The reliability of the eddy current testing (ECT) in flaw detection is quantitatively evaluated by theprobability of detection (POD). Precise and efficient modeling of POD gives direction for the implement of ECTon si...The reliability of the eddy current testing (ECT) in flaw detection is quantitatively evaluated by theprobability of detection (POD). Precise and efficient modeling of POD gives direction for the implement of ECTon sites to avoid false or missing flaw detection. Traditional POD analysis focuses on single uncertain factor orsingle response signal with limited credibility in engineering. This paper considers multiple response signals andmultiple flaw parameters to perform POD. The flaw length, the flaw depth, the coil impedance, and the magneticflux density are comprehensively studied under various lift-off distances. A finite element model (FEM) of ECT isestablished and verified with experiments to obtain sufficient simulation data for discrete POD modeling. Thecontinuous POD function is then fitted based on the discrete values to show the superiority of integrating multiplefactors. A comparison with conventional POD analysis further demonstrates the higher reliability of ECT flawdetection considering multiple flaw parameters and multiple response signals, especially for small flaws.展开更多
The Chinese Proficiency Test(HSK)is a standardized test on Chinese language skills which has been widely introduced both in and outside China and has been playing an important role in the spread of Chinese learning al...The Chinese Proficiency Test(HSK)is a standardized test on Chinese language skills which has been widely introduced both in and outside China and has been playing an important role in the spread of Chinese learning all over the world.In 2003 Bulgaria hosted a beginner level HSK exam,which made it the first location to hold a Chinese language proficiency test on the Balkan Peninsula and ever since it has been very successful.The current paper provides a research on the current state of the Chinese Proficiency Test(HSK)аt the Confucius Institute in Sofia,Bulgaria,analyzes the factors related to the promotion of the Chinese Proficiency Test(HSK)and on this basis presents a few feasible recommendations to the benefit of the Chinese Proficiency Test(HSK).展开更多
Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformat...Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.展开更多
AIM:To evaluate the performance of commercially available immunochromatographic (ICT) and immunoblot tests covering the current infection marker CIM and conventional ELISA for the diagnosis of H pylori infection in ad...AIM:To evaluate the performance of commercially available immunochromatographic (ICT) and immunoblot tests covering the current infection marker CIM and conventional ELISA for the diagnosis of H pylori infection in adult dyspeptic patients. METHODS:Consecutive non-treated dyspeptic patients undergoing diagnostic endoscopy were tested for H pylori infection by culture, rapid urease test, and histology of gastric biopsy specimens. Serum from 61 H pylori infected and 21 non-infected patients were tested for anti-H pylori IgG antibodies by commercial ELISA (AccuBindTM ELISA, Monobind, USA), ICT (Assure H pylori Rapid Test, Genelabs Diagnostics, Singapore), and immunoblot (Helico Blot 2.1, Genelabs Diagnostics, Singapore) assays. ICT and immunoblot kits cover CIM among other parameters and their performance with and without CIM was evaluated separately. RESULTS:Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ELISA were 96.7%, 42.8%, 83.1%, 81.8%, and 82.9%, of ICT were 90.1%, 80.9%, 93.2%, 73.9%, and 87.8%, of ICT with CIM were 88.5%, 90.4%, 96.4%, 73.0%, and 89.0%, of immunoblot were 98.3%, 80.9%, 93.7%, 94.4%, and 93.9%, and of immunoblot with CIM were 98.3%, 90.4%, 96.7%, 95.0%, and 96.3%, respectively. CONCLUSION:Immunoblot with CIM had the best performance. ICT with CIM was found to be more specific and accurate than the conventional ELISA and may be useful for non-invasive diagnosis of H pylori infection.展开更多
Eddy current testing is a nondestructive testing method, which is used to detect discontinuities and defects in conductive materials. Using this technique, two different types of artificial defects in a railhead were ...Eddy current testing is a nondestructive testing method, which is used to detect discontinuities and defects in conductive materials. Using this technique, two different types of artificial defects in a railhead were evaluated in order to analyze the relationship between different types of defects and eddy current signals, and to obtain data on the size of the rail surface defects and crack location. The actually used rail sample was also studied. Surface cracks and defects were clearly observed as amplitude and phase changes of detected signals. This study succeeds in quantitatively analyzing and discriminating the damage types.展开更多
In the leakage current test, through the high speed data collection and digital filtering to the output voltage of the human body impedance network, leakage current test that is in accordance with many kinds of electr...In the leakage current test, through the high speed data collection and digital filtering to the output voltage of the human body impedance network, leakage current test that is in accordance with many kinds of electrical safety standards can be realized, and the frequency distribution information of the leakage current can be got as well, which can be used to much more completely evaluate the possible damage degree of the leakage current to the human body and analyze the reason for the appearance of the leakage current in the electric equipment.展开更多
New materials and manufacturing technologies require applicable non-destructive techniques for quality assurance so as to achieve better performance.This study comprehensively investigated the effect of influencing fa...New materials and manufacturing technologies require applicable non-destructive techniques for quality assurance so as to achieve better performance.This study comprehensively investigated the effect of influencing factors includ-ing excitation frequency,lift-off distance,defect depth and size,residual heat,and surface roughness on the defect EC signals of an Inconel 738LC alloy produced by selective laser melting(SLM).The experimental investigations recorded the impedance amplitude and phase angle of EC signals for each defect to explore the feasibility of detecting sub-surface defects by merely analyzing these two key indicators.Overall,this study revealed preliminary qualitative and roughly quantitative relationships between influencing factors and corresponding EC signals,which provided a prac-tical reference on how to quantitively inspect subsurface defects using eddy current testing(ECT)on SLMed parts,and also made solid progress toward on-line ECT in additive/subtractive hybrid manufacturing(ASHM)for fabricating SLMed parts with enhanced quality and better performance.展开更多
An experimental Paschen test setup has been established to analyze the quality of ITER current lead （CL） insulation and extend the research on Paschen＇s law under various conditions. Insulation problems can destroy...An experimental Paschen test setup has been established to analyze the quality of ITER current lead （CL） insulation and extend the research on Paschen＇s law under various conditions. Insulation problems can destroy a machine if a Paschen discharge is triggered by an insulation defect that is caused by faulty manufacturing, electromagnetic force, and thermal stress load with a certain degree of vacuum helium or pipe leakage. The results show that the CL insulation mock-up worked well under normal temperature and pressure. Besides, the mock-up also worked well in helium conditions and at 80 K temperature at different pressures. One area of CL insulation was severely destroyed when the 80 K test was conducted after 5 thermal cycles, resulting in Paschen discharge phenomenon. The breakdown voltage is maintained at a relatively low level under different pressure conditions; the change of breakdown voltage was mainly due to the change of pressure, and such change was in line with the Paschen law.展开更多
Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend ...Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine （TCT） for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a l/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions.展开更多
The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated vol...The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated voltage. According to the realistic conditions of test stations in China, a control device based on pre-arcing current detection and phase control is proposed in this paper. A sample of the control device made up of DSP TMS320LF2407A is fabricated, in which the CPLD MAX7064 is used to transmit signals for EMC design. It can be applied in full voltage synthetic making test at a level of 126kV/63kA. The test results show that, it is accurate to control the making phase of the applied voltage, whether the closing is demanded at voltage peak or zero.展开更多
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
CFRP （carbon fiber reinforced plastic） is used extensively in aircraft and spacecraft structures, because of its excellent mechanical properties. Ultrasonic testing, which is used as a non-destructive testing techni...CFRP （carbon fiber reinforced plastic） is used extensively in aircraft and spacecraft structures, because of its excellent mechanical properties. Ultrasonic testing, which is used as a non-destructive testing technique for CFRP, requires a contact medium. In contrast, eddy current testing does not require a contact medium, and when used for CFRP testing it has advantages not available with other techniques. CFRP is a laminate, with each layer being anisotropically conductive, and the distribution of the induced eddy current is yet to be determined. Here, to determine the eddy current distribution in the detection of flaws in cross-ply CFRP （0°/90°） by using a cross-point probe, we performed an FEM （finite element method） analysis of electromagnetic fields. We investigated the nature of the flaw signals and the differences in eddy current distributions between materials with and without flaws.展开更多
In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current t...In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current testing system of the case depth of this carburized steel was built by using ANSYS software as second development platform.展开更多
In order to research the bond properties between corroded reinforcement bars and concrete,reinforcement bars with different diameters and different types and concrete with different strength levels were treated specia...In order to research the bond properties between corroded reinforcement bars and concrete,reinforcement bars with different diameters and different types and concrete with different strength levels were treated specially with all soaking and impressed current method,and the bond properties were measured with the pull-out test.The comparative analysis of the bond properties of corroded reinforcement bars was carried out.The results showed that the types of reinforcement bars and concrete had great influence on the bond strength.The corrosion and volume expansion of reinforcement bars made concrete in tensile condition,which tended to produce cracks in parallel reinforced direction.The typical bond failure of plain reinforcement bars was pull-out,while the typical bond failure of ribbed reinforcement bars was split.The bond strength between corroded reinforcement bars and concrete increased with the increase of concrete strength.The bond strength of plain and ribbed reinforcement bars showed a decreasing trend after the first increase with the increase of the extent of corrosion.Through the test,the coefficients of the bond strength of plain and ribbed reinforcement bars were given,respectively.展开更多
This paper investigates the issue of testing Current Mode Logic (CML) gates. A three-bit parity checker is used as a case study. It is first shown that, as expected, the stuck-at fault model is not appropriate for tes...This paper investigates the issue of testing Current Mode Logic (CML) gates. A three-bit parity checker is used as a case study. It is first shown that, as expected, the stuck-at fault model is not appropriate for testing CML gates. It is then proved that switching the order in which inputs are applied to a gate will affect the minimum test set;this is not the case in conventional voltage mode gates. Both the circuit output and its inverse have to be monitored to reduce the size of the test set.展开更多
Due to the electrical anisotropy of carbon fiber reinforced polymer(CFRP),this paper presents a method to inverse the anisotropic conductivity of unidirectional CFRP laminate using eddy current testing(ECT). The relat...Due to the electrical anisotropy of carbon fiber reinforced polymer(CFRP),this paper presents a method to inverse the anisotropic conductivity of unidirectional CFRP laminate using eddy current testing(ECT). The relationship between the conductivity and probe signal of ECT is studied by means of numerical simulation. Finally,the accuracy of inversion result is improved by optimizing the initial conductivity by use of experimental data.展开更多
There are the application scope limits for single differential-mode current injection test method, so in order to carry out injection susceptibility test for two-pieces equipment interconnected with both ends of a cab...There are the application scope limits for single differential-mode current injection test method, so in order to carry out injection susceptibility test for two-pieces equipment interconnected with both ends of a cable simultaneously, a double differential-mode current in- jection test method (DDMCI) is proposed. The method adopted the equivalence source wave theorem and Baum-Liu-Tesche(BLT) equation as its theory foundation. The equivalent corresponding relation between injection voltage and radiation electric field intensity is derived, and the phase relation between the two injection voltage sources is confirmed. The results indicate that the amplitude and phase of the equivalent injection voltage source is closely related to the S parameter of directional coupling device, the transmission line length, and the source vector in BLT equation, but has nothing to do with the reflection coefficient between the two equipment pieces. Therefore, by choosing the right amplitude and phase of the double injection voltage sources, the DDMCI test is equivalent to the radiation test for two interconnected equipment of a system.展开更多
It is known that eddy current effect has a great influence on magnetic flux leakage testing(MFL).Usually,contacttype encoder wheels are used to measure MFL testing speed to evaluate the effect and further compensate t...It is known that eddy current effect has a great influence on magnetic flux leakage testing(MFL).Usually,contacttype encoder wheels are used to measure MFL testing speed to evaluate the effect and further compensate testing signals.This speed measurement method is complicated,and inevitable abrasion and occasional slippage will reduce the measurement accuracy.In order to solve this problem,based on eddy current effect due to the relative movement,a speed measurement method is proposed,which is contactless and simple.In the high-speed MFL testing,eddy current induced in the specimen will cause an obvious modification to the applied field.This modified field,which is measured by Hall sensor,can be utilized to reflect the moving speed.Firstly,the measurement principle is illustrated based on Faraday’s law.Then,dynamic finite element simulations are conducted to investigate the modified magnetic field distribution.Finally,laboratory experiments are performed to validate the feasibility of the proposed method.The results show that Bmz(r1)and Bmx(r2)have a linear relation with moving speed,which could be used as an alternative measurement parameter.展开更多
The paper addresses the first eddy current benchmark problem proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC). The problem simulates the eddy current response to the presence of an axisym...The paper addresses the first eddy current benchmark problem proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC). The problem simulates the eddy current response to the presence of an axisymmetric circumferential defect in an Inconel-600 tube. All simulations employ the axisymmetric code of the electromagnetic field simulator Finite Element Method Magnetics. For three different frequencies of excitation, it is explained how the displacement of the detecting coil inside the tube leads to a variation in the impedance of the eddy current coil. Variations of the resistive and inductive components of the impedance with distance from the defect region are used to build the impedance trajectory for each frequency of analysis.展开更多
In this paper, we conduct research on the current condition and countermeasures of private colleges and universities student physique health test under background of sunshine sports. For the further reform of basic ed...In this paper, we conduct research on the current condition and countermeasures of private colleges and universities student physique health test under background of sunshine sports. For the further reform of basic education thought and education idea, strengthen quality education, widening specialty caliber, and promote the reform of the teaching and scientific research combined, gradually establish a notice to strengthen quality education, integrating imparting knowledge, cultivating basic ability, improve quality, develop base solid foundation, wide knowledge and strong ability and high quality specialized talented person as has the characteristics of era of diversified and comprehensive compound talents training mode and our country higher professional sports curriculum framework should be organized by the teachers, teaching conditions, teaching management, assessment, teaching reform, the teaching effect on conception to form a multi-level, multi-factor curriculum system. With this guidance, we propose the enhanced student physique health test paradigm for the private colleges and universities student that will be innovative.展开更多
基金supported by the Key Research and Development Project of Zhejiang Province(Grant No.2023C01248,2023C01069)and the National Natural Science Foundation of China(Grant No.52375135,52305137).
文摘The reliability of the eddy current testing (ECT) in flaw detection is quantitatively evaluated by theprobability of detection (POD). Precise and efficient modeling of POD gives direction for the implement of ECTon sites to avoid false or missing flaw detection. Traditional POD analysis focuses on single uncertain factor orsingle response signal with limited credibility in engineering. This paper considers multiple response signals andmultiple flaw parameters to perform POD. The flaw length, the flaw depth, the coil impedance, and the magneticflux density are comprehensively studied under various lift-off distances. A finite element model (FEM) of ECT isestablished and verified with experiments to obtain sufficient simulation data for discrete POD modeling. Thecontinuous POD function is then fitted based on the discrete values to show the superiority of integrating multiplefactors. A comparison with conventional POD analysis further demonstrates the higher reliability of ECT flawdetection considering multiple flaw parameters and multiple response signals, especially for small flaws.
文摘The Chinese Proficiency Test(HSK)is a standardized test on Chinese language skills which has been widely introduced both in and outside China and has been playing an important role in the spread of Chinese learning all over the world.In 2003 Bulgaria hosted a beginner level HSK exam,which made it the first location to hold a Chinese language proficiency test on the Balkan Peninsula and ever since it has been very successful.The current paper provides a research on the current state of the Chinese Proficiency Test(HSK)аt the Confucius Institute in Sofia,Bulgaria,analyzes the factors related to the promotion of the Chinese Proficiency Test(HSK)and on this basis presents a few feasible recommendations to the benefit of the Chinese Proficiency Test(HSK).
基金supported by the Implementation Programs for Marine Renewable Energy Special Funds (GHME2012ZC02)
文摘Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.
文摘AIM:To evaluate the performance of commercially available immunochromatographic (ICT) and immunoblot tests covering the current infection marker CIM and conventional ELISA for the diagnosis of H pylori infection in adult dyspeptic patients. METHODS:Consecutive non-treated dyspeptic patients undergoing diagnostic endoscopy were tested for H pylori infection by culture, rapid urease test, and histology of gastric biopsy specimens. Serum from 61 H pylori infected and 21 non-infected patients were tested for anti-H pylori IgG antibodies by commercial ELISA (AccuBindTM ELISA, Monobind, USA), ICT (Assure H pylori Rapid Test, Genelabs Diagnostics, Singapore), and immunoblot (Helico Blot 2.1, Genelabs Diagnostics, Singapore) assays. ICT and immunoblot kits cover CIM among other parameters and their performance with and without CIM was evaluated separately. RESULTS:Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ELISA were 96.7%, 42.8%, 83.1%, 81.8%, and 82.9%, of ICT were 90.1%, 80.9%, 93.2%, 73.9%, and 87.8%, of ICT with CIM were 88.5%, 90.4%, 96.4%, 73.0%, and 89.0%, of immunoblot were 98.3%, 80.9%, 93.7%, 94.4%, and 93.9%, and of immunoblot with CIM were 98.3%, 90.4%, 96.7%, 95.0%, and 96.3%, respectively. CONCLUSION:Immunoblot with CIM had the best performance. ICT with CIM was found to be more specific and accurate than the conventional ELISA and may be useful for non-invasive diagnosis of H pylori infection.
文摘Eddy current testing is a nondestructive testing method, which is used to detect discontinuities and defects in conductive materials. Using this technique, two different types of artificial defects in a railhead were evaluated in order to analyze the relationship between different types of defects and eddy current signals, and to obtain data on the size of the rail surface defects and crack location. The actually used rail sample was also studied. Surface cracks and defects were clearly observed as amplitude and phase changes of detected signals. This study succeeds in quantitatively analyzing and discriminating the damage types.
文摘In the leakage current test, through the high speed data collection and digital filtering to the output voltage of the human body impedance network, leakage current test that is in accordance with many kinds of electrical safety standards can be realized, and the frequency distribution information of the leakage current can be got as well, which can be used to much more completely evaluate the possible damage degree of the leakage current to the human body and analyze the reason for the appearance of the leakage current in the electric equipment.
基金Supported by Basic Research Project of Science and Technology Plan of Shenzhen(Grant No.JCYJ20170817111811303).
文摘New materials and manufacturing technologies require applicable non-destructive techniques for quality assurance so as to achieve better performance.This study comprehensively investigated the effect of influencing factors includ-ing excitation frequency,lift-off distance,defect depth and size,residual heat,and surface roughness on the defect EC signals of an Inconel 738LC alloy produced by selective laser melting(SLM).The experimental investigations recorded the impedance amplitude and phase angle of EC signals for each defect to explore the feasibility of detecting sub-surface defects by merely analyzing these two key indicators.Overall,this study revealed preliminary qualitative and roughly quantitative relationships between influencing factors and corresponding EC signals,which provided a prac-tical reference on how to quantitively inspect subsurface defects using eddy current testing(ECT)on SLMed parts,and also made solid progress toward on-line ECT in additive/subtractive hybrid manufacturing(ASHM)for fabricating SLMed parts with enhanced quality and better performance.
基金supported by ITER IO, the National "973" Program of China (No. 2007ID2006)the National ITER Special Support for R&D on Science and Technology for ITER, CN Schedule Task (No. 2008GB102000)
文摘An experimental Paschen test setup has been established to analyze the quality of ITER current lead （CL） insulation and extend the research on Paschen＇s law under various conditions. Insulation problems can destroy a machine if a Paschen discharge is triggered by an insulation defect that is caused by faulty manufacturing, electromagnetic force, and thermal stress load with a certain degree of vacuum helium or pipe leakage. The results show that the CL insulation mock-up worked well under normal temperature and pressure. Besides, the mock-up also worked well in helium conditions and at 80 K temperature at different pressures. One area of CL insulation was severely destroyed when the 80 K test was conducted after 5 thermal cycles, resulting in Paschen discharge phenomenon. The breakdown voltage is maintained at a relatively low level under different pressure conditions; the change of breakdown voltage was mainly due to the change of pressure, and such change was in line with the Paschen law.
基金supported by the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51521064)the National High Technology Research and Development of China(863 Program,Grant No.2011AA050201)+2 种基金the Natural Science Foundation of Zhejiang Province(Grant No.LY14E050019)the Youth Funds of the State Key Laboratory of Fluid Power Transmission and Control SKLo FP_QN_1401the special funds of state oceanic renewable energy(Grant No.GHME2013ZB03)
文摘Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine （TCT） for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a l/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions.
文摘The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated voltage. According to the realistic conditions of test stations in China, a control device based on pre-arcing current detection and phase control is proposed in this paper. A sample of the control device made up of DSP TMS320LF2407A is fabricated, in which the CPLD MAX7064 is used to transmit signals for EMC design. It can be applied in full voltage synthetic making test at a level of 126kV/63kA. The test results show that, it is accurate to control the making phase of the applied voltage, whether the closing is demanded at voltage peak or zero.
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.
文摘CFRP （carbon fiber reinforced plastic） is used extensively in aircraft and spacecraft structures, because of its excellent mechanical properties. Ultrasonic testing, which is used as a non-destructive testing technique for CFRP, requires a contact medium. In contrast, eddy current testing does not require a contact medium, and when used for CFRP testing it has advantages not available with other techniques. CFRP is a laminate, with each layer being anisotropically conductive, and the distribution of the induced eddy current is yet to be determined. Here, to determine the eddy current distribution in the detection of flaws in cross-ply CFRP （0°/90°） by using a cross-point probe, we performed an FEM （finite element method） analysis of electromagnetic fields. We investigated the nature of the flaw signals and the differences in eddy current distributions between materials with and without flaws.
文摘In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current testing system of the case depth of this carburized steel was built by using ANSYS software as second development platform.
基金Supported by National Science and Technology Support Program(No.2012BAJ16B05)Program for Liaoning Excellent Talents in University(No.LJQ2011061)
文摘In order to research the bond properties between corroded reinforcement bars and concrete,reinforcement bars with different diameters and different types and concrete with different strength levels were treated specially with all soaking and impressed current method,and the bond properties were measured with the pull-out test.The comparative analysis of the bond properties of corroded reinforcement bars was carried out.The results showed that the types of reinforcement bars and concrete had great influence on the bond strength.The corrosion and volume expansion of reinforcement bars made concrete in tensile condition,which tended to produce cracks in parallel reinforced direction.The typical bond failure of plain reinforcement bars was pull-out,while the typical bond failure of ribbed reinforcement bars was split.The bond strength between corroded reinforcement bars and concrete increased with the increase of concrete strength.The bond strength of plain and ribbed reinforcement bars showed a decreasing trend after the first increase with the increase of the extent of corrosion.Through the test,the coefficients of the bond strength of plain and ribbed reinforcement bars were given,respectively.
文摘This paper investigates the issue of testing Current Mode Logic (CML) gates. A three-bit parity checker is used as a case study. It is first shown that, as expected, the stuck-at fault model is not appropriate for testing CML gates. It is then proved that switching the order in which inputs are applied to a gate will affect the minimum test set;this is not the case in conventional voltage mode gates. Both the circuit output and its inverse have to be monitored to reduce the size of the test set.
基金supported by the research fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(Nanjing University of Aeronautics and astronautics)(No. MCMS-I-0518K01&MCMSI-0519G02)Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the Natural Science Funding (No. 51875277)
文摘Due to the electrical anisotropy of carbon fiber reinforced polymer(CFRP),this paper presents a method to inverse the anisotropic conductivity of unidirectional CFRP laminate using eddy current testing(ECT). The relationship between the conductivity and probe signal of ECT is studied by means of numerical simulation. Finally,the accuracy of inversion result is improved by optimizing the initial conductivity by use of experimental data.
基金Project supported by Arm Pre-research Program （51333040101）, National Defense 973 Program （6131380301 ）, National Natural Science Foundation of China （61040003）.
文摘There are the application scope limits for single differential-mode current injection test method, so in order to carry out injection susceptibility test for two-pieces equipment interconnected with both ends of a cable simultaneously, a double differential-mode current in- jection test method (DDMCI) is proposed. The method adopted the equivalence source wave theorem and Baum-Liu-Tesche(BLT) equation as its theory foundation. The equivalent corresponding relation between injection voltage and radiation electric field intensity is derived, and the phase relation between the two injection voltage sources is confirmed. The results indicate that the amplitude and phase of the equivalent injection voltage source is closely related to the S parameter of directional coupling device, the transmission line length, and the source vector in BLT equation, but has nothing to do with the reflection coefficient between the two equipment pieces. Therefore, by choosing the right amplitude and phase of the double injection voltage sources, the DDMCI test is equivalent to the radiation test for two interconnected equipment of a system.
基金supported in part by the National Natural Science Foundation of China(Grant No.92060114)in part by the Sichuan Science and Technology Program(Nos.2022YFS0524 and 2022YFG0044).
文摘It is known that eddy current effect has a great influence on magnetic flux leakage testing(MFL).Usually,contacttype encoder wheels are used to measure MFL testing speed to evaluate the effect and further compensate testing signals.This speed measurement method is complicated,and inevitable abrasion and occasional slippage will reduce the measurement accuracy.In order to solve this problem,based on eddy current effect due to the relative movement,a speed measurement method is proposed,which is contactless and simple.In the high-speed MFL testing,eddy current induced in the specimen will cause an obvious modification to the applied field.This modified field,which is measured by Hall sensor,can be utilized to reflect the moving speed.Firstly,the measurement principle is illustrated based on Faraday’s law.Then,dynamic finite element simulations are conducted to investigate the modified magnetic field distribution.Finally,laboratory experiments are performed to validate the feasibility of the proposed method.The results show that Bmz(r1)and Bmx(r2)have a linear relation with moving speed,which could be used as an alternative measurement parameter.
文摘The paper addresses the first eddy current benchmark problem proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC). The problem simulates the eddy current response to the presence of an axisymmetric circumferential defect in an Inconel-600 tube. All simulations employ the axisymmetric code of the electromagnetic field simulator Finite Element Method Magnetics. For three different frequencies of excitation, it is explained how the displacement of the detecting coil inside the tube leads to a variation in the impedance of the eddy current coil. Variations of the resistive and inductive components of the impedance with distance from the defect region are used to build the impedance trajectory for each frequency of analysis.
文摘In this paper, we conduct research on the current condition and countermeasures of private colleges and universities student physique health test under background of sunshine sports. For the further reform of basic education thought and education idea, strengthen quality education, widening specialty caliber, and promote the reform of the teaching and scientific research combined, gradually establish a notice to strengthen quality education, integrating imparting knowledge, cultivating basic ability, improve quality, develop base solid foundation, wide knowledge and strong ability and high quality specialized talented person as has the characteristics of era of diversified and comprehensive compound talents training mode and our country higher professional sports curriculum framework should be organized by the teachers, teaching conditions, teaching management, assessment, teaching reform, the teaching effect on conception to form a multi-level, multi-factor curriculum system. With this guidance, we propose the enhanced student physique health test paradigm for the private colleges and universities student that will be innovative.
