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Marc W. van Iersel and David Gianino

lights on and off at high frequency (10,000 s of times per second). Within each on/off cycle, the fraction of time that the LEDs are on (duty cycle) can be precisely controlled. Reducing the duty cycle creates the perception of dimming, even though in

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Marc W. van Iersel, Geoffrey Weaver, Michael T. Martin, Rhuanito S. Ferrarezi, Erico Mattos, and Mark Haidekker

(top) and a simplified diagram of the duty cycle control board (bottom). A fluorometer is used to measure the quantum yield of photosystem II and the datalogger calculates the electron transport rate from this and the photosynthetic photon flux density

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Matthew Rogoyski, Alvan Gaus, Israel Broner, and Thomas Mourey

An evaporative cooling system for apple trees was implemented. The system is automated to conserve irrigation water. The automation is based on the digital, integrated thermometer and thermostat chip embedded in the artificial fruit. The thermometer–thermostat chip drives a solid state relay. The relay controls a solenoid operated valve. A typical duty cycle consisted of 1 to 2 minutes of wetting (water on) to 4 to 10 minutes drying (water off). Differences in the length of duty cycles between individual chips were observed. The reliability of the system was adequate. The waterproofing of the system's electrical components was its weak point. Irrigation water deposits accumulated on the apple fruit surface during the growing season were readily removable with a simulated brush technique.

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Lauren Fessler, Amy Fulcher, Dave Lockwood, Wesley Wright, and Heping Zhu

. The reason for this difference is that the intelligent spray system controls individual nozzle flow rates with duty cycles of PWM solenoid valves attached to their corresponding nozzles to match sectional canopy foliage volume. To prevent trees from

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Rachel Leisso, Bridgid Jarrett, Katrina Mendrey, and Zachariah Miller

responsible insecticide application, nor as familiar with the codling moth life cycle and appropriate insecticide timing. A simpler management method with potential appeal to small-scale or noncommercial growers combines fruit thinning and bagging early during

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Jianping P. Wang, Suleiman S. Bughrara, and C. Jerry Nelson

development whereby plants, such as desert ephemerals, complete their life cycle before a serious plant water deficit develops. Avoidance involves mechanisms whereby plants maintain high water potential in tissues by maintaining water uptake or reducing water

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Timothy M. Spann, Luis V. Pozo, Igor Kostenyuk, and Jacqueline K. Burns

(Model 3210; Oxbo International). In 2009, the harvester was operated at a ground speed of 0.8 or 1.6 km·h −1 in combination with two shaker head frequencies (185 and 210 cycles/min) for a total of four ground speed × shaker head frequency combinations

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Jen A. Sembera, Tina M. Waliczek, and Erica J. Meier

; Kelway, Wyckoff, NJ), moisture content between 40% and 65%, and temperatures meeting the minimum requirements given the results of the oven mortality tests (Super Duty - Fast Response Windrow Compost Thermometer; Reotemp Instrument Corp., San Diego, CA

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Dan Drost, Taunya Ernst, and Brent Black

duty soil heating cables (Wrap-On Company Inc., Bedford Park, IL) were installed as directed by the manufacturer. Cables were buried ≈2–3 cm below the soil surface and were spaced 30 cm apart. Each cable was attached to a Model 18500 heater controlled

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Britney Hunter, Dan Drost, Brent Black, and Ruby Ward

. Each high tunnel had three 12-m long rows, which were divided into 4-m sections. Soil-warming cables were installed in six of the nine sections in each tunnel after the fertilizer application. Non-automatic heavy duty soil-warming cables (Wrap