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The electrochemical measurements investigation of NiCo2O4for electrode materials of energy storage devices by using digital holography technique
(2021-01-01)
Prakobsang, Tawipon
;
Saei, Worawee
;
Kongsubto, Thee
;
Ruttanapun, Chesta
;
Buranasiri, Prathan
The electrochemical properties of NiCo2O4for using as electrode materials for the potential applications have been investigated by electrochemical measurement which composed of cyclic voltammetry (CV) and galvanostatic chargedischarge (GCD). These processes are generating the ion exchange between the electrode and electrolyte, wherein induce the surface change of the interface. Especially, since in the cycle ability measurement using the potentiostat needed to repeat the cycle into the electrode for many times, the effective of the electrode is reduced. In this research, digital holographic technique was used to investigate the different properties of interface of the NiCo2O4 electrode while operating under the various electrochemical techniques. In our DH recording, the surface change of the electrode was expose at the difference potential scan rate at 1, 5, 10, 50, 100 and 200 mV/s of CV, and the difference current densities at 1, 2, 3, 5, 10 and 20 A/g of GCD and vary times of cycle ability test every 50 cycle times to 1000 cycles. In the end the reconstructed DH images of the electrode have been used to analyze the results from electrochemical measurement.
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Effects of Configurations of Conductor Wire in A Helix Coil Type Ozone Generator
(2018-07-02)
Leejongpermpoon, Sutee
;
Yutthagowith, Peerawut
This article presents the effects of configurations of helix-coil wire electrodes in an ozone generator with length 20cm. The effects of the configurations to the ozone production in water, i.e. air gap, wire conductor diameter, wire pitch, and turn number of wire were analyzed by using FEM simulation program. Then, to confirm the validity of the effects, various settings including setting pitch length between 0 and 40mm and the turn number of wire between 5 and 331 were performed in the simulation. Finally, the experiments are performed according to the simulation setting with the supplied voltage of 5.8 kV and the frequency of 50Hz. The results showed that the most optimized configuration has the pitch length approximately 3 times of the wire diameter.
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A development design of ozone generator with a new helix coil electrode for micro bacterial disinfection in hospitals
(2015-01-26)
Potivejkul, S.
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Leejongpermpoon, S.
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Markchun, C.
;
Kinnares, V.
This article presents development of a new helix coil electrode of an ozone generator for disinfection in hospital. In development of the proposed electrode, the optimal spacing between each turn of the helix coil has been investigated. The considered spaces are 1 cm, 2 cm, and 3 cm. To confirm the performance of the proposed electrode, the capability in ozone generation has been considered in an HV laboratory by comparison of ozone concentration generated by the proposed and conventional cylindrical electrodes. The helix coil electrode as an inner electrode was made from copper wire and the cylindrical electrode with radius of 1.5 cm as outer electrode was made of stainless steel. Those two electrodes are separated by air gap with gap spacing of 1 mm and glass material with thickness of 1.4 mm. The inner electrode is connected to a high voltage source and the outer one is connected to ground. In the experiment, air flow rate was set to be 20 l/hr to 150 l/hr. The applied peak high voltage with frequency of 20 kHz used in the experimental is set to be 0 to 6 kV. The experimental result show that the condition of the spacing of 2 cm, air flow rate of 50 l/hr and peak voltage of 6 kV provides the highest ozone concentration of 840 ppm. From the experimental results, it is high possibility that the developed electrode is able to use in ozone generators for micro bacterial disinfection in hospitals.
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Finite-element analysis of hepatic multiple probe radio-frequency ablation
(2002-07-30)
Haemmerich, Dieter
;
Tungjitkusolmun, Supan
;
Staelin, S. Tyler
;
Lee, Fred T.
;
Mahvi, David M.
Radio-frequency (RF) ablation is an important means of treatment of nonresectable primary and metastatic liver tumors. RF ablation, unlike cryoablation (a method of tumor destruction that utilizes cold rather than heat), must be performed with a single probe placed serially. The ablation of any but the smallest tumor requires the use of multiple overlapping treatment zones. We evaluated the performance of a configuration incorporating two hooked probes (RITA model 30). The probes were lined up along the same axis in parallel 20 mm apart. Three different modes applied voltage to the probes. The first mode applied energy in monopolar mode (current flows from both probes to a dispersive electrode). The second mode applied the energy to the probes in bipolar mode (current flows from one probe to the other). The third method applied the energy sequentially in monopolar mode (in 2-s intervals switched between the probes). We used the finite-element method (FEM) and analyzed the electric potential profile and the temperature distribution at the end of simulation of a 12-min ablation. The alternating monopolar mode allowed precise independent control of the amount of energy deposited at each probe. The bipolar mode created the highest temperature in the area between the probes in the configuration we examined. The monopolar mode showed the worst performance since the two probes in close vicinity create a disadvantageous electric field configuration. We, thus, conclude that alternating monopolar RF ablation is superior to the other two methods.
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Error analysis of tissue resistivity measurement
(2002-04-30)
Tsai, Jang Zern
;
Will, James A.
;
Stelle, Scott Hubbard Van
;
Cao, Hong
;
Tungjitkusolmun, Supan
We identified the error sources in a system for measuring tissue resistivity at eight frequencies from 1 Hz to 1 MHz using the four-terminal method. We expressed the measured resistivity with an analytical formula containing all error terms. We conducted practical error measurements with in-vivo and bench-top experiments. We averaged errors at all frequencies for all measurements. The standard deviations of error of the quantization error of the 8-bit digital oscilloscope with voltage averaging, the nonideality of the circuit, the in-vivo motion artifact and electrical interference combined to yield an error of ±1.19%. The dimension error in measuring the syringe tube for measuring the reference saline resistivity added ±1.32% error. The estimation of the working probe constant by interpolating a set of probe constants measured in reference saline solutions added ±0.48% error. The difference in the current magnitudes used during the probe calibration and that during the tissue resistivity measurement caused ±0.14% error. Variation of the electrode spacing, alignment, and electrode surface property due to the insertion of electrodes into the tissue caused ±0.61% error. We combined the above errors to yield an overall standard deviation error of the measured tissue resistivity of ±1.96%.
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Hepatic bipolar radio-frequency ablation between separated multiprong electrodes
(2001-10-01)
Haemmerich, Dieter
;
Staelin, S. Tyler
;
Tungjitkusolmun, Supan
;
Lee, Fred T.
;
Mahvi, David M.
Radio-frequency (RF) ablation has become an important means of treatment of nonresectable primary and metastatic liver tumors. Major limitations are small lesion size, which make multiple applications necessary, and incomplete killing of tumor cells, resulting in high recurrence rates. We examined a new bipolar RF ablation method incorporating two probes with hooked electrodes (RITA model 30). We performed monopolar and bipolar in vivo experiments on three pigs. The electrodes were 2.5 cm apart and rotated 45° relative to each other. We used temperature-controlled mode at 95 °C. Lesion volumes were 3.9 ± 1.8 cm 3 (n = 7) for the monopolar case and 12.2 ± 3 cm 3 (n = 10) for the bipolar case. We generated finite-element models (FEMs) of monopolar and bipolar configurations. We analyzed the distribution of temperature and electric field of the finite element model. The lesion volumes for the FEM are 7.95 cm 3 for the monopolar and 18.79 cm 3 for the bipolar case. The new bipolar method creates larger lesions and is less dependent on local inhomogenities in liver tissue-such as blood perfusion-compared with monopolar RF ablation. A limitation of the new method is that the power dissipation of the two probes cannot be controlled independently in response to different conditions in the vicinity of each probe. This may result in nonuniform lesions and decreased lesion size.

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