Luquire et al. ' s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-l...Luquire et al. ' s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-layered structures in terms of eddy current testing voltage measurements. An experimental system for multi-layered thickness measurement was developed and several fitting models to formulate the relationships between detected impedance/voltage measurements and thickness are put forward using least square method. The determination of multi-layered thicknesses was investigated after inversing the voltage outputs of the detecting system. The best fitting and inversion models are presented.展开更多
The improvement of question soils with cement shows great technical, economic and environmental advantages. And interest in introducing electrical resistivity measurement to assess the quality of cement treated soils ...The improvement of question soils with cement shows great technical, economic and environmental advantages. And interest in introducing electrical resistivity measurement to assess the quality of cement treated soils has increased markedly recently due to its economical, non-destructive, and relatively non-invasive advantages. This work aims to quantify the effect of cement content （aw）, porosity （nt）, and curing time（T） on the electrical resistivity （p） and unconfined compression strength （UCS） of cement treated soil. A series of electrical resistivity tests and UCS tests of cement treated soil specimen after various curing periods were carried out. A modified Archie empirical law was proposed taking into account the effect of cement content and curing period on the electrical resistivity of cement treated soil. The results show that nt/（aw·T） and nt/（aw·T^1/2） ratio are appropriate parameters to assess electrical resistivity and UCS of cement treated soil, respectively. Finally, the relationship between UCS and electrical resistivity was also established.展开更多
Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equ...Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equivalent circuits. Therefore, the current interruption method is explored to measure the value of RΩ in direct methanol fuel cells (DMFC) at different temperatures and current densities. It is found that RΩ decreases as temperature increase, and decreases initially and then increases as current density increases. These results are consistent with those measured by the EIS technique. In most cases, the ohmic resistances with current interruption (R iR ) are larger than those with EIS (R EIS ), but the difference is small, in the range from –0.848% to 5.337%. The errors of R iR at high current densities are less than those of R EIS . Our results show that the R iR data are reliable and easy to obtain in the measurement of ohmic resistance in DMFC.展开更多
AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- men...AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- ment method combining electrogastrograrn （EGG） and impedance gastric motility （IGM） test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia （FD） and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients （mean age 40.9±9.7 years） and 40 healthy volun- teers （mean age 30.9±7.9 years） were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients （mean age 50.5±13.0 years） and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS： There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency （PNF） 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups （PNF 70.4：1：25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05）. The EGG rhythm of the gastritis patients returned to normal （frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 ：t： 0.19 one wk after treatment, P 〈 0.05） after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION： The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.展开更多
Li3V2（PO4）3 samples were synthesized by sol-gel route and high temperature solid-state reaction. The influence of Li3V2（PO4）3 as cathode materials for lithium-ion batteries on electrochemical performances was inve...Li3V2（PO4）3 samples were synthesized by sol-gel route and high temperature solid-state reaction. The influence of Li3V2（PO4）3 as cathode materials for lithium-ion batteries on electrochemical performances was investigated. The structure of Li3Va（PO4）3 as cathode materials for lithium-ion batteries and morphology of Li3V2（PO4）3 were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Electrochemical performances were characterized by charge/discharge and AC impedance measurements. Li3V2（PO4）3 with smaller grain size shows better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of Li3V2（PO4）3 are attributed to the refined grains and enhanced electrical conductivity. AC impedance measurements also show that the Li3V2（PO4）3 synthesized by sol-gel route exhibits significantly decreased charge-transfer resistance and shortened migration distance of lithium ions.展开更多
The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated...The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy （EIS） were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HC1 solution at 30 ℃. The inhibition mechanism was discussed in terms of Langrnuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption AGads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.展开更多
The corrosion resistance of C+Mo dual-implanted H13 steel wasstudied using multi-sweep cyclic voltammetry. The phase formation conditions for corrosion resistance and its effects were researched. The super-saturation ...The corrosion resistance of C+Mo dual-implanted H13 steel wasstudied using multi-sweep cyclic voltammetry. The phase formation conditions for corrosion resistance and its effects were researched. The super-saturation solid station solution of Mo+ and C+ atoms was formed in Mo+C dual implanted steel. Precipitate phase with nanometer size Fe2Mo, FeMo, MoC, Fe5C3 and Fe7C3 were formed in dual implanted layer. The passivation layer consisted of these nanometer phases. The corrosion resistance of the dual implanted layer was better than that of single Mo implantation. Jp of the Mo implanted sample is 0.55 times that of H13 steel. The corrosion resistance of the dual implantation was enhanced when ion dose increased. When the Mo+ ion dose was 6×1017/cm2 in the dual implantation, Jp of the dual implanted sample was only 0.11 times that in H13 steel. What is important is that pitting corrosion properties of dual implanted steel were improved obviously.展开更多
文摘Luquire et al. ' s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-layered structures in terms of eddy current testing voltage measurements. An experimental system for multi-layered thickness measurement was developed and several fitting models to formulate the relationships between detected impedance/voltage measurements and thickness are put forward using least square method. The determination of multi-layered thicknesses was investigated after inversing the voltage outputs of the detecting system. The best fitting and inversion models are presented.
基金Project(BK2011618) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(51108288) supported by the National Natural Science Foundation of China
文摘The improvement of question soils with cement shows great technical, economic and environmental advantages. And interest in introducing electrical resistivity measurement to assess the quality of cement treated soils has increased markedly recently due to its economical, non-destructive, and relatively non-invasive advantages. This work aims to quantify the effect of cement content （aw）, porosity （nt）, and curing time（T） on the electrical resistivity （p） and unconfined compression strength （UCS） of cement treated soil. A series of electrical resistivity tests and UCS tests of cement treated soil specimen after various curing periods were carried out. A modified Archie empirical law was proposed taking into account the effect of cement content and curing period on the electrical resistivity of cement treated soil. The results show that nt/（aw·T） and nt/（aw·T^1/2） ratio are appropriate parameters to assess electrical resistivity and UCS of cement treated soil, respectively. Finally, the relationship between UCS and electrical resistivity was also established.
基金Supported by the National High Technology Research and Development Program of China （2007AA05Z150） the National Natural Science Foundation of China （50911140287 50973055）
文摘Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equivalent circuits. Therefore, the current interruption method is explored to measure the value of RΩ in direct methanol fuel cells (DMFC) at different temperatures and current densities. It is found that RΩ decreases as temperature increase, and decreases initially and then increases as current density increases. These results are consistent with those measured by the EIS technique. In most cases, the ohmic resistances with current interruption (R iR ) are larger than those with EIS (R EIS ), but the difference is small, in the range from –0.848% to 5.337%. The errors of R iR at high current densities are less than those of R EIS . Our results show that the R iR data are reliable and easy to obtain in the measurement of ohmic resistance in DMFC.
基金Supported by The National Natural Science Foundation of China, No. 60471041 and 60901045
文摘AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- ment method combining electrogastrograrn （EGG） and impedance gastric motility （IGM） test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia （FD） and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients （mean age 40.9±9.7 years） and 40 healthy volun- teers （mean age 30.9±7.9 years） were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients （mean age 50.5±13.0 years） and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS： There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency （PNF） 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups （PNF 70.4：1：25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05）. The EGG rhythm of the gastritis patients returned to normal （frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 ：t： 0.19 one wk after treatment, P 〈 0.05） after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION： The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.
基金Projects(0991025,0842003-5 and 0832259) supported by Natural Science Foundation of Guangxi Province,ChinaProject supported by the Joint Graduate Innovation Talent Cultivation Base of Guangxi Province,ChinaProject(GuiJiaoRen[2007]71) supported by the Research Funds of the Guangxi Key Laboratory of Environmental Engineering,Protection and Assessment Program to Sponsor Teams for Innovation in the Construction of Talent Highlands in Guangxi Institutions of Higher Learning,China
文摘Li3V2（PO4）3 samples were synthesized by sol-gel route and high temperature solid-state reaction. The influence of Li3V2（PO4）3 as cathode materials for lithium-ion batteries on electrochemical performances was investigated. The structure of Li3Va（PO4）3 as cathode materials for lithium-ion batteries and morphology of Li3V2（PO4）3 were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Electrochemical performances were characterized by charge/discharge and AC impedance measurements. Li3V2（PO4）3 with smaller grain size shows better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of Li3V2（PO4）3 are attributed to the refined grains and enhanced electrical conductivity. AC impedance measurements also show that the Li3V2（PO4）3 synthesized by sol-gel route exhibits significantly decreased charge-transfer resistance and shortened migration distance of lithium ions.
基金Project(UKM-GUP-BTT-07-25-170) supported by Universiti Kebangsaan Malaysia
文摘The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy （EIS） were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HC1 solution at 30 ℃. The inhibition mechanism was discussed in terms of Langrnuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption AGads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59671051) 863 Project of National High Science and Technology of China.
文摘The corrosion resistance of C+Mo dual-implanted H13 steel wasstudied using multi-sweep cyclic voltammetry. The phase formation conditions for corrosion resistance and its effects were researched. The super-saturation solid station solution of Mo+ and C+ atoms was formed in Mo+C dual implanted steel. Precipitate phase with nanometer size Fe2Mo, FeMo, MoC, Fe5C3 and Fe7C3 were formed in dual implanted layer. The passivation layer consisted of these nanometer phases. The corrosion resistance of the dual implanted layer was better than that of single Mo implantation. Jp of the Mo implanted sample is 0.55 times that of H13 steel. The corrosion resistance of the dual implantation was enhanced when ion dose increased. When the Mo+ ion dose was 6×1017/cm2 in the dual implantation, Jp of the dual implanted sample was only 0.11 times that in H13 steel. What is important is that pitting corrosion properties of dual implanted steel were improved obviously.
