This study investigates the effectiveness of periodic stirring as a non-chemical approach to suppress maize weevils, Sitophilus zeamais, and other beetle populations in large-scale grain storage bins. The research was conducted in a farm steel bin with a diameter of 9.8 m holding 127 Mg of maize, and a control bin of diameter 7.3 m holding 102 Mg of maize. Both bins were loaded with maize at 13% moisture and infested at a commercial tolerance rate of 2 weevils/kg of maize. Probe traps monitored beetle populations except for S. zeamais before stirring was initiated. Maize samples were collected at depths of 0, 0.9, 1.8 and 2.7 m with a vacuum-probe sampler prior to stirring and at 10, 20, 30 and 40 days of continuous stirring machine operation. Stirring achieved 100% control of live S. zeamais while the control bin experienced an increase in its S. zeamais population after 40 days. The stirring process also led to a significant reduction in dominant beetle populations such as hairy fungus beetles, Typhaea stercorea, and foreign grain beetles, Ahasuerus advena. Although the quality of maize in both bins changed at different depths and storage times, the treatment bin had higher bulk density (732.7 +/- 3.98 kg/m(3) to 768.9 +/- 2.41 kg/m(3)), lower insect damage (0.02 +/- 0.02% to 0.9 +/- 0.28%), and higher allowable storage time (>249 days). Moisture content and molded kernels increased in the control bin, reaching 26.4 +/- 1.29% and 3.2 +/- 0.53%, respectively. The average percentage of broken corn and foreign material (BCFM) in the sweepings on the floor of the emptied treatment bin was 6.5 times higher than that in the control bin. Calculated packing factor values below 1.5 from the sweepings indicated that BCFM concentrations did not affect airflow. Stirring maize provides an alternative to the use of chemicals to control stored maize insect pests at a production scale.

Sitophilus zeamais Motschulsky threaten maize (Zea mays L.) storage in the tropical regions of low-income countries where maize is a staple. Disturbance of maize during storage can be an alternative to chemical treatment in suppressing populations of S. zeamais. Disturbance has been successful against insect pests of stored products, i.e. bean weevils, Acanthoscelides obtectus (say) (Coleoptera: Chysomelidae: Bruchinae) and lesser grain borers Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). Prior research has not established a standard disturbance interval. This study tested various disturbance intervals to see determine suppression of S. zeamais populations in stored maize with four treatments: stationary jars (control) and jars disturbed at intervals of 8, 12 and 24 h. Jars contained 1 kg of 16 +/- 0.7% wet basis moisture maize and 234 +/- 51 adult S. zeamais stored at 27 degrees C, 70% r. h. and 12 h light and dark phases. Periodically, electric motors rotated jars through about 1.25 revolutions in 3 s. Three jars were selected randomly from each treatment every 40 d up to 160 d for analysis. Reduction in S. zeamais populations was 75%, 95% and 94% for 8, 12 and 24 h disturbance intervals, respectively, compared to the stationary jars after 160 d. The average quality of maize in all disturbed jars was better than in stationary jars, respectively, for moisture content (13 +/- 1.1% vs. 21 +/- 1.0%), bulk density (553.5 +/- 1.1 kg/m3 vs. 231.7 +/- 1.2 kg/m3), broken corn and foreign material (9 +/- 1.2% vs. 68 +/- 3.9%), insect damage (70 +/- 4.5% vs. 100 +/- 0.0%), and mold damage (0.4 +/- 0.2% vs. 27 +/- 17.2%). Disturbances of 12h and 24 h (once per day) proved the best intervals in suppressing S. zeamais populations and maintaining the quality of maize, much longer than previously reported. Of these two intervals, the less frequent 24 h disturbance interval may be an effective non-chemical approach to control S. zeamais in maize stored by smallholder farmers, requiring less effort.

Chilled aeration allows to cool grain, independent of ambient conditions, to "safe" temperatures where insect, fungi, and spoilage is reduced to the minimum. The objective of this research was to evaluate the advantages of using grain chilling to preserve the quality of grain and reduce post-harvest losses, compared to conventional aeration and storage strategies used during the summer storage of wheat in Central Kansas, U.S.A. The research trials were developed in two 1,350 metric ton (t) steel silos in a Farmer’s Cooperative during the summer and fall of 2015 and 2016. One of the silos was chilled and the other was used as a control managed by the Cooperative. Variables evaluated were: grain temperature, moisture content (MC), grain quality, insect development and reproduction rate. The chilling treatment reduced the grain temperature from 28°C- 39°C to a minimum of 17°C- 17.6°C in less than 250 hours. Grain temperatures below 25°C were not possible during the summer using ambient aeration. Minimum variation of MC was observed in the Chilled silo while ambient aeration reduced the MC by 0.5%. Reproduction rates of RFB and LGB were significantly reduced by chilled temperatures lower than 17°C. Lower temperatures also reduced insects discovered in probe traps and insect damaged kernels (IDK). The energy cost of the grain chiller was between 0.26 US $/t- 0.32 US $/t higher than ambient aeration.

The forces required to extricate a test mannequin from a grain mass when buried at different depths with and without a grain restraint system were determined. When there was no grain restraint system in place, the vertical force required to pull the mannequin from the grain when it was buried waist deep and to the underarms was 1259 and 1766 N (283 and 397 lbf), respectively. It increased to 1584 N (356 lbf) (+ 26%) and 2153 N (484 lbf) (+ 22%), respectively, with the restraint in place due to the changes in grain properties brought about by the insertion of the rescue tube. It was concluded that the use of a grain restraint during extrication of a victim does not reduce the forces required and that forcefully pulling an entrapped victim, especially with mechanical assistance, with or without a grain restraint system could result in severe injuries and possible death due to the forces exerted on the victim. The authors recommend that these findings be incorporated into current grain extrication training for emergency first responders.

The feasibility of utilizing cellulosic biomass such as corn stover as an energy feedstock is dominated by factors such as facility location, feedstock availability, and transportation cost. Previous research showed the advantages of using a GIS-based method compared to a previously used concentric ring buffer method. Even though the GIS-based method proved to be more accurate because it precisely calculates the distance from the facility to the farms using a real road network and the hectares of crop-specific fields in a given service area, opportunities exist to further improve its accuracy. In this case study, two improvement parameters were implemented to the previously proposed GIS-based method to examine the effect of field-level yield variance and variable residue removal rates on the quantification of feedstock availability for a biorefinery. The new variable residue removal (VRR) method predicted on average 113,384 +/- 38,770 dry tons (DT) of additional residue per service area compared to the previous constant residue removal (CRR) method. The use of a constant removal rate of 3 DT ac(-1) in the CRR method clearly underestimated feedstock availability, given that residue removal rates are highly variable and subject to location, erosive forces, soil characteristics, crop type, yield, and field management. However, to prevent soil erosion and maintain soil productivity, conservation tillage practices require that at least 30% of the soil surface must be covered with residue after planting the next crop. Even with a reduction in total feedstock availability, the VRR method estimated comparable residue availability per service area to the CRR method, with only a 4 +/- 6% decrease per service area on average. Consequently, the VRR method turned out to be the preferred approach in the quantification of biomass feedstock availability.

A 3D transient heat, mass, momentum, and species transfer model for the stored grain ecosystem was developed using the finite element method. Hourly weather data such as ambient temperature and relative humidity, solar radiation, and wind speed were used as input in the model. The 3D model has different components that predict grain temperature and moisture content, dry matter loss, insect population, and species (CO2 and fumigant) concentration. The 3D model was evaluated using linear elements with three different numbers of nodes and quadratic elements with three different numbers of nodes. The accuracy of prediction for each category was evaluated using the observed and predicted temperature values. The linear model with 384 nodes and the quadratic model with 415 nodes were found to be the best based on the lowest standard error compared to other combinations. Four different time discretization schemes were used to evaluate model accuracy over time. The Crank-Nicolson time discretization scheme was found to be the best of the four.

Scale-up demonstration trials were conducted at the pilot bin facility of the Purdue University Post-Harvest Education and Research Center in June 2005, August 2006, July 2007, and October 2008 with conventional yellow maize and at a popcorn storage facility in July 2005 and 2006. The primary objective of these trials was to determine the efficacy of ozonation to control insect pests without affecting end-use quality. The setup consisted of generating ozone at a constant rate with commercially available generators, introduction in the headspace, drawdown to the plenum with a fan with a minimum air velocity through the grain of 0.03 m/s, re-circulation back into the headspace or exhausting from the plenum into another bin. Ozonation was done to attain an ozone concentration of 50 ppm in the plenum to be maintained for a period of 72 h (3,600 ppm-h). When this concentration was not achieved, an ozone concentration-time product of 3,600 ppm-h was aimed for extending the time to expose the grain mass to the same treatment effect to achieve 100% insect mortality. The trials were performed using insect bioassays with adults of maize weevil (MW) and red flour beetle (RFB). Insect mortality was essentially 100% for both MW and RFB. The concept of two phases of ozonation and the airflow rates needed to achieve the required treatment levels of 3,600 ppm-h were investigated. The trials at the popcorn facility confirmed that end-use parameters of popcorn were not affected.

Three-dimensional heat and momentum transfer for the peaked, leveled, and inverted cone grain mass configurations in a corn silo was studied with aeration airflow rate ranged from 0.26 to 0.31 m(3)/min-t (0.24 to 0.28 cfm/bu) using the 3D finite element stored grain ecosystem model. Non-uniform airflow models for peaked, leveled, and inverted cone grain mass configurations were developed using the finite volume method. Airflow resistance due to porous media of grain material was implemented using Ergun's equation and a linear porosity variation with low porosity at the center and maximum at the side. The velocity profile and heat transfer during aeration were quantified for the peaked, leveled and inverted cone grain mass configurations. The change in grain temperature in the inverted cone grain mass configuration was the fastest followed by the leveled and peaked configurations. It took 102, 114, and 186 h, respectively, for cored, leveled, and peaked grain mass configurations to cool the grain from 40 degrees C to below 20 degrees C. For the peaked cone volume, the model predicted an 84-h delay in the cooling front movement (or about 55%) compared to the inverted cone configuration. This has significant implications with respect to fan run time hours, electricity consumption, and the potential for grain spoilage.

This study was conducted to quantify the forces required to insert the individual panels of a grain rescue tube into four grains of varying moisture contents. The study was conducted to address issues raised by emergency rescue personnel involved with extrication of victims entrapped in grain using a fabricated or commercially available grain containment system. These rescue aids are used to separate or protect the victim from the grain mass, enabling safe rescue. Conclusions drawn from the study included documentation that as the moisture content of the grain increases, the amount of resistance against tube insertion increases substantially. It was found that although the moisture content may be similar across several types of grain, the amount of work required to insert a rescue tube into the grain can vary. It was also concluded that the cohesiveness, angle of internal friction, and static coefficient of friction of the grain on the tube surface, which vary with moisture content and type of grain, were primary factors affecting the amount of effort needed to insert the tube. This article recommends that a consensus standard be developed covering the design and testing of grain rescue tube containment systems.

Entrapment in flowable agricultural material continues to be a relevant problem facing both farmers and employees of commercial grain storage and handling operations. While considerable work has been done previously on the causes of entrapment in grain and possible preventative measures, there is little research on the efficacy of current first response or extrication techniques. With the recent introduction of new grain rescue equipment and training programs, it was determined that the need exists to document and summarize prior grain rescue strategies with a view to develop evidence-based recommendations that would enhance the efficacy of the techniques used and reduce the risks to both victims and first responders. Utilizing the Purdue University Agricultural Entrapment Database, all data were queried for information related to extrication of victims from grain entrapments documented over the period 1964-2006. Also analyzed were data from other sources, including public records related to entrapments and information from onsite investigations. Significant findings of this study include the following: (1) between 1964 and 2006, the number of entrapments averaged 16 per year, with the frequency increasing over the last decade; (2) of all cases documented, about 45% resulted in fatality; (3) no less than 44% of entrapments occurred in shelled corn; (4) fatality was the result in 82% of cases where victims were submerged beneath the grain surface, while fatality occurred in 10% of cases where victims were only partially engulfed; (5) the majority of rescues were reported to have been conducted by untrained personnel who were at the scene at the time of entrapment; and (6) in those cases where the rescue strategies were known, 56% involved cutting or punching holes in the side walls of the storage structure, 19% involved utilizing onsite fabricated grain retaining walls to extricate partially entrapped victims, and the use of grain vacuum machines as a rescue strategy was on the increase. Among the recommendations growing out of the study are these: (1) conduct further tests on the efficacy of grain rescue strategies, including the use of recently introduced grain rescue tubes and grain vacuum machines; (2) incorporate the findings into future first responder training programs; and (3) enhance the first response skills of personnel working at grain storage facilities, both on-farm and at commercial operations.

The feasibility of utilizing cellulosic biomass such as corn stover as an energy feedstock is dominated by factors such as facility location, feedstock availability, and transportation logistics. This study compares two methods to quantify feedstock availability given a facility's location using a geographical information system (GIS). The purpose is to highlight the advantages of using the proposed method (method 2) compared to a previously developed method (method 1). Method 1 is a straightforward approach in which the distance from the facility to the farm fields is first estimated and then hectare availability per service area is calculated using USDA-NASS statistics. Method 2 determines hectare availability by using geospatial images from which a service area is created based on a detailed road network dataset and a crop data layer. This method proved to be more accurate because it calculates the distance from the facility to the farm fields using a real road network and uses hectares of crop-specific fields in a given service area based on crop season-specific satellite images. Method 1 overestimated hectare availability per service area by 14,374 ha (35,518 ac; a factor of 1.45) on average, giving the false impression that a facility's annual feedstock requirement can be met within a shorter distance and with presumably lower transportation costs. The proposed GIS-based methodology will allow more reliable prediction of a feedstock supply area for existing or planned biomass-based processing facilities.

A novel deep-bed solid-state bioreactor was designed and fabricated for cellulolytic enzymes production using mixed fungal cultures. Better temperature and moisture control was achieved through a unique bioreactor design comprising an outer wire-mesh frame with internal air distribution along with near-saturation conditions within the cabinet. Without airflow through the internal distributors, maximum temperatures of 48 degrees C and 52 degrees C were observed during half- and full-capacity operation. These were reduced to 44 degrees C and 43 degrees C on resumption of airflow. In terms of cellulolytic enzyme production, no significant differences occurred in filter paper activity with depth in half-capacity operation; however, in full-capacity operation, top-level filter paper activity (5.39 FPU/g-solids) was significantly different from middle- and bottom-level activity. Top level beta-glucosidase, endocellulase, and xylanase activities were significantly (P < 0.05) different from middle and bottom levels in both half- and full-capacity operation. A two-phase coupled heat and mass transfer model was developed that predicted the experimental trends reasonably well. Model predictions confirmed that cabinet temperature of 30 degrees C and distributor airflow rate of 3.42 kg h(-1) during operation enabled effective temperature control. (C) 2011 Elsevier B.V. All rights reserved.

Ambient aeration is typically used in temperate climates to preserve grains by cooling, preventing moisture migration, and maintaining temperature as low and uniform throughout the grain mass as possible. However, the climatic factors for wheat bulk storage in the sub-tropical climate of north India are challenging for the grain preservation process. Low relative humidity with high temperature during daytime and high relative humidity with low temperature during nighttime is the common phenomenon. Five years of weather data were analyzed using the modified Chung-Pfost EMC equation for wheat. Fifteen different aeration strategies were formulated based on the weather data during the maintenance period (June to September) and cooling period (October to March). Strategies were selected based on combinations of the following parameters: temperature control; EMC control; 1 h, 2 h, or 4 h morning and/or evening aeration; and 0.11, 0.34, and 0.67 m(3) min(-1) t(-1) airflow rate. These 15 aeration strategies for the sub-tropical weather conditions of north India were studied using the 2D PHAST-FEM model developed at Purdue University. The initial grain temperature and moisture were assumed as 27 degrees C and 12% (w.b.), respectively, based on typical harvest conditions. Dry matter loss (DML), insect development, fan run hours, and average grain temperature and moisture content for these aeration strategies were quantified based on weather data from 2000-2001 to 2004-2005. Aeration strategies were selected based on the optimum combination of low values of DML, insect development, grain temperature, moisture content, and fan run hours during both the maintenance and cooling periods. The best strategy was to operate fans 4 h during the morning and evening with an airflow of 0.11 m(3) min(-1) with EMC control but without temperature control during the maintenance period and with both EMC and temperature control during the cooling period (strategy 13).

Non-uniform airflow models for peaked, levelled and cored grain mass configurations in a maize silo were developed using the finite volume method. Airflow resistance due to porous media of grain material was implemented using Ergun's equation. The linear porosity variation was implemented with low porosity at the centre and maximum at the side. Non-uniform airflow distribution for natural air drying with an airflow rate of 1.1 m(3) min(-1) t(-1) was validated with experimental data using maize in grain bins with storage capacities of 180.0-450.0 Mt. Air velocity was predicted with reasonable accuracy for cored, levelled and peaked grain mass configurations having porosities ranging from 0.34 in the core to 0.38 towards the silo wall. Incorporation of variable porosities into the model improved the air velocity prediction. For the cored grain mass and variable porosity (0.34-0.38), the error was 4.4% at the centre and 23.1% at the periphery. (C) 2011 IAgrE. Published by Elsevier Ltd. All rights reserved.

During storage, headspace conditions play an important role in affecting the physical, chemical, and biological activities of living organisms in the upper layer of a grain mass. A model was developed using energy and mass balance principles to predict temperature and relative humidity of the headspace air in a partially filled silo. The formulation of the headspace domain had nine control volumes (nine temperatures and RH values) with the grain and roof surfaces as boundaries. Solar radiation and convective heat transfer were used as the driving factors for heat transfer in the headspace. Humidity transfer due to the air mass flow rate was considered the driving factor behind changes in headspace RH. The periodic changes in solar radiation and wind speed induced temperature and humidity variations in the silo headspace. The predicted results were validated using observed data. The standard error of predicted versus observed headspace air and wall temperatures was in the range of 2.3 degrees C to 5.3 degrees C and 3.1 degrees C to 5.5 degrees C, respectively. The standard error of predicted versus observed headspace humidities was around 7%. The developed model is considered sufficiently accurate and reliable to predict air temperature and relative humidity at multiple locations in the headspace of a grain storage silo.

Insects can cause substantial damage to stored grain. In addition, consumers and therefore food processors are increasingly interested in chemical-free products. Integrated pest management (IPM) may increase farmers' profits while reducing their use of pesticides. This study uses a stochastic dynamic programming framework to model the economics of optimal insect control in corn, Zea mays L., stored on-farm with multiple controls conditional on the biophysical conditions of the grain in the bin. We find that for farmers who have a contract with a food processor, where there are quality premiums, the optimal management strategy depends on monitoring the biophysical conditions of the grain and the time period under consideration. For farmers who deliver to the commodity market, their current practices are optimal.

In this study, pressurization tests were conducted to quantify gas-tightness of the Hal Ross Flour Mill at Kansas State University, which was sealed at three sealing qualities, i.e., fully sealed, partially sealed, and non-sealed. A computational fluid dynamics (CFD) model of the mill was then constructed. Based on the building gas-tightness levels obtained from the pressurization tests, several sulfuryl fluoride fumigations were simulated to study sensitivities of the half-loss time (HLT) and concentration x time (Ct) product of the mill as affected by sealing quality, and wind and buoyancy forces. The HLT of the fully sealed simulation case was at least two to three times greater than that of the partially and non-sealed cases, respectively. The Ct product results followed a similar trend. The results of this study emphasized the importance of the pressurization test as a useful tool for quantification of building gas-tightness and for prediction of expected HLT and Ct product of a subsequent structural fumigation.