Electrical Conductivity Measurement System Research Articles

Development of a soil electrical conductivity measurement system in paddy fields

This study aims to develop a data collection system for measuring soil electrical conductivity (EC) in Paddy Fields using the Wenner measurement principle, with one electrode configuration based on the Veris 3100 measuring machine, and a second electrode configuration with fixed electrodes. The result is a system that measures soil EC using the fixed electrode configuration for more stable results compared to the coulter electrode configuration on the Veris 3100. This system comprises three main components: a 7-inch industrial touchscreen monitor used for real-time monitoring and storing collected data on external memory, a controller that provides reverse direct current (DC) power supply to the electrodes and measures voltage and current parameters on the electrodes, two mechanical configurations including six electrodes in contact with the soil. The system is developed to operate best after soil preparation and before seed sowing. The collected data is processed and compared to actual measurements using an artificial neural network (ANN), resulting in an R2=0.7449, equivalent to linear regression. The system has been successfully installed and operated on a handheld tractor and tested in Paddy Fields on the outskirts of Can Tho City, Vietnam.

Measurement of soil electrical conductivity based on direct digital synthesizer (DDS) and digital oscilloscope

A soil electrical conductivity (EC) measurement system based on direct digital synthesizer (DDS) and digital oscilloscope was developed. The system took the “current-voltage four-electrode method” as the design principal and adopted a six-pin structure of the probe, two center pins to measure the soil EC in shallow layer, two outside pins to measure the soil EC in deep layer, and two middle pins for inputting the driving current. A signal generating circuit using DDS technology was adopted to generate sine signals, which was connected with the two middle pins. A digital oscilloscope was used to record and store the two soil output signals with noises in microseconds, which were from the two center pins and two outside pins, respectively. Then a digital bandpass filter was used to filter the soil output signals recorded by the digital oscilloscope. Compared with the traditional analog filter circuit, the digital filter could filter out the noises of all frequency except for the frequency of the excitation source. It could improve the effect of filtering and the accuracy of the soil EC measurement system. The DDS circuit could provide more stable sine signals with larger amplitudes. The use of digital oscilloscope enables us to analyze the soil output signals in microseconds and measure the soil EC more accurately. The new soil EC measurement system based on DDS and digital oscilloscope can provide a new effective tool for soil sensing in precision agriculture. Keywords: soil electrical conductivity, direct digital synthesizer, digital oscilloscope, precision agriculture, current-voltage four-electrode method DOI: 10.25165/j.ijabe.20191206.4840 Citation: Pei X S, Meng C, Li M Z, Yang W, Zhou P. Measurement of soil electrical conductivity based on direct digital synthesizer (DDS) and digital oscilloscope. Int J Agric & Biol Eng, 2019; 12(6): 162–168.

Measurement of soil electrical conductivity based on direct digital synthesizer (DDS) and digital oscilloscope

A soil electrical conductivity (EC) measurement system based on direct digital synthesizer (DDS) and digital oscilloscope was developed. The system took the “current-voltage four-electrode method” as the design principal and adopted a six-pin structure of the probe, two center pins to measure the soil EC in shallow layer, two outside pins to measure the soil EC in deep layer, and two middle pins for inputting the driving current. A signal generating circuit using DDS technology was adopted to generate sine signals, which was connected with the two middle pins. A digital oscilloscope was used to record and store the two soil output signals with noises in microseconds, which were from the two center pins and two outside pins, respectively. Then a digital bandpass filter was used to filter the soil output signals recorded by the digital oscilloscope. Compared with the traditional analog filter circuit, the digital filter could filter out the noises of all frequency except for the frequency of the excitation source. It could improve the effect of filtering and the accuracy of the soil EC measurement system. The DDS circuit could provide more stable sine signals with larger amplitudes. The use of digital oscilloscope enables us to analyze the soil output signals in microseconds and measure the soil EC more accurately. The new soil EC measurement system based on DDS and digital oscilloscope can provide a new effective tool for soil sensing in precision agriculture. Keywords: soil electrical conductivity, direct digital synthesizer, digital oscilloscope, precision agriculture, current-voltage four-electrode method DOI: 10.25165/j.ijabe.20191206.4840 Citation: Pei X S, Meng C, Li M Z, Yang W, Zhou P. Measurement of soil electrical conductivity based on direct digital synthesizer (DDS) and digital oscilloscope. Int J Agric & Biol Eng, 2019; 12(6): 162–168.

Measurement of soil electrical conductivity based on direct digital synthesizer (DDS) and digital oscilloscope

A soil electrical conductivity (EC) measurement system based on direct digital synthesizer (DDS) and digital oscilloscope was developed. The system took the “current-voltage four-electrode method” as the design principal and adopted a six-pin structure of the probe, two center pins to measure the soil EC in shallow layer, two outside pins to measure the soil EC in deep layer, and two middle pins for inputting the driving current. A signal generating circuit using DDS technology was adopted to generate sine signals, which was connected with the two middle pins. A digital oscilloscope was used to record and store the two soil output signals with noises in microseconds, which were from the two center pins and two outside pins, respectively. Then a digital bandpass filter was used to filter the soil output signals recorded by the digital oscilloscope. Compared with the traditional analog filter circuit, the digital filter could filter out the noises of all frequency except for the frequency of the excitation source. It could improve the effect of filtering and the accuracy of the soil EC measurement system. The DDS circuit could provide more stable sine signals with larger amplitudes. The use of digital oscilloscope enables us to analyze the soil output signals in microseconds and measure the soil EC more accurately. The new soil EC measurement system based on DDS and digital oscilloscope can provide a new effective tool for soil sensing in precision agriculture. Keywords: soil electrical conductivity, direct digital synthesizer, digital oscilloscope, precision agriculture, current-voltage four-electrode method DOI: 10.25165/j.ijabe.20191206.4840 Citation: Pei X S, Meng C, Li M Z, Yang W, Zhou P. Measurement of soil electrical conductivity based on direct digital synthesizer (DDS) and digital oscilloscope. Int J Agric & Biol Eng, 2019; 12(6): 162–168.

Electrical Conductivity Based Quality Measurement of Diesel Exhaust Fluid

In an effort to reduce environmental pollution, the urea-selective catalytic reduction system is used to reduce NOx emissions with urea additive diesel exhaust fluid (DEF) as reductant in the exhaust of diesel engines. ISO 22241-1:2006 specifies the quality characteristics of the DEF in order to maintain efficiency, and hence it is essential that the concentration of urea in DEF is accurately monitored. In this paper an online, four-electrode, temperature compensated, electrical conductivity measurement system based on Van der Pauw theory is proposed for measuring the variation in urea concentration in DEF. The equivalent circuit model of the measurement system is developed using the Randles circuit and the equivalent circuit parameters are determined from impedance analyses of system. The prototype of the measurement cell is fabricated with all associated electronics and tested for 0.25% change in urea concentration. The experimental results are compared with results obtained from the Randles equivalent circuit model of the measurement system. The temperature effect on the measurement system is abridged from 28.75 to 2.575 mV/grad with the design of simple electronic circuit.

Negative pressure effect on the electrical conductivity of San Carlos olivine and its implication to the electrical structure in the upper mantle

Pressure effect on the electrical conductivity of San Carlos olivine was investigated by the newly installed electrical conductivity measurement system at China University of Geosciences. Electrical conductivity of San Carlos olivine aggregates was measured up to 12 GPa and 1475 K using the Walker-type multi-anvil apparatus equipped with eight WC cubes as the second-stage anvils. The pressure generation against applied load for the experimental assemblage was examined by phase transition of Bi, quartz, forsterite under different P - T conditions. To check the data validity of this new system, electrical conductivities of the serpentinites and talc samples were measured. The results are consistent with the published data of the same samples. Electrical conductivity ( σ ) of the San Carlos olivine aggregates and temperature ( T ) satisfy the Arrhenian formula: σ = σ 0 exp[−(Δ E+P Δ V)/kT ]. The pre-exponential factor ( σ 0 ), activation energy (Δ E ) and activation volume (Δ V ) yield value of 7.74 S/m, 0.85 eV and 0.94 cm 3 /mol, respectively. Electrical conductivities of the San Carlos olivine aggregates decline with increasing pressure at same temperatures. The negative pressure effect can be interpreted by strain energy model of defect energy together with the lattice deformation. In addition, the electrical conductivity-depth 1-D profile of the upper mantle was constructed based on our results and some assumptions. The calculated profile is concordant with the geophysical observation at the depth of 180–350 km beneath Europe, which indicates that the upper mantle beneath Europe might be dry.

Research of Electrical Conductivity Measurement System for Mine Bursting Water Based on Dual Frequency Method

This paper presents a double frequency conductivity measurement method for measuring mine bursting water, to solve the capacitance effect of the conductivity sensor itself has the help. The core controller of the system is the single chip microcomputer ATMEGA128. This paper introduces the basic principle of the measurement of the existing problems and the dual frequency measurement method, and then introduces and analyzes the hardware. To test and analyze the collected data, the double frequency method is found to have good stability and accuracy in the measurement of the electrical conductivity of mine inrush water. It is proved that the method and the system design of the hardware circuit can accurately measure the electric conductivity of the mine inrush water source.

Ferrite multiphase/carbon nanotube composites sintered by microwave sintering and spark plasma sintering

Ni-Carbon nanotube (CNT)-Ni0.5Zn0.5Fe2O4 multiphase composites were successfully prepared using microwave sintering (MWS) and spark plasma sintering (SPS) techniques. The obtained samples were characterized by scanning electron microscopy, electrical conductivity, and physical properties measurement system with vibrating sample magnetometer. The SPS prepared composites exhibited higher density, fine grain size, and to maintain favorable three-dimensional conductive network of CNTs compared with the microwave sintered (MWS) ones. Whether use MWS or SPS, both the density and the grain size are increasing with the CNT content increment. The increasing of density and grain size is the main contribution of the saturation magnetization increasing. In the composites of high content of CNTs (such as 5 wt %), the spinel structure of ferrite was totally destroyed, as indicated by a considerable decrease in the saturation magnetization. Interestingly, it is found that the Curie temperature increases with the increment of CNT content while the high saturation magnetization was maintained, which has implication that the multiphase ferrite composites will find application in a broad temperature range.

Embedded Based Soil Electrical Conductivity Measurement System

Electrical Conductivity measurements are often used to measure the amount of soluble salts in the soil. It is most common measure of soil salinity and is indicative of the ability of an aqueous solution to carry an electrical current. By Agricultural standards, soils with an Electrical Conductivity greater than 4 ds/m are considered for saline. In actually salt-sensitive plants may be affected by conductivities less than 4 ds/m and salt tolerant species may be impacted by concentrations of up to twice this maximum agricultural tolerant limit. Hence in the present an attempt is made to implement and embedded based soil conductivity meter.

Surface Electrical Conductivity Measurement System with Micro-Four-Point Probes at Sub-Kelvin Temperature under High Magnetic Field in Ultrahigh Vacuum

We have constructed an ultrahigh vacuum system in which surface conductivity is measured in situ by microfour-point probe method down to 0.8 K, combined with conventional surface preparation/analysis capability. In order to reduce the data scattering due to changes of the probe spacing, we have employed a dual configuration method in which the combinations with current/voltage probes are switched. The surface-state superconductivity of Si(111)- √ 7 × √ 3-In surface superstructure was confirmed with the critical temperature of 2.8 K. The critical magnetic field was 0.3-0.4 T in the surface-normal direction. [DOI: 10.1380/ejssnt.2012.400]

공업용 순알루미늄의 전기전도도에 미치는 스크랩비율 및 GBF처리조건의 영향

Effects of GBF (gas bubbling filtration) treatment conditions and scrap ratio on the electric conductivity of a commercial pure aluminum for diecasting were investigated using by specific gravity and electrical conductivity measurement system, hydrogen gas analyzer, XRD, and EDS. Electrical conductivities of specimen mixed Al scrap ratio until 60% from 0% were decreased with increasing the precipitates amount and size of AlFeSi ternary intermetallic compound on the grain boundary as well as amount of porosity in the grain. On the other hand, electrical conductivities was reincreased gradually in spite of scrap ratio increase from 80% to 100%. Size of AlFeSi compound formed on the grain boundary were coarsened with the increament of scrap ratios untill 80% and GBF treatment time simultaneously.

Pilot-scale field model tests for detecting landfill leachate intrusion into the subsurface using a grid-net electrical conductivity measurement system

The grid-net electrical conductivity measurement system for detecting exact locations of landfill leachate intrusion in the subsurface was developed in this study. Laboratory and pilot-scale field model tests were performed to evaluate the direct application of a grid-net electrical conductivity measurement system for the detection of landfill leachate. A significant increase in electrical conductivity of soil was observed by adding landfill leachate. This can be explained as an increase in electrical conductivity of pore fluid due to an increase in leachate constituents as charge carriers. In pilot-scale field model tests, leachate intrusion locations were accurately identified at the initial stage of landfill leachate release by the grid-net electrical conductivity measurement system. The electrical conductivity of the subsurface before leachate injection lay within a small range of 24.8–43.0 μS/cm. The electrical conductivity values in detected points were approximately ten times more than the conductivity values of the subsurface without landfill leachate intrusion. The results in this study indicate that the grid-net electrical conductivity measurement method has a possible application for detecting locations of landfill leachate intrusion into the subsurface at the initial stage, and thus has great potential in monitoring leachate leakage at waste landfills.

Ionic conductivity measurements of zirconia under pressure using impedancespectroscopy

We have set up an electrical conductivity measurement system underhigh-pressure and high-temperature conditions with a multi-anvil high-pressureapparatus using an AC complex impedance method. With this system, we havesuccessfully measured the electrical conductivity of stabilized ZrO2 (Y2O3–ZrO2solid solution) under pressures up to 5 GPa in the temperature range from300 to 1200 K. The electrical conductivities obtained under pressure arecompatible with those of previous results measured at ambient pressure.

Electric conductivity of olivine under pressure investigated using impedancespectroscopy

We have set up an electrical conductivity measurement system underhigh-pressure and high-temperature conditions with a multi-anvil high-pressureapparatus based on an AC complex impedance method. With this system, wehave successfully measured the electrical conductivity of San Carlos olivine underpressure up to 5 GPa. We explain the physical meaning of the activationenthalpies and activation volumes and give values for these data, which will bea great help for understanding the conduction mechanism for olivine.

Electrical Conductivity of Synthetic Quartz Crystalsat High Temperature and Pressure from Complex Impedance Measurements

An electrical conductivity measurement system under high-pressureconditions with a multi-anvil high-pressure apparatus by an ac compleximpedance method was set up. With this system, we have successfullymeasured the electrical conductivity of synthetic quartz under pressureup to approximately 1.0 GPa in the temperature range 661-987 K. The valuesof electrical conductivity decrease with the increasing pressure andincrease with the increasing temperature. The activation enthalpies forthe α-quartz crystals are 1.10-1.28 eV. The electricalconductivity of α-quartz is ionic, with Na ions moving in channelsparallel to the c-axis being the predominant current carrier.

Electrical Conductivity Measurement in Liquified Hydrogen Chloride

A measurement technology for trace impurities in hydrogen chloride was developed in relation to future ultralarge scale integration (ULSI). We developed an electrical conductivity measurement system for analyzing liquified with an in‐line high pressure cell. The detection limit of this measurement system is , and the external leak rate of the cell is below . The apparent temperature coefficient of the electrical conductivity is negative in the range from −12 to 20°C at constant pressure, which is caused by a decrease of the density of with increasing temperature. The real temperature coefficient of the electrical conductivity is positive at constant density. We observed differences in the electrical conductivity of at different lapsed times after filling and between different gas sources. An electrical conductivity of was obtained by repeated liquifaction of at a pressure of 41 kg/cm2 and 15°C.