Bioresource and Agricultural Engineering Copyright (c) 2013 California Polytechnic State University All rights reserved. http://digitalcommons.calpoly.edu/bae_fac Recent documents in Bioresource and Agricultural Engineering en-us Wed, 01 May 2013 13:15:45 PDT 3600 Velocity Contour Weighting Method. II: Evaluation in Trapezoidal Channels and Roughness Sensitivity http://digitalcommons.calpoly.edu/bae_fac/104 http://digitalcommons.calpoly.edu/bae_fac/104 Fri, 17 Feb 2012 12:48:47 PST The Velocity Contour Weighting Method (VCWM) was developed in Part I to accurately estimate the cross-sectional average velocity of a prismatic channel flow using acoustic Doppler velocity meter (ADVM) measurements of centerline velocity. Here, the VCWM is validated by its successful application to 25 different concrete-lined trapezoidal channels used for irrigation water delivery. At each site, the cross-sectional distribution of velocity is measured by an acoustic Doppler velocimeter (ADV), which is moved horizontally and vertically through a sampling grid. Multiple tests at some sites led to a total of 51 sets of cross-sectional measurements. ADVM measurements are simulated by interpolating ADV measurements along a set of vertically aligned centerline coordinates typical of ADVM deployments. Subsequent application of the VCWM gives an estimate of the cross-sectional average velocity. Secondly, the velocity-area method is applied to the ADV data to directly measure the cross-sectional average velocity for comparison with the VCWM estimate. Based on this comparison, relative percent errors in the VCWM for all 51 tests were within ±6:3% using a probable surface roughness (ks) for the finished concrete of 0.0006 m without calibration. A sensitivity analysis shows that a range of realistic roughness values for finished concrete can be used without degrading the accuracy of the cross-sectional average velocity predictions by more than an additional ±1%. Hence, the method is relatively insensitive to poorly characterized roughness values.

]]> Daniel Howes et al. Velocity Contour Weighting Method. I: Algorithm Development and Laboratory Testing http://digitalcommons.calpoly.edu/bae_fac/103 http://digitalcommons.calpoly.edu/bae_fac/103 Fri, 17 Feb 2012 12:48:36 PST An algorithm is developed for real-time estimation of the cross-sectional average velocity of a channel flow by using an upward-looking pulsed wave acoustic Doppler velocity meters (ADVM). The Velocity Contour Weighting Method (VCWM) is applicable to gradually varied flows in prismatic channels and requires little to no calibration. VCWM estimates the average velocity as a weighted average of ADVM bin velocities. Weights are based on the velocity distribution sampled by the ADVM. Collectively, the VCWM is able to adapt to a wide range of channel geometry and roughness features. Expressions for the velocity weights are developed by first applying a validated 3D computation fluid dynamics (CFD) channel flow model to a wide range of flow scenarios including differing channel geometries, discharge rates, depths, and boundary roughness. CFD simulation data are then reduced empirically with the aid of dimensional analysis to obtain the velocity weight equation. Special attention is given to the first weight accounting for near-wall velocity where the ADVM does not measure. Application of the method to a large rectangular flume shows that the VCWM predicts the average velocity with an uncertainty less than ±5% and that this uncertainty can be reduced by minimizing the buffer distance between the channel bottom and the first velocity measurement. In a companion paper, the performance of the VCWM is examined in irrigation canals with trapezoidal cross sections.

]]> Daniel J. Howes et al. Spray Drift Reduction with Shrouded Boom Sprayers http://digitalcommons.calpoly.edu/bae_fac/102 http://digitalcommons.calpoly.edu/bae_fac/102 Fri, 09 Sep 2011 12:07:06 PDT Downwind drift was measured from a standard boom sprayer and a shrouded boom sprayer. Using 8002 flat fan nozzles, the hooded sprayer provided a 180 to 275% reduction in drift. The effectiveness of the shroud is dependent upon the spray droplet spectrum.

]]> Ronald J. Fehringer et al. Guarding Against Machine Hazards http://digitalcommons.calpoly.edu/bae_fac/101 http://digitalcommons.calpoly.edu/bae_fac/101 Fri, 09 Sep 2011 12:07:02 PDT Successful guarding strategies requires knowledge of machine functions, the physical and psychological characteristics of man, and the their interactions. Machine hazards are identified along with recognized guarding methods. Material is included that could be used to teach this subject (case study, prob!em set, glossary}.

]]> R. A. Cavaletto Evaluating Strength & Energy Requirements for Workers Picking Vegetables http://digitalcommons.calpoly.edu/bae_fac/100 http://digitalcommons.calpoly.edu/bae_fac/100 Fri, 09 Sep 2011 12:06:58 PDT The paper discusses the need to obtain field data to evaluate the strength and energy requirements for workers picking a variety of vegetables. This information is central to the evaluation of hazards related to repetitive motion, excessive stress, and fatigue. Results can be used to select activities which should be targeted for future engineering design projects. Preliminary data from a commercial broccoli harvesting operation is included.

]]> R. A. Cavaletto et al. Method for Stemming Tomatoes http://digitalcommons.calpoly.edu/bae_fac/99 http://digitalcommons.calpoly.edu/bae_fac/99 Fri, 09 Sep 2011 12:06:53 PDT Method and apparatus for de-stemming picked tomatoes. Each tomato is introduced into the upper end of a generally vertically disposed, open-ended, resilient, open-mesh fabric tube, a substantial portion of which approximates but is larger than the diameter of the tomato. The stem penetrates into and through the open mesh at some point, the open areas being somewhat larger than the stem, while the tomato continues to fall, thereby exerting a bending moment on the stem that snaps the stem from the fruit. The tomato, free from its stem, is discharged from a lower end of the tube.

]]> Henry F. Studer et al. Guarding of Table Saws with Light Beams: The Light Guard Concept http://digitalcommons.calpoly.edu/bae_fac/98 http://digitalcommons.calpoly.edu/bae_fac/98 Fri, 09 Sep 2011 12:06:49 PDT This paper describes a unique type of psychological safety guard for hazardous tools such as table saws, presses. and other tools with areas and components which are dangerous to human fingers, hands, and limbs. It is not a piece of hardware but rather a shalt of light which defines a danger zone around the saw blade or cutting area.

]]> R. A. Cavaletto et al. A Light Transmission Model for Biological Materials http://digitalcommons.calpoly.edu/bae_fac/97 http://digitalcommons.calpoly.edu/bae_fac/97 Fri, 09 Sep 2011 12:06:45 PDT This paper describes a model to predict light transmission in biological materials. The model can be used for any shaped sample. Scattering and absorption coefficients are used in the model and may be varied throughout the sample, thus allowing both uniformly distributed and concentrated defects to be modelled.

]]> R. A. Cavaletto et al. Evaluation of Two Models for Light Transmission in Biological Materials http://digitalcommons.calpoly.edu/bae_fac/96 http://digitalcommons.calpoly.edu/bae_fac/96 Fri, 09 Sep 2011 12:06:41 PDT Two light transmission models for biological materials are developed and evaluated. The energy balance model showed promise. It's developed as a 3 coefficient model permitting varied sample absorption and scattering properties. The second model performed unsatisfactorily.

]]> R. A. Cavaletto et al. Subcritical Contraction for Improved Open-Channel Flow Measurement Accuracy with an Upward-Looking ADVM http://digitalcommons.calpoly.edu/bae_fac/95 http://digitalcommons.calpoly.edu/bae_fac/95 Wed, 06 Jul 2011 13:34:53 PDT Acoustic Doppler velocity meters (ADVMs) provide an alternative to more traditional flow measurement devices and procedures such as flumes, weirs, and stage rating for irrigation and drainage canals. However, the requirements for correct calibration are extensive and complex. A three-dimensional computational fluid dynamics (CFD) model was used to design a subcritical rapidly varied flow contraction that provides a consistent linear relationship between the upward-looking ADVM sample velocity and the cross-sectional average velocity in order to improve ADVM accuracy without the need for in situ calibration. CFD simulations validated the subcritical contraction in a rectangular and trapezoidal cross section by showing errors within +1.8 and -2.2%. Physical testing of the subcritical contraction coupled with an upward-looking ADVM in a large rectangular flume provided laboratory validation with measurement errors within +-4% without calibration.

]]> Daniel Howes et al. Tailwater Recovery Demonstration Program Srrudy http://digitalcommons.calpoly.edu/bae_fac/94 http://digitalcommons.calpoly.edu/bae_fac/94 Thu, 06 Jan 2011 13:53:53 PST Doug Welch et al. Broad-Crested Weir Application on 15,000-Acre Farm http://digitalcommons.calpoly.edu/bae_fac/93 http://digitalcommons.calpoly.edu/bae_fac/93 Thu, 06 Jan 2011 13:53:51 PST Growers in California have been subjected to increasing pressure to account for water used on the farm due to limited water supplies and increasing energy costs. Water measurement capability provides for equitable distribution of assigned costs and enables effective water management to be accomplished. Broad-crested weirs are proven water measurement devices, especially when applied to on-farm applications. The broad-crested weirs and published data were developed by the USDA Agricultural Research Service in Phoenix, Arizona. This paper is a discussion of an application of these weirs.

]]> Stuart W. Styles Irrigation Methods For Drainage Reduction Subsurface Drip vs. Furrow Irrigation http://digitalcommons.calpoly.edu/bae_fac/92 http://digitalcommons.calpoly.edu/bae_fac/92 Thu, 06 Jan 2011 13:53:48 PST J.. D. Oster et al. Grassland Basin Irrigation and Drainage Study http://digitalcommons.calpoly.edu/bae_fac/91 http://digitalcommons.calpoly.edu/bae_fac/91 Thu, 06 Jan 2011 13:53:45 PST This paper summarizes a project that analyzed the district irrigation efficiency for six subareas of the Grassland Basin roughly representing 80,000 acres on the west side of the San Joaquin Valley near Firebaugh, California. The objectives of this project were to:

• Determine the district irrigation efficiency for the six subareas.

• Update district drainage policies and water reuse.

• Update the geographical information system (GIS).

• Perform a pre-plant irrigation efficiency analysis.

• Establish a relationship between the drainage volumes and the district irrigation efficiency.

• Determine the maximum district irrigation efficiency attainable.

• Determine the impact of optimizing district irrigation efficiency on loads and concentrations leaving the districts.

]]> Stuart W. Styles et al. Incorporation of Reservoirs into Irrigation Supply Systems to Simplify Flexible Operations http://digitalcommons.calpoly.edu/bae_fac/90 http://digitalcommons.calpoly.edu/bae_fac/90 Thu, 06 Jan 2011 13:53:43 PST John L. Merriam et al. Improving Water Properties to Increase Infiltration Characteristics http://digitalcommons.calpoly.edu/bae_fac/89 http://digitalcommons.calpoly.edu/bae_fac/89 Thu, 06 Jan 2011 13:53:40 PST Water properties, such as the viscosity and surface tension, can be affected by temperature and surfactants to Increase infiltration rates into soils. Specifically, they will change the hydraulic conductivity of the soil. A simple soap solution and the new material PAM (inexpensive polymer chemical) were evaluated as surfactants. Laboratory experiments and field tests on a site in Davis, California were done to quantify the effects of changing the water properties. Additional effects, like the improved soil structure during infiltration and less soil particles in tailwater (reduced erosion due to runoff) were observed and are described in this paper. The conclusions of this study are translated into suggestions for improved on-farm water use in furrows, sprinklers, and drip irrigation.

]]> Richard W. O. Soppe et al. Evaluation of Micro Irrigation Systems http://digitalcommons.calpoly.edu/bae_fac/88 http://digitalcommons.calpoly.edu/bae_fac/88 Wed, 15 Dec 2010 08:50:33 PST Charles M. Burt et al. Water Seepage From Unlined Ditches and Reservoirs http://digitalcommons.calpoly.edu/bae_fac/87 http://digitalcommons.calpoly.edu/bae_fac/87 Wed, 15 Dec 2010 08:50:29 PST Seepage losses in the San Joaquin Valley's Westlands Water Districts were estimated at 27,000 acre-feet a year, or about 2% of the district's water supply. Ditch configuration and construction techniques appear to influence seepage rates.

]]> Nigel W.T. Quinn et al. Sizing of Header and Flushing Manifolds for Row Crop Drip http://digitalcommons.calpoly.edu/bae_fac/86 http://digitalcommons.calpoly.edu/bae_fac/86 Wed, 15 Dec 2010 08:50:26 PST Charles M. Burt et al. Drip Irrigation Technology: A Resource Management Tool for Farmers http://digitalcommons.calpoly.edu/bae_fac/85 http://digitalcommons.calpoly.edu/bae_fac/85 Wed, 15 Dec 2010 08:50:23 PST John C. Roberts et al.