Accurate water level measurement in nuclear reactors,particularly in PWRs(pressurized water reactors)and BWRs(boiling water reactors),is essential for ensuring the safety and efficiency of reactor operations.K-type HJ...Accurate water level measurement in nuclear reactors,particularly in PWRs(pressurized water reactors)and BWRs(boiling water reactors),is essential for ensuring the safety and efficiency of reactor operations.K-type HJTCs(heated junction thermocouples)are widely used for this purpose due to their ability to withstand extreme temperatures and radiation conditions.This article explores the role of HJTCs in reactor water level measurement and compares the performance of 2-wire and 3-wire connections.While the 2-wire connection is simple and cost-effective,it can introduce measurement inaccuracies due to wire resistance.In contrast,the 3-wire connection compensates for lead resistance,offering more precise and reliable measurements,particularly in long-distance applications.This paper discusses the operational considerations of these wiring configurations in the context of nuclear reactors and highlights the importance of choosing the appropriate connection type to optimize safety and measurement accuracy in PWR and BWR reactors.展开更多
The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, i...The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively.展开更多
For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To...For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.展开更多
The frequency dependence of admittance measurements （capacitance–voltage （C–V ） and conductance–voltage （G/ω–V ）） of Au/SnO2 /n-Si （MOS） capacitors was investigated by taking into account the effects of t...The frequency dependence of admittance measurements （capacitance–voltage （C–V ） and conductance–voltage （G/ω–V ）） of Au/SnO2 /n-Si （MOS） capacitors was investigated by taking into account the effects of the interface states （N ss ） and series resistance （Rs ） at room temperature. Admittance measurements were carried out in frequency and bias voltage ranges of 1 kHz–1 MHz and （ 5V）–（＋9V）, respectively. The values of N ss and R s were determined by using a conductance method and estimating from the admittance measurements of the MOS capacitors. At low frequencies, the interface states can follow the AC signal and yield excess capacitance and conductance. In addition, the parallel conductance （G p /ω） versus log（f） curves at various voltages include a peak due to the presence of interface states. It is observed that the N ss and their time constant （τ） range from 1.23 ×10 12 eV-1 ·cm-2 to 1.47 ×10 12 eV-1 ·cm-2 and from 7.29 ×10-5 s to 1.81 ×10-5s, respectively.展开更多
Sb microelectrodes were prepared by plating. The results of testing show that they have excellent stability, quick responding speed, high pH sensitivity (35～40 mV/pH) and long useful life in high temperature acidic e...Sb microelectrodes were prepared by plating. The results of testing show that they have excellent stability, quick responding speed, high pH sensitivity (35～40 mV/pH) and long useful life in high temperature acidic electroless nickel (EN) bath. By using Sb microelectrode, the pH value in EN reaction interface was measured in situ . There exists the fluctuation of pH during EN plating, and the amplitude of fluctuation tends to decrease with plating time. The largest fluctuation amplitude can reach 1～2 pH value. The in situ pH measurement provides reliable experimental results for explaining the formation of layer structure of EN deposit.展开更多
In this paper a pH microprobe technique was developed to measure in-situ the pH value at the electrode/solution interface. Iridium oxide was used as a pH sensitive material with good response behavior in the measured ...In this paper a pH microprobe technique was developed to measure in-situ the pH value at the electrode/solution interface. Iridium oxide was used as a pH sensitive material with good response behavior in the measured solutions. The experimental results indicated that the interfacial pH increased with the applied potential, first jumped to a maximum, then slowly decreased at the controlled potential during the electrodeposition process of functional ceramics.展开更多
Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has...Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has rarely been conducted in China. The current study aims to examine(1) the unidimensionality of a shortened Chinese version of PA self-efficacy scale(S-PASESC);(2) the measurement invariance of S-PASESC across gender and levels of education;(3) the latent factor mean difference between gender and levels of education;(4) the direct effects of self-efficacy on PA by different gender and education levels; and(5) the comparisons of the direct effects of self-efficacy on PA across gender and education levels.Methods: The participants were 5 th through 11 th grade public school students recruited from 7 cities located in different geographic regions of China. The final data include a total of 3003 participants(49.7% boys) who have completed the scales.Results: Confirmatory factor analysis(CFA) test supported the unidimensionality of S-PASESC. The S-PASESC is invariant across gender and 3 levels of education at both configural, full metric, and full scalar levels. Findings from latent mean comparisons showed that boys reported higher PA self-efficacy than girls. Students' perceived PA self-efficacy tend to decrease from elementary to high school. Finally, self-efficacy positively related to PA by groups of different gender and education levels and the relationship between self-efficacy and PA is stronger among middle school boys than girls.Conclusion: Findings suggest S-PASESC is a valid scale for measuring Chinese students' PA self-efficacy.展开更多
This paper propoes the water level measuring method based on the image, while the ruler used to indicate the water level is stained. The contamination of the ruler weakens or eliminates many features which are require...This paper propoes the water level measuring method based on the image, while the ruler used to indicate the water level is stained. The contamination of the ruler weakens or eliminates many features which are required for the image processing. However, the feature of the color difference between the ruler and the water surface are firmer on the environmental change compare to the other features. As the color differeaces are embossed, only the region of the ruler is limited to eliminate the noise, and the average image is produced by using several continuous frames. A histogram is then produced on the height axis of the produced intensity average image. Local peaks and local valleys are detected, and the section between the peak and valley which have the greatest change is looked for. The valley point at this very moment is used to detect the water level. The detected water level is then converted to the actual water level by using the mapping table. The proposed method is compared to the ultrasonic based method to evaluate its accuracy and efficiency on the various contaminated environments.展开更多
An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-p...An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.展开更多
The system principle and configuration of the double differential pressure method for measuring oil tank level are presented. The fundamental method and circuit of fiber optic transmission are analyzed .The accuracy a...The system principle and configuration of the double differential pressure method for measuring oil tank level are presented. The fundamental method and circuit of fiber optic transmission are analyzed .The accuracy and security of level measurement in the oil tanks have been greatly improved.展开更多
Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humi...Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humidity, and low illumination. A laser source and a camera were mounted at the top of the silo. The laser spot projected into the silo was imaged by the camera. The pinhole imaging principle allows the level to be found from the lateral shift of the spot image on the sensor. A pre-calibrated look-up table of the coal depth versus spot position was used to obtain the depth. The measurement accuracy depends on the step size used during pre-calibration. The actual application of a device designed according to these principles shows that it is easy to implement. The detection of the coal level in a silo at the low illumination level found in coal mines is demonstrated.展开更多
Deep levels in undoped semi insulating (SI) liquid encapsulated czochralski (LEC) GaAs were investigated through measuring extrinsic photocurrent spectra at 300 K. Two broad photoresponse bands M 1 and M 2 were obs...Deep levels in undoped semi insulating (SI) liquid encapsulated czochralski (LEC) GaAs were investigated through measuring extrinsic photocurrent spectra at 300 K. Two broad photoresponse bands M 1 and M 2 were observed in the range of 0.40 ～ 0.70 eV and the range from about 0.80 eV to the bandgap energy, respectively. It was shown that M 2 band is related to the photoionization of the deep defect EL2. M 1 band, which is reported for the first time, reveals several characteristic structures including five peaks at 0.46, 0.49, 0.56, 0.65 and 0.69 eV, respectively. The relative magnitudes of these peaks vary from sample to sample and are related to the thermal histories of the samples. These peaks are likely due to different deep levels.展开更多
The dependences of Fermi-level pinning on interface state densities for the metal-dielectric, ploycrystalline silicon-dielectric, and metal silicide-dielectric interfaces are investigated by calculating their effectiv...The dependences of Fermi-level pinning on interface state densities for the metal-dielectric, ploycrystalline silicon-dielectric, and metal silicide-dielectric interfaces are investigated by calculating their effective work functions and their pinning factors. The Fermi-level pinning factors and effective work functions of the metal-dielectric interface are observed to be more susceptible to the increasing interface state densities, differing significantly from that of the ploycrystalline silicon-dielectric interface and the metal silicide-dielectric interface. The calculation results indicate that metal silicide gates with high-temperature resistance and low resistivity are a more promising choice for the design of gate materials in metal-oxide semiconductor（MOS） technology.展开更多
Ordinary least squares(OLS) algorithm is widely applied in process measurement, because the sensor model used to estimate unknown parameters can be approximated through multivariate linear model. However, with few or ...Ordinary least squares(OLS) algorithm is widely applied in process measurement, because the sensor model used to estimate unknown parameters can be approximated through multivariate linear model. However, with few or noisy data or multi-collinearity, unbiased OLS leads to large variance. Biased estimators, especially ridge estimator, have been introduced to improve OLS by trading bias for variance. Ridge estimator is feasible as an estimator with smaller variance. At the same confidence level, with additive noise as the normal random variable, the less variance one estimator has, the shorter the two-sided symmetric confidence interval is. However, this finding is limited to the unbiased estimator and few studies analyze and compare the confidence levels between ridge estimator and OLS. This paper derives the matrix of ridge parameters under necessary and sufficient conditions based on which ridge estimator is superior to OLS in terms of mean squares error matrix, rather than mean squares error.Then the confidence levels between ridge estimator and OLS are compared under the condition of OLS fixed symmetric confidence interval, rather than the criteria for evaluating the validity of different unbiased estimators. We conclude that the confidence level of ridge estimator can not be directly compared with that of OLS based on the criteria available for unbiased estimators, which is verified by a simulation and a laboratory scale experiment on a single parameter measurement.展开更多
An experimental measurement of the lifetime of 3d^(9) ^(2)D_(3/2) metastable level in Mo^(15+)is reported in this work.The Mo^(15+)ions are produced and trapped in an electron beam ion trap with a magnetic field of 0....An experimental measurement of the lifetime of 3d^(9) ^(2)D_(3/2) metastable level in Mo^(15+)is reported in this work.The Mo^(15+)ions are produced and trapped in an electron beam ion trap with a magnetic field of 0.65 T.The decay photons emitted from 3d^(9) ^(2)D_(3/2) level are subsequently recorded via a cooled photomultiplier tube.Through meticulous scrutiny of potential systematic uncertainties affecting the measurement outcomes,we have determined the lifetime of Mo^(15+)3d^(9)2D_(3/2)metastable level to be 2.83(22)ms.The experimental result provides a clear distinguishment from existing calculations based on various theoretical approaches.展开更多
We have measured the deep energy level of the InP: Fe which is semi -insulator through the method of OTCS. The effect of light intensity on OTCS measurement is mainly discussed. There are electron trap of E_T =0.34 eV...We have measured the deep energy level of the InP: Fe which is semi -insulator through the method of OTCS. The effect of light intensity on OTCS measurement is mainly discussed. There are electron trap of E_T =0.34 eV and hole trap of E_T = 1.13 eV in InP: Fe under the strong light and low temperature. The location of the OTCS peak of electron trap (E_T = 0.34 eV) moves towards the direction of high temperaturer, when the light intensity was increased, E_T is different under different light intensity. It is corrected in terms of theory that the stuff ratio of the deep energy level is affected by the light intensity. The experiments show that the error is decreased greatly with the correction.展开更多
This paper describes the design and development of the timer based on liquid level measurement system in which timer 555 is used in astable mode. The capacitor charging time i. e. the ON time pulse width of the ti...This paper describes the design and development of the timer based on liquid level measurement system in which timer 555 is used in astable mode. The capacitor charging time i. e. the ON time pulse width of the timer output waveform which is measured using a digital storage oscillator （DSO）,is linearly proportional to the capacitance of a co-axial cylindrical capacitive transducer, and this capacitance once again linearly varies with the change in liquid level. Hence, we obtain a linear relationship between the liquid level and the capacitor charging time. The main advantages of this developed system are linear input-output relationship, small in size, easily portable, cost effective, and independent on the ambient temperature effect. The system can also be exploited to measure dielectric constant of liquid or solid in various process industries.展开更多
The IASB stated that in the review of the conceptual framework, if measurement uncertainty is very high, a measurement basis different from fair value may provide more appropriate information. Level 3 fair value measu...The IASB stated that in the review of the conceptual framework, if measurement uncertainty is very high, a measurement basis different from fair value may provide more appropriate information. Level 3 fair value measurements are inappropriate for areas （called ＂Level 4＂ by the author） in which models are not formulated and that have material uncertainty in measurement. The purpose of this paper is to elucidate ＂measurement uncertainty＂, which impacts ＂faithful representation＂ in fair value measurement, from the perspective of ＂verifiability＂. To do so, it will employ a conceptual examination of the limits of Level 3 fair value measurement based on IFRS 13 （Fair Value Measurement）. While taking into consideration recent discussions on reviewing conceptual framework, the author will reorganize the conceptual categories of verifiability （i.e., clarification of the ＂reasonable verifiability＂ categories） to underpin the fact that material uncertainties in measurement have obstructed constructing faithful representation. In addition, the author will discuss the problem that the dichotomy of direct and indirect found in IASB is not accurate enough to fully understand the concept of verifiability. In this context, the author will also suggest that the concept of verifiability, reorganized through ＂reasonable verifiability＂, can satisfy the requirements for constructing faithful representation.展开更多
Platforms facilitate information exchange,streamline resources,and reduce production and management costs for companies.However,some viral information may invade and steal company resources,or lead to information leak...Platforms facilitate information exchange,streamline resources,and reduce production and management costs for companies.However,some viral information may invade and steal company resources,or lead to information leakage.For this reason,this paper discusses the standards for cybersecurity protection,examines the current state of cybersecurity management and the risks faced by cloud platforms,expands the time and space for training on cloud platforms,and provides recommendations for measuring the level of cybersecurity protection within cloud platforms in order to build a solid foundation for them.展开更多
Based on the stability and inequality of texture features between coal and rock,this study used the digital image analysis technique to propose a coal–rock interface detection method.By using gray level co-occurrence...Based on the stability and inequality of texture features between coal and rock,this study used the digital image analysis technique to propose a coal–rock interface detection method.By using gray level co-occurrence matrix,twenty-two texture features were extracted from the images of coal and rock.Data dimension of the feature space reduced to four by feature selection,which was according to a separability criterion based on inter-class mean difference and within-class scatter.The experimental results show that the optimized features were effective in improving the separability of the samples and reducing the time complexity of the algorithm.In the optimized low-dimensional feature space,the coal–rock classifer was set up using the fsher discriminant method.Using the 10-fold cross-validation technique,the performance of the classifer was evaluated,and an average recognition rate of 94.12%was obtained.The results of comparative experiments show that the identifcation performance of the proposed method was superior to the texture description method based on gray histogram and gradient histogram.展开更多
文摘Accurate water level measurement in nuclear reactors,particularly in PWRs(pressurized water reactors)and BWRs(boiling water reactors),is essential for ensuring the safety and efficiency of reactor operations.K-type HJTCs(heated junction thermocouples)are widely used for this purpose due to their ability to withstand extreme temperatures and radiation conditions.This article explores the role of HJTCs in reactor water level measurement and compares the performance of 2-wire and 3-wire connections.While the 2-wire connection is simple and cost-effective,it can introduce measurement inaccuracies due to wire resistance.In contrast,the 3-wire connection compensates for lead resistance,offering more precise and reliable measurements,particularly in long-distance applications.This paper discusses the operational considerations of these wiring configurations in the context of nuclear reactors and highlights the importance of choosing the appropriate connection type to optimize safety and measurement accuracy in PWR and BWR reactors.
基金Project(51606224) supported by the National Natural Science Foundation of China
文摘The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively.
基金Supported by the Natural Science Foundation of Jiangxi Province under Grant No 20133ACB20005the Key Program of National Natural Science Foundation of China under Grant No 41330318+3 种基金the Key Program of Science and Technology Research of Ministry of Education under Grant No NRE1515the Foundation of Training Academic and Technical Leaders for Main Majors of Jiangxi Province under Grant No 20142BCB22006the Research Foundation of Education Bureau of Jiangxi Province under Grant No GJJ14501the Engineering Research Center of Nuclear Technology Application(East China Institute of Technology)Ministry of Education under Grant NoHJSJYB2016-1
文摘For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.
文摘The frequency dependence of admittance measurements （capacitance–voltage （C–V ） and conductance–voltage （G/ω–V ）） of Au/SnO2 /n-Si （MOS） capacitors was investigated by taking into account the effects of the interface states （N ss ） and series resistance （Rs ） at room temperature. Admittance measurements were carried out in frequency and bias voltage ranges of 1 kHz–1 MHz and （ 5V）–（＋9V）, respectively. The values of N ss and R s were determined by using a conductance method and estimating from the admittance measurements of the MOS capacitors. At low frequencies, the interface states can follow the AC signal and yield excess capacitance and conductance. In addition, the parallel conductance （G p /ω） versus log（f） curves at various voltages include a peak due to the presence of interface states. It is observed that the N ss and their time constant （τ） range from 1.23 ×10 12 eV-1 ·cm-2 to 1.47 ×10 12 eV-1 ·cm-2 and from 7.29 ×10-5 s to 1.81 ×10-5s, respectively.
文摘Sb microelectrodes were prepared by plating. The results of testing show that they have excellent stability, quick responding speed, high pH sensitivity (35～40 mV/pH) and long useful life in high temperature acidic electroless nickel (EN) bath. By using Sb microelectrode, the pH value in EN reaction interface was measured in situ . There exists the fluctuation of pH during EN plating, and the amplitude of fluctuation tends to decrease with plating time. The largest fluctuation amplitude can reach 1～2 pH value. The in situ pH measurement provides reliable experimental results for explaining the formation of layer structure of EN deposit.
文摘In this paper a pH microprobe technique was developed to measure in-situ the pH value at the electrode/solution interface. Iridium oxide was used as a pH sensitive material with good response behavior in the measured solutions. The experimental results indicated that the interfacial pH increased with the applied potential, first jumped to a maximum, then slowly decreased at the controlled potential during the electrodeposition process of functional ceramics.
基金supported by a grant from the National Social Science Foundation of China (No. 13CTY031)
文摘Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has rarely been conducted in China. The current study aims to examine(1) the unidimensionality of a shortened Chinese version of PA self-efficacy scale(S-PASESC);(2) the measurement invariance of S-PASESC across gender and levels of education;(3) the latent factor mean difference between gender and levels of education;(4) the direct effects of self-efficacy on PA by different gender and education levels; and(5) the comparisons of the direct effects of self-efficacy on PA across gender and education levels.Methods: The participants were 5 th through 11 th grade public school students recruited from 7 cities located in different geographic regions of China. The final data include a total of 3003 participants(49.7% boys) who have completed the scales.Results: Confirmatory factor analysis(CFA) test supported the unidimensionality of S-PASESC. The S-PASESC is invariant across gender and 3 levels of education at both configural, full metric, and full scalar levels. Findings from latent mean comparisons showed that boys reported higher PA self-efficacy than girls. Students' perceived PA self-efficacy tend to decrease from elementary to high school. Finally, self-efficacy positively related to PA by groups of different gender and education levels and the relationship between self-efficacy and PA is stronger among middle school boys than girls.Conclusion: Findings suggest S-PASESC is a valid scale for measuring Chinese students' PA self-efficacy.
基金supported by the Brain Korea 21 Project in 2010,the MKE(The Ministry of Knowledge Economy,Korea)the ITRC(Information Technology Research Center)support program(NIPA-2010-(C1090-1021-0010))
文摘This paper propoes the water level measuring method based on the image, while the ruler used to indicate the water level is stained. The contamination of the ruler weakens or eliminates many features which are required for the image processing. However, the feature of the color difference between the ruler and the water surface are firmer on the environmental change compare to the other features. As the color differeaces are embossed, only the region of the ruler is limited to eliminate the noise, and the average image is produced by using several continuous frames. A histogram is then produced on the height axis of the produced intensity average image. Local peaks and local valleys are detected, and the section between the peak and valley which have the greatest change is looked for. The valley point at this very moment is used to detect the water level. The detected water level is then converted to the actual water level by using the mapping table. The proposed method is compared to the ultrasonic based method to evaluate its accuracy and efficiency on the various contaminated environments.
基金Project(8151027501000008) supported by Guangdong Natural Science Foundation, ChinaProject(2007490511) supported by the Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, ChinaProject (2006K0006) supported by the Open Foundation of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, China
文摘An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.
文摘The system principle and configuration of the double differential pressure method for measuring oil tank level are presented. The fundamental method and circuit of fiber optic transmission are analyzed .The accuracy and security of level measurement in the oil tanks have been greatly improved.
基金supported by the National Natural Science Foun-dation of China (No. 51074169)
文摘Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humidity, and low illumination. A laser source and a camera were mounted at the top of the silo. The laser spot projected into the silo was imaged by the camera. The pinhole imaging principle allows the level to be found from the lateral shift of the spot image on the sensor. A pre-calibrated look-up table of the coal depth versus spot position was used to obtain the depth. The measurement accuracy depends on the step size used during pre-calibration. The actual application of a device designed according to these principles shows that it is easy to implement. The detection of the coal level in a silo at the low illumination level found in coal mines is demonstrated.
文摘Deep levels in undoped semi insulating (SI) liquid encapsulated czochralski (LEC) GaAs were investigated through measuring extrinsic photocurrent spectra at 300 K. Two broad photoresponse bands M 1 and M 2 were observed in the range of 0.40 ～ 0.70 eV and the range from about 0.80 eV to the bandgap energy, respectively. It was shown that M 2 band is related to the photoionization of the deep defect EL2. M 1 band, which is reported for the first time, reveals several characteristic structures including five peaks at 0.46, 0.49, 0.56, 0.65 and 0.69 eV, respectively. The relative magnitudes of these peaks vary from sample to sample and are related to the thermal histories of the samples. These peaks are likely due to different deep levels.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61376096,61327813,and 11234007)
文摘The dependences of Fermi-level pinning on interface state densities for the metal-dielectric, ploycrystalline silicon-dielectric, and metal silicide-dielectric interfaces are investigated by calculating their effective work functions and their pinning factors. The Fermi-level pinning factors and effective work functions of the metal-dielectric interface are observed to be more susceptible to the increasing interface state densities, differing significantly from that of the ploycrystalline silicon-dielectric interface and the metal silicide-dielectric interface. The calculation results indicate that metal silicide gates with high-temperature resistance and low resistivity are a more promising choice for the design of gate materials in metal-oxide semiconductor（MOS） technology.
基金Supported by the National Natural Science Foundation of China （21006127） and the National Basic Research Program of China （2012CB720500）.
文摘Ordinary least squares(OLS) algorithm is widely applied in process measurement, because the sensor model used to estimate unknown parameters can be approximated through multivariate linear model. However, with few or noisy data or multi-collinearity, unbiased OLS leads to large variance. Biased estimators, especially ridge estimator, have been introduced to improve OLS by trading bias for variance. Ridge estimator is feasible as an estimator with smaller variance. At the same confidence level, with additive noise as the normal random variable, the less variance one estimator has, the shorter the two-sided symmetric confidence interval is. However, this finding is limited to the unbiased estimator and few studies analyze and compare the confidence levels between ridge estimator and OLS. This paper derives the matrix of ridge parameters under necessary and sufficient conditions based on which ridge estimator is superior to OLS in terms of mean squares error matrix, rather than mean squares error.Then the confidence levels between ridge estimator and OLS are compared under the condition of OLS fixed symmetric confidence interval, rather than the criteria for evaluating the validity of different unbiased estimators. We conclude that the confidence level of ridge estimator can not be directly compared with that of OLS based on the criteria available for unbiased estimators, which is verified by a simulation and a laboratory scale experiment on a single parameter measurement.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFA1602500)the National Natural Science Foundation of China(Grant No.12274352)。
文摘An experimental measurement of the lifetime of 3d^(9) ^(2)D_(3/2) metastable level in Mo^(15+)is reported in this work.The Mo^(15+)ions are produced and trapped in an electron beam ion trap with a magnetic field of 0.65 T.The decay photons emitted from 3d^(9) ^(2)D_(3/2) level are subsequently recorded via a cooled photomultiplier tube.Through meticulous scrutiny of potential systematic uncertainties affecting the measurement outcomes,we have determined the lifetime of Mo^(15+)3d^(9)2D_(3/2)metastable level to be 2.83(22)ms.The experimental result provides a clear distinguishment from existing calculations based on various theoretical approaches.
文摘We have measured the deep energy level of the InP: Fe which is semi -insulator through the method of OTCS. The effect of light intensity on OTCS measurement is mainly discussed. There are electron trap of E_T =0.34 eV and hole trap of E_T = 1.13 eV in InP: Fe under the strong light and low temperature. The location of the OTCS peak of electron trap (E_T = 0.34 eV) moves towards the direction of high temperaturer, when the light intensity was increased, E_T is different under different light intensity. It is corrected in terms of theory that the stuff ratio of the deep energy level is affected by the light intensity. The experiments show that the error is decreased greatly with the correction.
文摘This paper describes the design and development of the timer based on liquid level measurement system in which timer 555 is used in astable mode. The capacitor charging time i. e. the ON time pulse width of the timer output waveform which is measured using a digital storage oscillator （DSO）,is linearly proportional to the capacitance of a co-axial cylindrical capacitive transducer, and this capacitance once again linearly varies with the change in liquid level. Hence, we obtain a linear relationship between the liquid level and the capacitor charging time. The main advantages of this developed system are linear input-output relationship, small in size, easily portable, cost effective, and independent on the ambient temperature effect. The system can also be exploited to measure dielectric constant of liquid or solid in various process industries.
文摘The IASB stated that in the review of the conceptual framework, if measurement uncertainty is very high, a measurement basis different from fair value may provide more appropriate information. Level 3 fair value measurements are inappropriate for areas （called ＂Level 4＂ by the author） in which models are not formulated and that have material uncertainty in measurement. The purpose of this paper is to elucidate ＂measurement uncertainty＂, which impacts ＂faithful representation＂ in fair value measurement, from the perspective of ＂verifiability＂. To do so, it will employ a conceptual examination of the limits of Level 3 fair value measurement based on IFRS 13 （Fair Value Measurement）. While taking into consideration recent discussions on reviewing conceptual framework, the author will reorganize the conceptual categories of verifiability （i.e., clarification of the ＂reasonable verifiability＂ categories） to underpin the fact that material uncertainties in measurement have obstructed constructing faithful representation. In addition, the author will discuss the problem that the dichotomy of direct and indirect found in IASB is not accurate enough to fully understand the concept of verifiability. In this context, the author will also suggest that the concept of verifiability, reorganized through ＂reasonable verifiability＂, can satisfy the requirements for constructing faithful representation.
文摘Platforms facilitate information exchange,streamline resources,and reduce production and management costs for companies.However,some viral information may invade and steal company resources,or lead to information leakage.For this reason,this paper discusses the standards for cybersecurity protection,examines the current state of cybersecurity management and the risks faced by cloud platforms,expands the time and space for training on cloud platforms,and provides recommendations for measuring the level of cybersecurity protection within cloud platforms in order to build a solid foundation for them.
基金the National Natural Science Foundation of China(No.51134024/E0422)for the financial support
文摘Based on the stability and inequality of texture features between coal and rock,this study used the digital image analysis technique to propose a coal–rock interface detection method.By using gray level co-occurrence matrix,twenty-two texture features were extracted from the images of coal and rock.Data dimension of the feature space reduced to four by feature selection,which was according to a separability criterion based on inter-class mean difference and within-class scatter.The experimental results show that the optimized features were effective in improving the separability of the samples and reducing the time complexity of the algorithm.In the optimized low-dimensional feature space,the coal–rock classifer was set up using the fsher discriminant method.Using the 10-fold cross-validation technique,the performance of the classifer was evaluated,and an average recognition rate of 94.12%was obtained.The results of comparative experiments show that the identifcation performance of the proposed method was superior to the texture description method based on gray histogram and gradient histogram.
