Precision Farming
B. Besharati; A. Jafari; H. Mousazadeh; H. Navid
Abstract
IntroductionVarious methods have been performed to control weeds in the world and the use of herbicides is one of them, but public concerns about human health have changed interest in alternative methods. Thermal methods based on flame-weeder, hot air, steam, and hot water have the potential to control ...
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IntroductionVarious methods have been performed to control weeds in the world and the use of herbicides is one of them, but public concerns about human health have changed interest in alternative methods. Thermal methods based on flame-weeder, hot air, steam, and hot water have the potential to control weeds, but due to the high cost are not economical. Electromagnetic waves transfer energy into weeds and finally destroy them. The effect of radiation on plant mutation, high consumption of energy, and human health are problems for this approach. Unlike other methods, electrical energy is an ideal and non-chemical method for weeds. This method applies high voltage to weeds, their roots, and soil so that electric currents pass through them, and the vaporization of the liquid content of weeds kills the weeds. To increase the severity of damage to weeds, the development of a feedback mechanism is required. The ultrasonic sensor measuring physical parameters like plant height is a simple method. Some complex sensing systems include optical sensors such as infrared, and machine vision that require high-speed processors and expensive equipment. In this project, as a simple method, the monitoring of the electrical current passing through weeds was used for developing the feedback mechanism and increasing electric damage to weeds.Materials and MethodsIn this study, the system consisted of a high-voltage device that generated a 15 kV AC voltage to kill weeds, as well as a feedback mechanism that included a sensor to measure the electric current on the input of the weed killer and identify the presence of weeds and their annihilation. All parts were installed on a robotic platform, and an application on a laptop was connected to it via an access point for navigation and data reception. The system was tested in a greenhouse lab with various weeds. Initially, a test was performed to investigate the effect of high voltage on the weeds and establish relationships between the electric currents passing through weeds and their presence (before and after annihilation). During the test, the system was guided along a path and applied high voltage to kill the weeds. The feedback mechanism was then calibrated based on the extracted data on electric current relations. This allowed the system to detect weeds and their annihilation, enabling it to move to the next target once a weed had been eliminated. After calibration, a comparative test was conducted to evaluate the weed-killing efficiency of the two methods (with and without the feedback mechanism), and the results were analyzed using a t-test with p ≤ 0.01.Results and DiscussionThe observations indicated that the input electric current on the weed killer was dependent on the electric current passing through weeds. When the high-voltage electrode touched a weed, the electric current passed through it increased, and simultaneously, the high electrical energy destroyed the weed. After the removal of the weed, the electric current rapidly decreased. The average energy consumption per weed plant was estimated to be 250 joules, which can be compared with other methods. The final test comparing the use and non-use of the feedback mechanism revealed significant differences (P < 0.01) between the results obtained with and without the mechanism, demonstrating that the feedback mechanism increased the efficiency of weed annihilation. The sensing system used in the developed feedback mechanism is a simple method that is affected by the electrical resistivity of weeds. As such, it did not mistakenly detect other objects as weeds, unlike an ultrasonic mechanism. Based on these results, monitoring the electrical current passing through weeds proved to be a suitable method for developing a feedback mechanism for the weed killer to identify the presence of weeds and their annihilation.ConclusionThe use of high voltage as a non-chemical and alternative method for weed control has shown promising results. The study revealed that measuring the electric current applied to the weed killer was an effective and straightforward approach to developing a feedback mechanism. This mechanism aids in identifying the presence of weeds and ensuring their elimination by intensifying the damage inflicted on them through the application of high electrical energy. To further enhance the efficiency and speed of weed control, future research should consider integrating an automatic guidance mechanism with the weed killer.
M. Torkian Boldaji; A. M. Borghaee; B. Beheshti; S. E. Hosseini
Abstract
Introduction Thermal processing has a huge impact on the textural attribute of the final food product and texture is a major factor contributing the overall quality of food. Ohmic heating is an advanced thermal processing method in which heat is internally generated within foods by passing an alternating ...
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Introduction Thermal processing has a huge impact on the textural attribute of the final food product and texture is a major factor contributing the overall quality of food. Ohmic heating is an advanced thermal processing method in which heat is internally generated within foods by passing an alternating electric current through them. Ohmic heating can volumetrically heat the entire mass of a food system, resulting in faster heating, better quality and less energy consumption than conventional thermal processing. Gradient voltage and electrode type have high effect on ohmic heating system. Materials and Methods In this study, the effect of voltage gradient and electrode type on moisture reduction time, a/b, ΔE color indexes and energy consumption were studied. For this purpose, four levels of voltage gradients (5, 7, 9 and 11 V cm-1) and four electrode types (Aluminum, Stainless steel, Brass and Graphite) was investigated by ohmic heating in tomato paste processing. Tomato used in this study was purchased from a local market. The whole tomatoes were washed, crushed and mixed in a way that a red less-viscous liquid obtained (Fig. 1). This liquid was considered as tomato samples in the remainder of the article. Ohmic cooking experiments were conducted in laboratory scale ohmic heating system consists of a power supply, a variable transformer, power analyzer, a microcomputer, digital scale (GF-6000) and thermometer (Dual inpur RTD 804U) (Fig. 3). The ohmic cell had a PTF cylinder with an inner diameter of 0.05 m, a length of 0.10 m and two electrodes on both side of the cell. A hole with 3 mm diameter to insert the thermocouple was created and two holes with 5 mm diameter was created on surface of cell. One of them was used for pouring tomato puree and other for exiting steam from cell. Temperature uniformity was checked during previous heating experiments by measuring the temperatures at different locations in the test cell. Ohmic heating was accomplished till the moisture content of the tomato samples reduced from initial moisture content of as 91(wet basis) to a safer level of 70 (wet basis). Moisture reduction time, a/b and ΔE color indexes, temperature and energy consumption were measured. Results and Discussion The results of the nonlinear mathematical model showed that the effect of different voltage gradient levels on moisture reduction time, ΔE parameters and energy consumption had a good agreement (α≤0.01) as well as voltage gradient had a significant effect on a/b color index (α≤0.05). Electrode type had significant effect on processing time, ΔE (α≤0.01), on energy consumption and a/b index (α≤0.05). Interaction of voltage gradient and electrode type was significant on processing time, energy consumption, a/b and ΔE (α≤0.05). In all electrodes by increasing the voltage gradient, processing time and energy consumption were reduced. For example by increasing the voltage gradient from 5 to 11 V cm-1, processing time and energy consumption were decreased on average 38% and 23%, respectively. Minimal processing time and minimal energy consumption were observed in 11 V cm-1 with graphite electrode that were 17 min and 203 kJ, respectively. As well as maximum processing time and maximum energy consumption were obtained in 5V cm-1 with aluminum electrode that were 105.21 min and 321 kJ, respectively. But maximum a/b parameter and minimal ΔE index were observed with stainless steel electrode in 11V cm-1. In determining the best electrode, in addition to the processing time and energy consumption, product quality is also an important parameter. However, graphite electrode has better performance in terms of time and energy consumption, but stainless steel electrode has better performance in term of product quality. Since the production of food, quality is an important parameter, and also the two electrodes graphite and steel are similar in terms of energy consumption and processing time, but stainless steel electrode is better in term of quality, so stainless steel electrode is selected for ohmic heating tomato paste. Conclusion Different voltage gradients and Electrode type have a significant effect on processing time, energy consumption, ΔE and a/b color indexes. Minimal processing time and minimal energy consumption were observed in 11 V cm-1 with graphite electrode that were 17 min and 203 kJ, respectively. But maximum a/b parameter and minimal ΔE index were observed with stainless steel electrode in 11V cm-1. Stainless steel electrode and 11 V cm-1 voltage gradient were the best condition for tomato paste processing by ohmic heating.
