A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC...A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC) imaging is proposed to detect corrosion. The testresults show that this system has the advantage of fast scanning speed, different imaging mode andquantitative detection, it has a broad application in the aviation nondestructive testing.展开更多
Crack monitoring at the bolt hole edge is one of the important focuses of aircraft structural health monitoring.In this study,a novel eddy current sensing film based on a parallelogram coil array is developed to quant...Crack monitoring at the bolt hole edge is one of the important focuses of aircraft structural health monitoring.In this study,a novel eddy current sensing film based on a parallelogram coil array is developed to quantitatively monitor the crack characteristics near the bolt hole with fewer layers and coils,compared with the existing methods.The parallelogram coil array configuration is designed and optimized to improve the quantitative monitoring ability of the crack.A 3×3 parallelogram coil array is used to quantify the crack parameters of aluminum bolted joints.Finite element simulation and experiments show that the proposed parallelogram coil array could not only accurately and quantitatively identify the crack angle at the edge of the bolt hole,but also track the crack length along the radial direction of the bolt hole and the depth along the axial direction.展开更多
For the last several years, the linear array x-ray detector for x-ray imaging with gallium arsenide direct conversion sensitive elements has been developed and tested at the In-stitute for High Energy Physics. The arr...For the last several years, the linear array x-ray detector for x-ray imaging with gallium arsenide direct conversion sensitive elements has been developed and tested at the In-stitute for High Energy Physics. The array consists of 16 sensitive modules. Each module has 128 gallium arsenide (GaAs) sensitive elements with 200 μm pitch. Current article describes two key program procedures of initial dark current compensation of each sensitive element in the linear array, and sensitivity adjustment for alignment of strip pattern in the raw image data. As a part of evaluation process a modular transfer function (MTF) was measured with the slanted sharp-edge object under RQA5 technique as it described in the International Electrotechnical Commission 62220-1 standard (high voltage 70 kVp, additional aluminium filter 21 mm) for images with compensated dark currents and adjusted sensitivity of detector elements. The 10% level of the calculated MTF function has spatial resolution within 2 - 3 pair of lines per mm for both vertical and horizontal orientation.展开更多
In this paper,the subdomain analysis model of the eddy current brake(ECB)is established.By comparing with the finite element method,the accuracies of the subdomain model and the finite element model are verified.Furth...In this paper,the subdomain analysis model of the eddy current brake(ECB)is established.By comparing with the finite element method,the accuracies of the subdomain model and the finite element model are verified.Furthermore,the resistance characteristics of radial,axial,andHalbach arrays under impact load are calculated and compared.The axial array has a large braking force coefficient but low critical velocity.The radial array has a low braking force coefficient but high critical velocity.The Halbach array has the advantages of the first two arrays.Not only the braking force coefficient is large,but also the critical speed is high.The parameter analysis of the Halbach array is further carried out.The inner tube thickness and air gap length are the sensitive factors of resistance characteristics.The demagnetization effect is significantly enhanced by the increase of the inner tube thickness.In order to ensure that the ECB does not overheat,the electromagnetic-thermal coupling model is established based on the heat transfer theory.The temperature rise of the inner tube is obvious while that of the permanentmagnet is small.The temperature rise of the inner tube is more than 20 K each time,and that of the permanent magnet is less than 1 K each time.展开更多
A 10 × 10 solar-blind ultraviolet(UV) imaging array with double-layer wire structure was prepared based on Ga_(2)O_(3) film grown by atomic layer deposition. These single detection units in the array exhibit exce...A 10 × 10 solar-blind ultraviolet(UV) imaging array with double-layer wire structure was prepared based on Ga_(2)O_(3) film grown by atomic layer deposition. These single detection units in the array exhibit excellent performance at 3 V: photo-todark current ratio(PDCR) of 5.5 × 10^(5), responsivity(R) of 4.28 A/W, external quantum efficiency(EQE) of 2.1 × 10^(3)%, detectivity(D*) of 1.5 × 10^(14) Jones, and fast response time. The photodetector array shows high uniformity under different light intensity and low operating bias. The array also has good temperature stability. Under 300 ℃, it still presents clear imaging and keeps high R of 34.4 and 6.45 A/W at 5 and 1 V, respectively. This work provides a new insight for the large-scale array of Ga_(2)O_(3) solarblind UV detectors.展开更多
Magnetically levitated stages（MLS） have potentials to obtain good motion performances in high vacuum environment. Yet the electromagnetic forces/torques corresponding to six degrees of freedom（DOF） motions have co...Magnetically levitated stages（MLS） have potentials to obtain good motion performances in high vacuum environment. Yet the electromagnetic forces/torques corresponding to six degrees of freedom（DOF） motions have coupling relationship with each current of coil array, and this coupling is still associated with the relative positions between the mover and the stator of the stage. So it is quite difficult to control the 6-DOF motions of the stage. By reasonable commutation of coil array, this complicated coupling relationship can be decoupled. The analytical force/torque-decomposing model of the stage is established first. Then the initial currents of coil array are commutated based on the pseudo inverse of the analytical force/torque-decomposing model matrix. And then the coil array currents are commutated again with different current bounds given to the initial currents as well as in the sense of minimum 2-norm of currents vector. Using the long stroke magnetically levitated stage with moving coils under investigation as examples, the currents of coil array are commutated with different current bounds adopting the proposed commutation method, the determination of current bound and the current bounds＇ influences on the heat-losses in coil array are analyzed, and the effectiveness of implementation algorithm of proposed commutation method is discussed. Simulation, analysis and discussion results indicate that the currents of coil array within the given current bound can be solved analytically by proposed commutation method, and the implementation algorithm does not need any searching or iteration. By the current-bounded commutation method proposed, the amplitude of coil array currents can be limited within an appropriate current bound（This is very beneficial to the improvement of the reliability and motion performance of the stage）, as well as these currents can also generate the desired forces and torques.展开更多
This article presents an integrated current mode configurable analog block(CAB)system for field-programmable analog array(FPAA).The proposed architecture is based on the complementary metal-oxide semiconductor(CMOS)tr...This article presents an integrated current mode configurable analog block(CAB)system for field-programmable analog array(FPAA).The proposed architecture is based on the complementary metal-oxide semiconductor(CMOS)transistor level design where MOSFET transistors operating in the saturation region are adopted.The proposed CAB architecture is designed to implement six of thewidely used current mode operations in analog processing systems:addition,subtraction,integration,multiplication,division,and pass operation.The functionality of the proposed CAB is demonstrated through these six operations,where each operation is chosen based on the user’s selection in the CAB interface system.The architecture of the CAB system proposes an optimized way of designing and integrating only three functional cells with the interface circuitry to achieve the six operations.Furthermore,optimized programming and digital tuning circuitry are implemented in the architecture to control and interface with the functional cells.Moreover,these designed programming and tuning circuitries play an essential role in optimizing the performance of the proposed design.Simulation of the proposed CMOS Transistor Based CAB system is carried out using Tanner EDA Tools in 0.35μm standard CMOS technology.The design uses a±1.5 V power supply and results in maximum 3 dB bandwidth of 34.9 MHz and an approximate size of 0.0537 mm2.This demonstrates the advantages of the design over the current state-of-the-art designs presented for comparison in this article.Consequently,the proposed design has a clear aspect of simplicity,low power consumption,and high bandwidth operation,which makes it a suitable candidate for mobile telecommunications applications.展开更多
The design of iterative learning controller(ILC) requires to store the system input, output or control parameters of previous trials for generating the input of the current trial. In order to apply the iterative learn...The design of iterative learning controller(ILC) requires to store the system input, output or control parameters of previous trials for generating the input of the current trial. In order to apply the iterative learning controller for a real application and reduce the memory size for implementation, a current error based sampled-data proportional-derivative(PD) type iterative learning controller is proposed for control systems with initial resetting error, input disturbance and output measurement noise in this paper.The proposed iterative learning controller is simple and effective. The first contribution in this paper is to prove the learning error convergence via a rigorous technical analysis. It is shown that the learning error will converge to a residual set if a forgetting factor is introduced in the controller. All the theoretical results are also shown by computer simulations. The second main contribution is to realize the iterative learning controller by a digital circuit using a field programmable gate array(FPGA) chip applied to repetitive position tracking control of direct current(DC) motors. The feasibility and effectiveness of the proposed current error based sampleddata iterative learning controller are demonstrated by the experiment results. Finally, the relationship between learning performance and design parameters are also discussed extensively.展开更多
A hexagon pitch carbon nanotube （CNT） array vertical to the normal gate of cold cathode field emission displayer （FED） is simulated by solving the Laplace equation. The calculated results show that the normal gate...A hexagon pitch carbon nanotube （CNT） array vertical to the normal gate of cold cathode field emission displayer （FED） is simulated by solving the Laplace equation. The calculated results show that the normal gate causes the electric field around the CNT tops to be concentrated and the emission electron beam becomes a column. The field enhancement factor and the emission current intensity step up greatly compared with those of the diode structure. Emission current density increases rapidly with the decrease of normal-gate aperture. The gate voltage exerts a critical influence on the emission current.展开更多
Grid connected voltage source inverters (VSIs) are essential for the integration of the distributed energy resources. Hysteresis current control (HCC) is a commonly employed method for power control of VSIs. This cont...Grid connected voltage source inverters (VSIs) are essential for the integration of the distributed energy resources. Hysteresis current control (HCC) is a commonly employed method for power control of VSIs. This control method, in contrast with voltage control, provides good dynamics, good stability and implicit over current protection. However, the most important concern of digital implementation of HCC is related with the sampling period of the measured currents. This paper presents a predictive hysteresis current control (HCC) for grid connected voltage source inverter and its FPGA implementation. Simulation and experimental results are provided to verify the validity of the proposed implementation.展开更多
In pressurized nuclear power plants,metallic tubes such as steam generator(SG)tubes are subject to complex mechanical and environmental loads that can lead to crack initiation and propagation.Evaluating the structural...In pressurized nuclear power plants,metallic tubes such as steam generator(SG)tubes are subject to complex mechanical and environmental loads that can lead to crack initiation and propagation.Evaluating the structural integrity of SG tubes requires non-destructive assessment of crack size and location.Current inversion schemes can determine crack shape but lack position information,and reconstruction using a single coil has low efficiency.While array probes improve defect detection,reconstruction research based on array signals is challenging due to the complexity of processing multiple sets of signals.This study proposes a simple and effective array reconstruction scheme utilizing signals from two adjacent coils near the crack,enabling simultaneous determination of both crack shape and location through interpolation techniques.Numerical results validate this new crack sizing method,showing accurate reconstruction of both size and location.展开更多
The integration of numerous distributed energy resources and power electronic devices introduces a wide spectrum of frequency disturbances,which significantly challenge the stability of modern power systems.Therefore,...The integration of numerous distributed energy resources and power electronic devices introduces a wide spectrum of frequency disturbances,which significantly challenge the stability of modern power systems.Therefore,there is an urgent need to enhance the current monitoring level of modern power systems.This paper proposes a novel busbar current inversion scheme based on an elliptical magnetic sensor array.By establishing a simulation model,the effect of structural parameters of the elliptical array on its current measurement accuracy was analysed.The anti-interference capability of the elliptical array in complex environments such as busbar displacement and crosstalk was studied,and principles for designing array parameters under different current sensor standards were established.Experiments conducted on the proposed current sensing scheme demon-strated that the designed current array has a range of 0-150 A,with a current mea-surement error below 0.1% without external interference and not exceeding 1%during busbar displacement.Under conditions of crosstalk,the measurement accuracy achieved was class 0.5.The sensor array possesses high measurement accuracy,robust anti-interference capability,low power consumption,compact size and a noncontact nature.It exhibits significant potential for extensive application in novel business scenarios within the power system.展开更多
A novel fully-depleted dual-gate MOSFET with a hetero-material gate and a lightly-doped drain is proposed. The hetero-material gate, which consists of a main gate and two side-gates,is used to control the surface pote...A novel fully-depleted dual-gate MOSFET with a hetero-material gate and a lightly-doped drain is proposed. The hetero-material gate, which consists of a main gate and two side-gates,is used to control the surface potential distribution. The fabrication process and the device characteristics are simulated with Tsuprem-4 and Medici separately. Compared to a common DG fully depleted SO1 MOSFET,the proposed device has much higher on/off current ratio and superior sub-threshold slope. The on/off current ratio is about 10^10 and the sub-threshold slope is nearly 60mV/dec under a 0.18μm process.展开更多
An ultra-thin flexible eddy current proximity sensor array was developed for online measurements of tiny gaps between large smooth metallic and nonmetallic surfaces of arbitrary shapes. The probe of the flexible eddy ...An ultra-thin flexible eddy current proximity sensor array was developed for online measurements of tiny gaps between large smooth metallic and nonmetallic surfaces of arbitrary shapes. The probe of the flexible eddy current sensor array, which includes a set of sensor coils, is fabricated on a thin flexible substrate using the flexible printed circuit board process which allows the probe to be very thin and flexible so that it can conform to the surface geometry of the measured objects. The sensor coils are connected to an inductance-capacitance oscillator, which converts the distance between the sensor coil and the metallic target to a frequency output. Experimental results show that the measurement accuracy of the sensor system can reach ±0.5% for a 2-mm gap and the sensor system is suitable for online gap measurements.展开更多
Pulse width modulation （ PWM） drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array （ FPGA ）. First, digital PWM...Pulse width modulation （ PWM） drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array （ FPGA ）. First, digital PWM principles are discussed. The primary and secondary current characteristics are analyzed when the transformer is in both normal and magnetic bias conditions. Second, two digitalization methods are put forward after the research on PWM adjustment principles, which are based on the primary current feedback. Though the two methods could restrain magnetic bias, their realization is difficult. A new method is researched on double close-loops to overcome the above shortcomings, which uses the secondary current as the feedback signal and the primary current as the protection signal. Finally, the secondary current control made is discussed and realized. Welding experimental results show that the method has strong flexibility and adaptability, which can be used to realize the full digital welding power supply.展开更多
This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source--a ...This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source--a current dipole and volume currents. Then by using the simulated magnetic fields based on torso-heart model as input, the cardiac current sources--an array of current dipoles by optimal constrained linear inverse method are constructed. Next, the current dipole array reconstruction considering boundaries is compared with that in an unbounded homogeneous medium. Furthermore, the influence of random noise on reconstruction is also considered and the reconstructing effect is judged by several reconstructing parameters.展开更多
This paper proposes an equivalent circuit model to analyze the reason for the dispersion of sub-threshold current （also known as zero-current point dispersion） in organic thin-film transistors. Based on the level 61...This paper proposes an equivalent circuit model to analyze the reason for the dispersion of sub-threshold current （also known as zero-current point dispersion） in organic thin-film transistors. Based on the level 61 amorphous silicon thin-film transistor model in star-HSPICE, the results from our equivalent circuit model simulation reveal that zero-current point dispersion can be attributed to two factors： large contact resistance and small gate resistance. Furthermore, it is found that decreasing the contact resistance and increasing the gate resistance can efficiently reduce the dispersion. If the contact resistance can be controlled to 0 g2, all the zero-current points can gather together at the base point. A large gate resistance is good for constraining the dispersion of the zero-current points and gate leakage. The variances of the zero-current points are 0.0057 and nearly 0 when the gate resistances are 17 MΩ and 276 MΩ, respectively.展开更多
In Present scenario battery-powered hand-held multimedia systems become popular. The power consumption in these devices is a major concern these days for its long operational life. Although various techniques to reduc...In Present scenario battery-powered hand-held multimedia systems become popular. The power consumption in these devices is a major concern these days for its long operational life. Although various techniques to reduce the power dissipation has been developed. The most adopted method is to lower the supply voltage. But lowering the Vdd reduces the gate current much more rapidly than the sub-threshold current and degrades the SNM. This degraded SNM further limits the voltage scaling. To improve the stability of the SRAM cell topology of the conventional 6T Static Random Access Memory (SRAM) cell has been changed and revised to 8T and 10T cell, the topologies. This work has analyzed the SRAM’s Static Noise Margin (SNM) at 8T for various process corners at 65nm technology. It evaluates the SNM along with the write margins of the cell along with the cell size of 8T SRAM bit-cell operating in sub-threshold voltage at various process corners. It is observed that an 8T cell has 13 % better write margin than conventional 6T SRAM cell. This paper analyses the dependence of SNM of SRAM memory cell on supply voltage, temperature, transistor sizing in 65nm technology at various process corners (TT, SS, FF, FS, and SF).展开更多
For non-destructive optical characterization, laser beam induced current(LBIC) microscopy has been developed into as a quantitative tool to examine individual photodiodes within a large pixel array. Two-dimensional LB...For non-destructive optical characterization, laser beam induced current(LBIC) microscopy has been developed into as a quantitative tool to examine individual photodiodes within a large pixel array. Two-dimensional LBIC microscopy, also generally called photocurrent mapping(PC mapping), can provide spatially resolved information about local electrical properties and p-n junction formation in photovoltaic infrared(including visible light) photodetectors from which it is possible to extract material and device parameters such as junction area, junction depth, diffusion length, leakage current position and minority carrier diffusion length etc. This paper presents a comprehensive review of research background, operating principle, fundamental issues, and applications of LBIC or PC mapping.展开更多
A CMOS voltage reference circuit based on sub-threshold MOSFETs is proposed, which utilizes a temperature-dependent threshold voltage, a peaking current mirror and sub-threshold technology. The reference has been fabr...A CMOS voltage reference circuit based on sub-threshold MOSFETs is proposed, which utilizes a temperature-dependent threshold voltage, a peaking current mirror and sub-threshold technology. The reference has been fabricated in an SMIC 0.13 μm CMOS process with only MOS transistors and resistors. The experimental results show a reference voltage variation of 2 mV for a supply voltage ranging from 0.5 to 1.2 V and 0.8 mV for temperatures from -20 to 120 ℃C. The proposed circuit generates a reference voltage of 140 mV and consumes a supply current of 0.8 μA at room temperature. The occupied area is only 0.019 mm^2.展开更多
文摘A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC) imaging is proposed to detect corrosion. The testresults show that this system has the advantage of fast scanning speed, different imaging mode andquantitative detection, it has a broad application in the aviation nondestructive testing.
基金supported by the Natural Science Foundation of China(No.11902280)Aeronautical Science Fund(No.20200033068001)+1 种基金Innovation Fosundation for Young Scholar of Xiamen(No.3502Z20206042)the Fundamental Research Funds for the Central Universities(No.20720210049)。
文摘Crack monitoring at the bolt hole edge is one of the important focuses of aircraft structural health monitoring.In this study,a novel eddy current sensing film based on a parallelogram coil array is developed to quantitatively monitor the crack characteristics near the bolt hole with fewer layers and coils,compared with the existing methods.The parallelogram coil array configuration is designed and optimized to improve the quantitative monitoring ability of the crack.A 3×3 parallelogram coil array is used to quantify the crack parameters of aluminum bolted joints.Finite element simulation and experiments show that the proposed parallelogram coil array could not only accurately and quantitatively identify the crack angle at the edge of the bolt hole,but also track the crack length along the radial direction of the bolt hole and the depth along the axial direction.
文摘For the last several years, the linear array x-ray detector for x-ray imaging with gallium arsenide direct conversion sensitive elements has been developed and tested at the In-stitute for High Energy Physics. The array consists of 16 sensitive modules. Each module has 128 gallium arsenide (GaAs) sensitive elements with 200 μm pitch. Current article describes two key program procedures of initial dark current compensation of each sensitive element in the linear array, and sensitivity adjustment for alignment of strip pattern in the raw image data. As a part of evaluation process a modular transfer function (MTF) was measured with the slanted sharp-edge object under RQA5 technique as it described in the International Electrotechnical Commission 62220-1 standard (high voltage 70 kVp, additional aluminium filter 21 mm) for images with compensated dark currents and adjusted sensitivity of detector elements. The 10% level of the calculated MTF function has spatial resolution within 2 - 3 pair of lines per mm for both vertical and horizontal orientation.
基金supported by the National Natural Science Foundation of China(Grant No.51705253).
文摘In this paper,the subdomain analysis model of the eddy current brake(ECB)is established.By comparing with the finite element method,the accuracies of the subdomain model and the finite element model are verified.Furthermore,the resistance characteristics of radial,axial,andHalbach arrays under impact load are calculated and compared.The axial array has a large braking force coefficient but low critical velocity.The radial array has a low braking force coefficient but high critical velocity.The Halbach array has the advantages of the first two arrays.Not only the braking force coefficient is large,but also the critical speed is high.The parameter analysis of the Halbach array is further carried out.The inner tube thickness and air gap length are the sensitive factors of resistance characteristics.The demagnetization effect is significantly enhanced by the increase of the inner tube thickness.In order to ensure that the ECB does not overheat,the electromagnetic-thermal coupling model is established based on the heat transfer theory.The temperature rise of the inner tube is obvious while that of the permanentmagnet is small.The temperature rise of the inner tube is more than 20 K each time,and that of the permanent magnet is less than 1 K each time.
基金supported by Natural Science Basic Research Program of Shaanxi Province of China (No. 2023-JCYB-574)National Natural Science Foundation of China (Grant No. 62304178)。
文摘A 10 × 10 solar-blind ultraviolet(UV) imaging array with double-layer wire structure was prepared based on Ga_(2)O_(3) film grown by atomic layer deposition. These single detection units in the array exhibit excellent performance at 3 V: photo-todark current ratio(PDCR) of 5.5 × 10^(5), responsivity(R) of 4.28 A/W, external quantum efficiency(EQE) of 2.1 × 10^(3)%, detectivity(D*) of 1.5 × 10^(14) Jones, and fast response time. The photodetector array shows high uniformity under different light intensity and low operating bias. The array also has good temperature stability. Under 300 ℃, it still presents clear imaging and keeps high R of 34.4 and 6.45 A/W at 5 and 1 V, respectively. This work provides a new insight for the large-scale array of Ga_(2)O_(3) solarblind UV detectors.
基金supported by National Basic Research Program of China(973 Program, Grant No. 2009CB724205)National Hi-tech Research and Development Program of China(863 Program, Grant No. 2009AA04Z148)Independent Research Program of the State Key Laboratory of Tribology of China(Grant No. SKLT08B04)
文摘Magnetically levitated stages（MLS） have potentials to obtain good motion performances in high vacuum environment. Yet the electromagnetic forces/torques corresponding to six degrees of freedom（DOF） motions have coupling relationship with each current of coil array, and this coupling is still associated with the relative positions between the mover and the stator of the stage. So it is quite difficult to control the 6-DOF motions of the stage. By reasonable commutation of coil array, this complicated coupling relationship can be decoupled. The analytical force/torque-decomposing model of the stage is established first. Then the initial currents of coil array are commutated based on the pseudo inverse of the analytical force/torque-decomposing model matrix. And then the coil array currents are commutated again with different current bounds given to the initial currents as well as in the sense of minimum 2-norm of currents vector. Using the long stroke magnetically levitated stage with moving coils under investigation as examples, the currents of coil array are commutated with different current bounds adopting the proposed commutation method, the determination of current bound and the current bounds＇ influences on the heat-losses in coil array are analyzed, and the effectiveness of implementation algorithm of proposed commutation method is discussed. Simulation, analysis and discussion results indicate that the currents of coil array within the given current bound can be solved analytically by proposed commutation method, and the implementation algorithm does not need any searching or iteration. By the current-bounded commutation method proposed, the amplitude of coil array currents can be limited within an appropriate current bound（This is very beneficial to the improvement of the reliability and motion performance of the stage）, as well as these currents can also generate the desired forces and torques.
基金This work was supported in part by the Geran Galakan Penyelidik Muda Grant(GGPM),Universiti Kebangsaan Malaysia,Selangor,Malaysia under grant GGPM-2021-055.
文摘This article presents an integrated current mode configurable analog block(CAB)system for field-programmable analog array(FPAA).The proposed architecture is based on the complementary metal-oxide semiconductor(CMOS)transistor level design where MOSFET transistors operating in the saturation region are adopted.The proposed CAB architecture is designed to implement six of thewidely used current mode operations in analog processing systems:addition,subtraction,integration,multiplication,division,and pass operation.The functionality of the proposed CAB is demonstrated through these six operations,where each operation is chosen based on the user’s selection in the CAB interface system.The architecture of the CAB system proposes an optimized way of designing and integrating only three functional cells with the interface circuitry to achieve the six operations.Furthermore,optimized programming and digital tuning circuitry are implemented in the architecture to control and interface with the functional cells.Moreover,these designed programming and tuning circuitries play an essential role in optimizing the performance of the proposed design.Simulation of the proposed CMOS Transistor Based CAB system is carried out using Tanner EDA Tools in 0.35μm standard CMOS technology.The design uses a±1.5 V power supply and results in maximum 3 dB bandwidth of 34.9 MHz and an approximate size of 0.0537 mm2.This demonstrates the advantages of the design over the current state-of-the-art designs presented for comparison in this article.Consequently,the proposed design has a clear aspect of simplicity,low power consumption,and high bandwidth operation,which makes it a suitable candidate for mobile telecommunications applications.
基金supported by National Science Council,Taiwan,China(No.NSC102-2221-E-211-011)National Nature Science Foundation of China(No.61374102)
文摘The design of iterative learning controller(ILC) requires to store the system input, output or control parameters of previous trials for generating the input of the current trial. In order to apply the iterative learning controller for a real application and reduce the memory size for implementation, a current error based sampled-data proportional-derivative(PD) type iterative learning controller is proposed for control systems with initial resetting error, input disturbance and output measurement noise in this paper.The proposed iterative learning controller is simple and effective. The first contribution in this paper is to prove the learning error convergence via a rigorous technical analysis. It is shown that the learning error will converge to a residual set if a forgetting factor is introduced in the controller. All the theoretical results are also shown by computer simulations. The second main contribution is to realize the iterative learning controller by a digital circuit using a field programmable gate array(FPGA) chip applied to repetitive position tracking control of direct current(DC) motors. The feasibility and effectiveness of the proposed current error based sampleddata iterative learning controller are demonstrated by the experiment results. Finally, the relationship between learning performance and design parameters are also discussed extensively.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50873047)the Foundation of Gansu Provincial Education Department,China (Grant No. 0603-02)
文摘A hexagon pitch carbon nanotube （CNT） array vertical to the normal gate of cold cathode field emission displayer （FED） is simulated by solving the Laplace equation. The calculated results show that the normal gate causes the electric field around the CNT tops to be concentrated and the emission electron beam becomes a column. The field enhancement factor and the emission current intensity step up greatly compared with those of the diode structure. Emission current density increases rapidly with the decrease of normal-gate aperture. The gate voltage exerts a critical influence on the emission current.
文摘Grid connected voltage source inverters (VSIs) are essential for the integration of the distributed energy resources. Hysteresis current control (HCC) is a commonly employed method for power control of VSIs. This control method, in contrast with voltage control, provides good dynamics, good stability and implicit over current protection. However, the most important concern of digital implementation of HCC is related with the sampling period of the measured currents. This paper presents a predictive hysteresis current control (HCC) for grid connected voltage source inverter and its FPGA implementation. Simulation and experimental results are provided to verify the validity of the proposed implementation.
基金the National Key R&D Program of China(No.2023YFF0615200)the Natural Science Foundation of China(Grant No.52477015,No.U2130206,No.12222207)the General Collaborative Research Project(Project Code:J24I008)of Institute of Fluid Science,Tohoku University,Japan.
文摘In pressurized nuclear power plants,metallic tubes such as steam generator(SG)tubes are subject to complex mechanical and environmental loads that can lead to crack initiation and propagation.Evaluating the structural integrity of SG tubes requires non-destructive assessment of crack size and location.Current inversion schemes can determine crack shape but lack position information,and reconstruction using a single coil has low efficiency.While array probes improve defect detection,reconstruction research based on array signals is challenging due to the complexity of processing multiple sets of signals.This study proposes a simple and effective array reconstruction scheme utilizing signals from two adjacent coils near the crack,enabling simultaneous determination of both crack shape and location through interpolation techniques.Numerical results validate this new crack sizing method,showing accurate reconstruction of both size and location.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFB2402900Science and Technology Project of State Grid,Grant/Award Number:52060023001T。
文摘The integration of numerous distributed energy resources and power electronic devices introduces a wide spectrum of frequency disturbances,which significantly challenge the stability of modern power systems.Therefore,there is an urgent need to enhance the current monitoring level of modern power systems.This paper proposes a novel busbar current inversion scheme based on an elliptical magnetic sensor array.By establishing a simulation model,the effect of structural parameters of the elliptical array on its current measurement accuracy was analysed.The anti-interference capability of the elliptical array in complex environments such as busbar displacement and crosstalk was studied,and principles for designing array parameters under different current sensor standards were established.Experiments conducted on the proposed current sensing scheme demon-strated that the designed current array has a range of 0-150 A,with a current mea-surement error below 0.1% without external interference and not exceeding 1%during busbar displacement.Under conditions of crosstalk,the measurement accuracy achieved was class 0.5.The sensor array possesses high measurement accuracy,robust anti-interference capability,low power consumption,compact size and a noncontact nature.It exhibits significant potential for extensive application in novel business scenarios within the power system.
文摘A novel fully-depleted dual-gate MOSFET with a hetero-material gate and a lightly-doped drain is proposed. The hetero-material gate, which consists of a main gate and two side-gates,is used to control the surface potential distribution. The fabrication process and the device characteristics are simulated with Tsuprem-4 and Medici separately. Compared to a common DG fully depleted SO1 MOSFET,the proposed device has much higher on/off current ratio and superior sub-threshold slope. The on/off current ratio is about 10^10 and the sub-threshold slope is nearly 60mV/dec under a 0.18μm process.
文摘An ultra-thin flexible eddy current proximity sensor array was developed for online measurements of tiny gaps between large smooth metallic and nonmetallic surfaces of arbitrary shapes. The probe of the flexible eddy current sensor array, which includes a set of sensor coils, is fabricated on a thin flexible substrate using the flexible printed circuit board process which allows the probe to be very thin and flexible so that it can conform to the surface geometry of the measured objects. The sensor coils are connected to an inductance-capacitance oscillator, which converts the distance between the sensor coil and the metallic target to a frequency output. Experimental results show that the measurement accuracy of the sensor system can reach ±0.5% for a 2-mm gap and the sensor system is suitable for online gap measurements.
文摘Pulse width modulation （ PWM） drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array （ FPGA ）. First, digital PWM principles are discussed. The primary and secondary current characteristics are analyzed when the transformer is in both normal and magnetic bias conditions. Second, two digitalization methods are put forward after the research on PWM adjustment principles, which are based on the primary current feedback. Though the two methods could restrain magnetic bias, their realization is difficult. A new method is researched on double close-loops to overcome the above shortcomings, which uses the secondary current as the feedback signal and the primary current as the protection signal. Finally, the secondary current control made is discussed and realized. Welding experimental results show that the method has strong flexibility and adaptability, which can be used to realize the full digital welding power supply.
基金Project supported by the State Key Development Program for Basic Research of China(Grant No.2006CB601007)the National Natural Science Foundation of China(Grant No.10674006)the National High Technology Research and Development Program of China(Grant No.2007AA03Z238)
文摘This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source--a current dipole and volume currents. Then by using the simulated magnetic fields based on torso-heart model as input, the cardiac current sources--an array of current dipoles by optimal constrained linear inverse method are constructed. Next, the current dipole array reconstruction considering boundaries is compared with that in an unbounded homogeneous medium. Furthermore, the influence of random noise on reconstruction is also considered and the reconstructing effect is judged by several reconstructing parameters.
文摘This paper proposes an equivalent circuit model to analyze the reason for the dispersion of sub-threshold current （also known as zero-current point dispersion） in organic thin-film transistors. Based on the level 61 amorphous silicon thin-film transistor model in star-HSPICE, the results from our equivalent circuit model simulation reveal that zero-current point dispersion can be attributed to two factors： large contact resistance and small gate resistance. Furthermore, it is found that decreasing the contact resistance and increasing the gate resistance can efficiently reduce the dispersion. If the contact resistance can be controlled to 0 g2, all the zero-current points can gather together at the base point. A large gate resistance is good for constraining the dispersion of the zero-current points and gate leakage. The variances of the zero-current points are 0.0057 and nearly 0 when the gate resistances are 17 MΩ and 276 MΩ, respectively.
文摘In Present scenario battery-powered hand-held multimedia systems become popular. The power consumption in these devices is a major concern these days for its long operational life. Although various techniques to reduce the power dissipation has been developed. The most adopted method is to lower the supply voltage. But lowering the Vdd reduces the gate current much more rapidly than the sub-threshold current and degrades the SNM. This degraded SNM further limits the voltage scaling. To improve the stability of the SRAM cell topology of the conventional 6T Static Random Access Memory (SRAM) cell has been changed and revised to 8T and 10T cell, the topologies. This work has analyzed the SRAM’s Static Noise Margin (SNM) at 8T for various process corners at 65nm technology. It evaluates the SNM along with the write margins of the cell along with the cell size of 8T SRAM bit-cell operating in sub-threshold voltage at various process corners. It is observed that an 8T cell has 13 % better write margin than conventional 6T SRAM cell. This paper analyses the dependence of SNM of SRAM memory cell on supply voltage, temperature, transistor sizing in 65nm technology at various process corners (TT, SS, FF, FS, and SF).
基金supported by the State Key Program for Basic Research of China(Grant No.2014CB921600)the National Natural Science Foundation of China(Grant Nos.11322441 and 11274331)the Fund of Shanghai Science and Technology Foundation(Grant No.14JC1406400)
文摘For non-destructive optical characterization, laser beam induced current(LBIC) microscopy has been developed into as a quantitative tool to examine individual photodiodes within a large pixel array. Two-dimensional LBIC microscopy, also generally called photocurrent mapping(PC mapping), can provide spatially resolved information about local electrical properties and p-n junction formation in photovoltaic infrared(including visible light) photodetectors from which it is possible to extract material and device parameters such as junction area, junction depth, diffusion length, leakage current position and minority carrier diffusion length etc. This paper presents a comprehensive review of research background, operating principle, fundamental issues, and applications of LBIC or PC mapping.
文摘A CMOS voltage reference circuit based on sub-threshold MOSFETs is proposed, which utilizes a temperature-dependent threshold voltage, a peaking current mirror and sub-threshold technology. The reference has been fabricated in an SMIC 0.13 μm CMOS process with only MOS transistors and resistors. The experimental results show a reference voltage variation of 2 mV for a supply voltage ranging from 0.5 to 1.2 V and 0.8 mV for temperatures from -20 to 120 ℃C. The proposed circuit generates a reference voltage of 140 mV and consumes a supply current of 0.8 μA at room temperature. The occupied area is only 0.019 mm^2.
