September 15, 2016

Automated solid state canopy delivery (SSCD) system to deliver mist-cooling to increase winter chill for dormancy and bud break

California growers in the San Joaquin Valley believe that climate change will affect the dormancy of pistachio and the yield dramatically. As the central valley fog disappears, the dormancy of pistachio is severely influenced. Sustained sunlight warms the buds and decreases chill accumulation. If the accumulated chill is not sufficient for dormancy release and bud break the result is abnormal flowers, poor bloom synchrony, high rates of blanks and low yields.

In this project, we introduce an environmentally friendly and high cost-performance method to cool down the bud temperature on sunny days to avoid chill offset. This system includes: (i) an automated solid state canopy delivery (SSCD) system which mists the trees giving very uniform coverage; (ii) wireless weather-, crop-related data (air temperature, air humidity, etc.) acquisition system; and (iii) a smart control system.

The main goal of this system is to maximize evaporative cooling effect of the water, while minimizing the amount used. We have developed, deployed and evaluated the SSCD system in a commercial pistachio orchard in Bakersfield, CA. This system will help California growers to further understand the chilling requirements for pistachio.

September 15, 2016

Development of an intelligent irrigation system using fuzzy logic and wireless sensor network

In our preliminary results, we have developed an intelligent irrigation system (first prototype) using WSN and two fuzzy logic controllers (embedded system). The WSN contains various sensors, such as soil moisture, air temperature, solar radiation etc. All these linguistic variables are fuzzified using triangular and trapezoidal pertinence functions. The fuzzification interface was defined using Max-Min and Mamdani Minimum engine. Two fuzzy controllers were developed to efficiently: (i) set the time and duration of irrigation, control a valve, and optimize irrigation scheduling; (ii) set the time intervals to acquire data from the sensor for better energy management. The second fuzzy controller was used to reduce the usage of battery power. Because the WSN must be deployed in the field, the sensors were powered by rechargeable batteries, which can be supplied by a renewable energy source such as solar panels. Additionally, a power saving sleep mode was implemented to power down the WSN. The second fuzzy controller, based on appropriate fuzzy rules, could trigger an overflow interrupt and activate the microcontroller from the sleep mode. This system is easy to deploy in various irrigation systems and compensates the amount of water that is lost through evapotranspiration for a given crop. Although we have not yet tested this system in a field, simulation studies have yielded promising results and have demonstrated the feasibility of fuzzy logic control in this application.

September 15, 2016

Wireless Sensor NetworkFor Measuring Flood Irrigation

Flood Irrigation is a commonly used practice that is performed in order to deliver water to fields for a variety of crops, ranging from Alfalfa to Almond trees. In order to optimize how much water is applied to a field, it is necessary to calculate a Distribution Uniformity (DU). DU is a parameter used to calculate irrigation efficiency. DU is much easier to calculate than the overall efficiency, and fortunately provides good information for how well an irrigation system is functioning. DU states how well water is applied throughout the entire field, with an ideal DU being 100%. A DU of less than 100% means that more water must be applied to the field in order for the entire area of the field to be irrigated. One of the parameters that needs to be measured in order to calculate DU is the opportunity time, or the amount of time it takes for the flood wave to arrive at specific lengths of a field. Existing methods to obtain such data requires personnel to physically watch the flood wave and note the time. In some cases, Flood Irrigation can take up to 24 hours which makes this technique exhausting and inconsistent. Due to these inconsistencies and not properly understanding the DU, may lead to "overwatering" or not providing enough water. The "overwatering" creates a tail run-off, which means the excess water runs off the end of the field and is recirculated back to the front of the field, where it is either reapplied to the field or stored in a reservoir. By not knowing the DU, this tail water recirculation may or may not be necessary. By evaluating the opportunity time, one can know if actions will needed to be taken in order to improve DU, such as deep ripping, cross checks, and of course tail water recirculation.

Our goal is to design and develop a wireless sensor network that will measure the time of arrival and departure of a flood wave at predefined intervals. This data will then be compiled in order to calculate DU, which will ultimately minimize (optimize) the amount of water applied to a field, in turn saving water, energy, and money for the farmer.