath County, Texas, to develop improved design criteria for storage, treatment, and land application systems for open lot dairies. Water use and wastewater from milking parlors were monitored along with runoff from open lots. Water use for milk sanitation and manure removal averaged 148 L per cow per day. Two-stage anaerobic lagoon systems achieved higher solids and nutrient removal efficiencies than a combination of settling basin and one-stage anaerobic lagoons. The two-stage anaerobic lagoon system with 81- to 118-day hydraulic retention time reduced concentrations of volatile solids (VS), chemical oxygen demand (COD), and total kjeldahl nitrogen (TKN) in dairy wastewater from milking parlors by 80 to 82%, 90 to 93% and 55 to 73%, respectively. Solids settling basins reduced VS, COD, and TKN concentrations in wastewater by 35 to 45%, 27 to 47%, and 14 to 24%, respectively. As compared to second-stage lagoon effluent, open lot runoff was higher in K, but similar in TKN and P concentrations and contained a greater proportion of fixed solids. Analysis showed that anaerobic lagoon effluent and open lot runoff were good sources of available plant nutrients.
- Economics of greenhouse heating with a mine air-assisted heat pumpMarsh, Lori S.; Singh, Sahdev (American Society of Agricultural and Biological Engineers, 1994)An analysis of the economics of greenhouse heating with a heat pump coupled with an inactive deep mine is presented. Several heat pump and conventional gas-fired heater combinations (hybrid systems) were evaluated using a computer model to perform thermal and economic analyses. A 10 x 30 m, double-polyethylene-covered greenhouse, located in Charleston, West Virginia, was assumed for this analysis. Heat pumps with sufficient capacity to maintain 21 degrees C inside the greenhouse for outside temperatures ranging from 0 to 20 degrees C (in 2 degrees degree increments) were modeled. For each heat pump capacity, it was assumed that the additional heat energy required to maintain the specified inside temperature (when outside temperature fell below the heat pump design temperature) was supplied by a natural gas-fired heater. Life-cycle cost analysis was employed to compare greenhouse heating alternatives. The hybrid system offers lower operating costs than a conventional system for any outside design temperature. However, when initial cost is also considered, the hybrid system has a higher life cycle cost for heat pump design temperatures in the range 0 to 18 degrees C and a coefficient of performance (COP) of 3. As the heat pump COP increases beyond 3, the hybrid system becomes economically feasible, showing a lower life cycle cost than a conventional natural gas-fired system.
- MIXFIT: A microcomputer-based routine for fitting heterogeneous probability distribution functions to dataCooke, R. A.; Mostaghimi, Saied (American Society of Agricultural and Biological Engineers, 1994)Some engineering data represent a mixture of data from two distinct populations or result from two or more concomitant phenomena. Homogeneous probability density functions are not always suitable for representing such data. This article describes the development of a procedure for fitting two types of heterogeneous density functions to mixed population data. The benefits derived from using these heterogeneous functions are evaluated with conventional goodness-of-fit tests.
- Laboratory measurements and modeling N mineralization potential in Virginia Coastal Plain agricultural, fallow, and forest soilsShukla, S.; Mostaghimi, Saied; Burger, James A. (American Society of Agricultural and Biological Engineers, 2000)A long-term aerobic incubation and leaching technique was used to measure N mineralization of surface and subsurface soils (sandy loam) from agricultural,forest, and fallow sites in a Virginia Coastal Plain watershed. N mineralization potential was measured to refine models used to describe this process in a watershed-scale nutrient export assessment. Potentially mineralizable N (N-0) and reaction rate constants (k) were estimated using a first-order model and a nonlinear regression procedure. Large variations in cumulative N mineralized, N-0, and k, were found for the surface soils from agricultural areas. Forest soils had much higher potentially mineralizable N than agricultural soils. For subsurface soils, the differences among land uses were less variable than those observed for the surface soils. The first order model (single-pool approach) was adequate for predicting N mineralization in surface soils from agricultural and fallow areas, but less suitable for forest surface soils. Consideration of a double exponential (two-pool approach) model did not improve the performance of N mineralization prediction for forested or agricultural soils. Large variations occurred in the field-predicted values of mineralized N due to temperature and moisture ranges commonly occurring throughout the season. Variability in the N mineralization potential of soils in the watershed suggests that individual k and N-0 should be derived for soils with similar properties to obtain better predictions of N mineralization and thus N movement to groundwater.
- Effects of forest harvesting best management practices on surface water quality in the Virginia coastal plainThompson, Theresa M.; Mostaghimi, Saied; Frazee, J. W.; McClellan, P. W.; Shaffer, R. M.; Aust, W. Michael (American Society of Agricultural and Biological Engineers, 2000)Three small watersheds located in Westmoreland County, Virginia, were monitored to evaluate the impact of forest clearcutting on surface water quality and to evaluate the effectiveness of forestry best management practices (BMPs) for minimizing hydrologic and water quality impacts associated with timber harvesting. One watershed (7.9 ha) was clearcut without implementation of BMPs, one watershed (8.5 ha) was clearcut with the implementation of BMPs and a third watershed (9.8 ha) was left undisturbed as a control Forest clearcutting without BMP implementation reduced storm runoff volume and did not significantly change peak flow rates. Following site preparation, both storm flow volumes and peak flow rates decreased significantly. For the watershed with BMP implementation, storm flow volume decreased significantly following harvest, while peakflow increased. Site preparation did not change storm flow volumes over post-harvest conditions, bur did significantly reduce storm peak flow rates. Disruptions in subsurface flow pathways during harvest or rapid growth of understory vegetation following harvest could have caused these hydrologic changes. Harvest and site preparation activities significantly increased the loss of sediment and nutrients during storm events, Storm event concentrations and loadings of sediment, nitrogen, and phosphorus increased significantly following forest clearcutting and site preparation of the No-BMP watershed. Both the BMP watershed and the Control watershed showed few changes in pollutant storm concentrations or loadings throughout the study. Results of this study indicate forest clearcutting and site preparation without BMPs can cause significant increases in sediment and nutrient concentrations and loadings in the Virginia Coastal Plain. However these impacts can be greatly reduced by implementing a system of BMPs on the watershed during harvesting activities.
- Relationships between drainage area, slope length, and slope gradient for riparian slopes in VirginiaInamdar, S. P.; Dillaha, Theo A. III (American Society of Agricultural and Biological Engineers, 2000)Surface runoff and interflow generated on riparian hillslopes concentrate along rills or topographic depressions as they move downslope. This runoff concentration is an important factor that determines the effectiveness of conservation practices such as vegetated filter ships and riparian buffers and needs to be accounted for while designing such practices. Currently, routinely available DEMs are not detailed enough to capture the runoff concentration that occurs at the hillslope scale. This article investigated the possibility of developing simple relationships that could be used to quantify specific or total contributing areas in terms of hillslope attributes such as slope length or gradient. Riparian hillslopes in the Ridge and Valley region of Virginia were surveyed. The bounds of the survey were defined by the size of dissected hollows and spurs for these hillslopes. Surface elevations were recorded at a resolution of 0.5 to 2 m. Catchment areas which were used as a surrogate for runoff concentration were determined using digital elevation models. Results from this study suggest that although some of the measures of runoff concentration could be expressed in terms of slope length and gradient, it is unlikely that complete probability distribution of catchment areas could be derived based simply on slope gradients and lengths.
- Plumbing systems of agricultural sprayersGrisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2001)The plumbing systems of agricultural sprayers are usually considered foolproof. Sprayer problems may occur if plumbing and/or modifications are improperly done or maintenance is ignored. Retrofitting, addition of electrical control systems, and replacement of pumps or nozzles require proper knowledge of the plumbing system and the implications of these changes to sprayer performance. Routine maintenance of the plumbing system is essential.
- Reliability of odor offensiveness quantification using the refined cloth swatch olfactometric techniqueGay, S. W.; Wheeler, E. F.; Kephart, K. B. (American Society of Agricultural and Biological Engineers, 2001)The cloth swatch olfactometric technique uses flannel swatches to absorb odors for presentation to a trained human sensory panel. This study examined the reliability of the refined cloth swatch technique used to facilitate the quantification of odor offensiveness of swine facility wastewater treated in subsurface-flow constructed wetlands. Reliability was based on the consistency of ratings assigned by panelists to odor sample replicate pairs. Panelists assigned odor replicate pairs ratings that differed by +/-0 or +/-1 with a 79% frequency, while differences of +/-0 and +/-1 between odor replicate pairs would occur with only a 44% frequency if ratings were randomly assigned. Although individual panelist error during individual trials varied among panelists, individual panelist error over all trials was found to be not significant (Z < 115, alpha=0.05). Statistical methods described here could be used to screen human sensory panelists during pre-trials. Overall, the swatch olfactometric technique used by human sensory panelists yielded highly consistent results and low overall error, indicating that odor offensiveness rating data obtained using the refined cloth swatch technique were reliable to use for various odor analyses.
- Ultrasonic water measurement in irrigation pipelines with disturbed flowJohnson, A. L.; Benham, Brian L.; Eisenhauer, D. E.; Hotchkiss, R. H. (American Society of Agricultural and Biological Engineers, 2001)Ultrasonicflow meter accuracy was investigated over a range of flow conditions (3 pipe materials, 2 pipe sizes, 4 Reynolds numbers, 7 flow-disturbing devices) commonly found in irrigation systems. Flow rate measurements were taken at five locations downstream from a flow disturbance. The measurement accuracy was within +/-5% of actual flow at a minimum of 10 pipe diameters downstream from the flow disturbances. Errors as high as 36.5% occurred when measurements were taken close to some flow disturbances. A multiplier was developed to correct for directional bias for devices that fell into the Group I category (single elbow, two elbows, check valve, and 50% open butterfly valve with vertical and horizontal orientation). Applying the multiplier at 4.5 pipe diameters and higher resulted in accuracies within +/-4% of actual flow. The regression analysis performed on Group I devices showed that the USFM performance was not significantly different for the three pipe materials, two pipe diameters, and four flow rates.
- Impact of agrichemical facility best management practices on runoff water qualityShukla, S.; Mostaghimi, Saied; Lovern, S. B.; McClellan, P. W. (American Society of Agricultural and Biological Engineers, 2001)Water quality effects of structural and managerial BMPs implemented at an agrichemical mixing and handling facility, located in an agricultural watershed in Virginia, were investigated in this study. The measured water quality parameters include two commonly used pesticides (atrazine and metolachlor), nitrogen (N), and phosphorus (P). BMPs implemented include: pesticide mixing and loading concrete pad with a sump and pump fitting; a variety of runoff diversion structures to divert the rooftop runoff away from the critical areas; structures to contain transport of chemicals to the drainage leaving the facility; and recycling of rinsate by applying it on the agricultural land. Concentration of pesticides and nutrients were measured at the facility outlet as well as the outlet of the main watershed in which the facility was located. Implementation of BMPs resulted in drastic reduction in mean concentrations of the two pesticides in the stream leaving the facility as well as in the main watershed stream. Maximum atrazine concentrations in the drainage leaving the facility reduced from 17,389 mug/l during the pre-BMP period (1986-1988) to 1,452 mug/l during the post-BMP period (1989-1996). The post-BMP mean concentrations of atrazine and metolachlor at the facility outlet were reduced by 94% (2690 mug/l to 166 mug/l) and 91% (4579 mug/l to 402 mug/l), respectively. The corresponding post-BMP reductions in concentration at the main watershed outlet were 52% and 78% for atrazine and metolachlor, respectively. Nonparametric trend tests results indicated statistically significant downward trend and reduced post-BMP concentrations of the two pesticides at the facility as well as the watershed outlets. Impact of BMPs on the nutrient concentrations were not clear due to large nutrient contributions from animal production activities in upland areas of the watershed Results from this study will provide needed impetus for implementation of BMPs at other agrichemical mixing and handling facilities in Virginia as well as other states to drastically reduce the transport of pesticides and nutrients to surface water bodies.
- Fine tuning a sprayer with ounce calibration methodGrisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2001)This extension publication discusses guidelines to quickly evaluate the performance of a sprayer. Sprayer calibration, nozzle discharge, spray pattern uniformity, speed checks, pump performance and plumbing arrangements are evaluated with minimal calculations.
- BMP impacts on sediment and nutrient yields from an agricultural watershed in the coastal plain regionInamdar, S. P.; Mostaghimi, Saied; McClellan, P. W.; Brannan, Kevin M. (American Society of Agricultural and Biological Engineers, 2001)The goal of the Nomini Creek watershed monitoring study was to quantify the effectiveness of BMPs at the watershed scale and to determine if the improvements in water quality could be sustained over a long-term period. Information on the long-term effectiveness of BMPs is critical since BMPs are being implemented under the state cost-share program to reduce nonpoint source pollution (NPS) to the Chesapeake Bay. The Nomini Creek project started in 1985 and was completed in 1997. A pre- versus post-BMP design was used. A combination of managerial and structural BMPs was implemented. Major BMPs implemented in the Nomini Creek watershed included no-tillage, filter strips, and nutrient management. The data collected at the 1463 ha Nomini Creek watershed consisted of land use, hydrologic, water quality, soils, and geographical information. The BMPs implemented at Nomini Creek reduced average annual loads and flow-weighted concentrations of nitrogen (N) by 26% and 41%, respectively. Average annual total-N loads discharged from the watershed were reduced from 9.57 kg/ha during the pre-BMP period to 7.05 kg/ha for the post-BMP period. Largest reductions were observed for dissolved ammonium-N, soluble organic-N, and particulate-N. In contrast, nitrate-N loads increased after BMP implementation. Increase in nitrate exports was likely due to ammonfication and nitrification, and subsequent leaching of particulate-N species that were conserved on the field. In comparison to N, reductions in phosphorus (P) loads and concentrations were not significant. BMP implementation resulted in a mere 4% reduction for total-P with a corresponding 24% reduction in flow-weighted concentration. The average annual total-P loads exported from the watershed were 1.31 and 1.26 kg/ha for the pre- and post-BMP periods, respectively. Reductions in total-P loads were due to decreases in particulate-P. Exports of ortho-P and dissolved organic-P increased after BMP implementation. It is likely that some of this post-BMP increase in dissolved P fractions was associated with dissolution and leaching of particulate-P, and higher rainfall-runoff activity in the watershed during the post-BMP period. In comparison to nutrients, there was no significant change in suspended solids discharged from the watershed. Overall, the findings of this study indicate that the BMPs were effective in reducing the losses of some forms of nutrients, such as ammonium-N and particulate-P, from the Nomini Creek watershed, but additional BMIs are necessary to achieve significant reductions in all forms of N and P.
- The influence of lactose hydrolysis on the strength and sensory characteristics of vanilla ice creamMatak, Kristen E.; Wilson, James H.; Duncan, Susan E.; Wilson, Edward J.; Hackney, Cameron Raj; Sumner, Susan S. (American Society of Agricultural and Biological Engineers, 2003)Lactose hydrolysis was investigated as a method of producing a more extrudable ice cream product. Ice cream mixes were treated with lactase from the microbial sources Kluyveromyces lactis and Aspergillus oryzae to produce 0% to 100% lactose hydrolysis. Compression measurements and yield stress tests of frozen ice cream were both affected by the temperature of the samples. As the temperature decreased, the work required to compress the ice cream 10 mm (firmness) and the torsional shear stress both increased. There was a linear relationship between the firmness of lactose-hydrolyzed ice cream (0%, 80%, and 100%) and temperature (r(2) = 0.98, 0.99, and 0.97, respectively). The treated samples were significantly softer that? the control, but not different from each other There was a significant difference (p < 0.05) in ice cream dippability between the control samples (0% hydrolyzed) and the treatment groups (80% and 100% hydrolyzed). The control group was consistently harder to dip. Hydrolysis of lactase in the ice cream mix produced a softer, more extrudable product.
- Low Dose Gamma Irradiation to Reduce Pathogenic Vibrios in Live OystersAndrews, L.; Jahncke, M.; Mallikarjunan, Kumar (2003)
- Cost-effective BMP placement: Optimization versus targetingVeith, Tamie L.; Wolfe, Mary Leigh; Heatwole, Conrad D. (American Society of Agricultural and Biological Engineers, 2004)Cost-effectiveness of nonpoint-source pollution reduction programs in an agricultural watershed depends on the selection and placement of control measures within the watershed. Locations for best management practices (BMPs) are commonly identified through targeting strategies that define locations for BMP implementation based on specific criteria uniformly applied across the watershed. The goal of this research was to determine if cost-effectiveness of BMP scenarios could be improved through optimization rather than targeting. The optimization procedure uses a genetic algorithm (GA) to search for the combination of site-specific practices that meets pollution reduction requirements, and then continues searching for the BMP combination that minimizes cost. Population size, replacement level, crossover, and mutation parameters for the GA were varied to determine the most efficient combination of values. A baseline scenario, a targeting strategy, and three optimization plans were applied to a 1014 ha agricultural watershed in Virginia. All three optimization plans identified BMP placement scenarios having lower cost than the targeting strategy solution for equivalent sediment reduction. The targeting strategy reduced average annual sediment loss compared to the baseline at a cost of $42 per kg sediment reduction/ha. The optimization plan with the same BMP choices achieved the same sediment reduction at a cost of $36 per kg/ha. Allocation of BMPs varied among optimization solutions, a possibility not available to the targeting strategy. In particular the optimization solutions placed BMPs on several stream-edge fields that did not receive BMPs in the targeting strategy.
- Cover crop/dairy manure management systems: Water quality and soil system impactsKern, James D.; Wolfe, Mary Leigh (American Society of Agricultural and Biological Engineers, 2005)A field study was conducted to determine impacts of corn silage production systems that included a rye cover crop and application of liquid dairy manure in the spring and fall on water quality and soil characteristics. Four management systems were each replicated four times: traditional, double-crop, roll-down, and undercut. Manure was applied below the soil surface during the undercutting process; otherwise, manure was surface applied. In the roll-down system, the rye crop was fattened with a heavy roller after manure application. Rainfall was simulated within 48 h of manure application to produce runoff events. Grab samples of runoff were collected and composited for analysis. Soil samples were collected prior to treatments in the fall and spring. The roll-down system had no significant effect on water quality (sediment, nutrients, bacteria) as compared to the traditional system. While the roll-down system may require an occasional tillage operation to prevent surface compaction, it is recommended in situations where reduction of residual herbicide applications is a primary concern. The undercut system displayed evidence of a compaction layer developing below the disturbed soil layer. The undercut system reduced loadings of all nutrients, but increased losses of total suspended solids, as compared with all other systems. Mean volume of runoff from the undercut system was less than half that from any other system. Overall, the undercut system is recommended over the other systems analyzed for preventing transport of manure constituents to surface water, but should be evaluated in a complete dairy system before it is implemented by producers.
- Sensitivity analysis of the Virginia phosphorus index management toolJesiek, Julie B.; Wolfe, Mary Leigh (American Society of Agricultural and Biological Engineers, 2005)The phosphorus index (P-Index) is a risk assessment and management tool to aid in reducing the risk to water quality due to movement of excess phosphorus (P) from fields. An allowable P application rate is specified based on the computed risk. This study focused on the Virginia P-Index. The objectives were to determine the factors to which the P-Index is most sensitive and to determine the factors to which the resulting P application rate recommendations are most sensitive. A differential analysis was used to calculate relative sensitivity for nine baseline scenarios: a low, medium, and high baseline within three different regions of Virginia. Impact of user variability in estimating factor values was evaluated using a probability distribution analysis. The P-Index was most sensitive in the low and medium baseline scenarios to P management factors, including annual application rate, method of fertilizer application, and source availability factor In high-risk baseline scenarios, the P-Index was most sensitive to transport factors (erosion, runoff, or leaching). User variability had a greater impact on the P-Index and on P application rate recommendations as P risk increased over each of the three regions. The closer afield's P-Index value is to a threshold between P recommendation rate categories, the higher the probability that alternate P application rates will be recommended due to user variability The results highlight the need for consistent estimation of factor values, particularly the factors to which the P-Index is most sensitive and particularly in the higher-risk situations.
- Comparison of kinetic models to describe high pressure and gamma irradiation used to inactivate Vibrio vulnificus and Vibrio parahaemolyticus prepared in buffer solution and whole oystersHu, X.; Mallikarjunan, Kumar; Koo, J.; Jahncke, M. L. (2005-03-01)
- Precision Farming Tools. Yield MonitorGrisso, Robert D.; Alley, Marcus M.; McClellan, Phil (Virginia Cooperative Extension, 2005-09-01)Using yield monitors is the first step many producers take in precision farming. A yield monitor, combined with Global Positioning System (GPS) technology, is an electronic tool that collects data on crop performance for a given year. To have accurate data for yield map interpretation, the yield monitor must be properly operated and calibrated.