Stability and reliability of distribution system are able to be improved by many protective devices including insulators, relay and surge arrester (SA). SA is used for protection of lightning and switching surge in Pr...Stability and reliability of distribution system are able to be improved by many protective devices including insulators, relay and surge arrester (SA). SA is used for protection of lightning and switching surge in Provincial Electricity Au-thority (PEA). This paper presents an experimental investigation of 22 kV distribution SA electrical performances under pollution conditions according to IEC 60507. The experimental results of leakage currents more than 6 mA at Equiva-lent Salt Deposit Density (ESDD) 0.6 mg/cm2 at nominal voltage. These data will be useful to be guideline for solving problems and reducing power loss from leakage current on the surface of SAs as a result of surface dirt and pollution. Moreover, it will be useful to select or design suitable SAs for using in places with salt conditions, high rainfall, high wind speeds and high humidity.展开更多
In this paper a new active RFID system at 2.45 GHz based on the low-power system-on-chip CC2530 RF transceiver is designed and implemented. Only by using of an integrated multi-channel fast chip, both the MCU and RF o...In this paper a new active RFID system at 2.45 GHz based on the low-power system-on-chip CC2530 RF transceiver is designed and implemented. Only by using of an integrated multi-channel fast chip, both the MCU and RF operations are done which makes the RFID more reliable and reduces the complexity of the hardware and cost, vividly. This RFID system utilizes the Zig-Bee IEEE 802.15.4 standard in the ISM band. A lot amount of energy is restored by setting Tags in the sleep mode in the most of times. The maximum transmission range of 80 m at the output power of 4.5 dBm is obtained. The main application of this system is for the container identification with precise operation and high accuracy. An active Tag with unique ID is mounted on each vehicle. By enabling the AUTOCRC error detection possibility, minor errors are detected in the received frames. Receiver sensitivity of –97 dBm and current consumption of 1 μA in the sleep mode and 29.6 mA in the active mode are reported.展开更多
Variable estimation for finishing mill set-up in hot rolling is greatly affected by measurement uncertainties, variations in the incoming bar conditions and product changes. The fuzzy C-means algorithm was evaluated f...Variable estimation for finishing mill set-up in hot rolling is greatly affected by measurement uncertainties, variations in the incoming bar conditions and product changes. The fuzzy C-means algorithm was evaluated for rule base generation for fuzzy and fuzzy grey-box temperature estimation. Experimental data were collected from a real- life mill and three different sets were randomly drawn. The first set was used for rule-generation, the second set was used for training those systems with learning capabilities, while the third one was used for validation. The perform- ance of the developed systems was evaluated by five performance measures applied over the prediction error with the validation set and was compared with that of the empirical rule-base fuzzy systems and the physical model used in plant. The results show that the fuzzy C-means generated rule-bases improve temperature estimation; however, the best results are obtained when fuzzy C-means algorithm, grey-box modeling and learning functions are combined. Application of fuzzy C-means rule generation brings improvement on performance of up to 72%.展开更多
Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pande...Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.展开更多
In this study,the authors have shown the power conversion efficiency of flexible organic solar cells.The structure of the device is PET/ITO/PEDOT:PSS/P3HT:PCBM/AI.P3HT(poly-3-hexylthiophene).It was used as an electron...In this study,the authors have shown the power conversion efficiency of flexible organic solar cells.The structure of the device is PET/ITO/PEDOT:PSS/P3HT:PCBM/AI.P3HT(poly-3-hexylthiophene).It was used as an electron donor,PCBM([6,6]-phenyl C6 l-butyric acid methyl ester)as an electron acceptor and PEDOT:PSS used as a HIL(hole injection layer).These materials were deposited by spin coating method on the flexible substrates.Photolithography method is used to etch ITO.The electrical parameters of the fabricated cells were investigated by means of J(V),FF(fill factor),the efficiency(r/),photocurrent and IPCE measurement.It was observed that 45%of the absorbed photons are converted into current.The results obtained using etching technology by photolithography is better than that obtained in the clean room.展开更多
In this work, a new numerical technique is proposed for the resolution of a fluid model based on three Boltzmann moments. The main purpose of this technique is to calculate electric and physical properties in the non-...In this work, a new numerical technique is proposed for the resolution of a fluid model based on three Boltzmann moments. The main purpose of this technique is to calculate electric and physical properties in the non-equilibrium electric discharge at low pressure. The transport and Poisson＇s equations form a self-consistent model. This equation system is written in cylindrical coordinates following the geometric shape of a plasma reactor. Our transport equation system is discretized using the finite volume approach and resolved by the N-BEE explicit scheme coupled to the time splitting method. This programming structure reduces computation time considerably. The 2D code is carried out and tested by comparing our results with those found in literature.展开更多
Electric vehicles(EVs)have received special consideration from modern society over the past several years.Although EVs are a fine example of environmentally friendly technology and have many advantages,they relatively...Electric vehicles(EVs)have received special consideration from modern society over the past several years.Although EVs are a fine example of environmentally friendly technology and have many advantages,they relatively increase the electricity demand upon a power grid as well.Therefore,their negative impact on busvoltage and line losses should be analyzed.In this study,the effect of EV loads and their penetration on bus voltage and line losses of an IEEE-33 bussystem has been examined via two scenarios.It is important to mention that the effect of EVs on the rate of air pollution,produced by fossil fuel electricity generators,has been investigated throughout the study.Also,the key role of demand response programs in the reduction of EVs’negative effects on the grid has also been discussed in the last scenario.Generally,the simulation of this paper provides a novel and wider perspective on EVs and their effect on grids and environmental pollution.展开更多
Single-carrier frequency-division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA) systems are new orthogonal multiple access systems. They have been adopted in the 3GPP long term ev...Single-carrier frequency-division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA) systems are new orthogonal multiple access systems. They have been adopted in the 3GPP long term evolution (3GPP-LTE). In these systems, there are only two types of subcarrier mapping schemes which are the interleaved and the localized. So, introducing a new subcarrier mapping scheme is an important issue, which is the main objective of this paper. In this paper, a hybrid subcarrier mapping scheme is proposed and examined for the SC-FDMA system. Monte Carlo simulations are performed to compare the performance of the proposed scheme with that of the interleaved and the localized schemes. It is shown that a hybrid scheme provides better performance than that of the localized and the same performance as that of the interleaved scheme and increased robustness to carrier frequency offset (CFO) at the expense of increased envelope fluctuations.展开更多
We synthesized Zn0.8Fe2.2O4 ferrite powders by coprecipitation and hydrothermal techniques and analyzed the mor-phology and magnetic properties. The morphology and structure of the Zn ferrite powders were investigated...We synthesized Zn0.8Fe2.2O4 ferrite powders by coprecipitation and hydrothermal techniques and analyzed the mor-phology and magnetic properties. The morphology and structure of the Zn ferrite powders were investigated using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) identifying the crystallization planes. Magnetic hysteresis curves were obtained for the Zn ferrites samples.展开更多
The detection of physiological signals from the motor system （electromyographic signals） is being utilized in the practice clinic to guide the therapist in a more precise and accurate diagnosis of motor disorders. I...The detection of physiological signals from the motor system （electromyographic signals） is being utilized in the practice clinic to guide the therapist in a more precise and accurate diagnosis of motor disorders. In this context, the process of decomposition of EMG （electromyographic） signals that includes the identification and classification of MUAP （Motor Unit Action Potential） of a EMG signal, is very important to help the therapist in the evaluation of motor disorders. The EMG decomposition is a complex task due to EMG features depend on the electrode type （needle or surface）, its placement related to the muscle, the contraction level and the health of the Neuromuscular System. To date, the majority of researches on EMG decomposition utilize EMG signals acquired by needle electrodes, due to their advantages in processing this type of signal. However, relatively few researches have been conducted using surface EMG signals. Thus, this article aims to contribute to the clinical practice by presenting a technique that permit the decomposition of surface EMG signal via the use of Hidden Markov Models. This process is supported by the use of differential evolution and spectral clustering techniques. The developed system presented coherent results in： （1） identification of the number of Motor Units actives in the EMG signal; （2） presentation of the morphological patterns of MUAPs in the EMG signal; （3） identification of the firing sequence of the Motor Units. The model proposed in this work is an advance in the research area of decomposition of surface EMG signals.展开更多
Nowadays Quantum Cellular Automata (QCA) as the leading technology in design of microelectronic systems has been raised. With respect to high velocity and density in low power and also simple concepts, this technology...Nowadays Quantum Cellular Automata (QCA) as the leading technology in design of microelectronic systems has been raised. With respect to high velocity and density in low power and also simple concepts, this technology is a viable alternative to CMOS technology. In collector design, the primary component of each processor is very important. Due to the small elements in this technology, failure rate in manufacturing process technology is very high. In the other hand, the simulation shows that the intersection point of two wires is one of the critical points in QCA circuits. This means that defects in the manufacturing process around these points can cause malfunction in the circuit performance. In this paper, a collector in cross sections of wire in his new method used higher reliability against defects during manufacturing has been developed. QCA Designer software is used to simulate the case study system.展开更多
On the basis of transplanting successfully a suit of RTOSμC/OS-Ⅱto MB90F543 MCU,douhle CAN communicating program module have heen embedded intoμC/OS-Ⅱas a building block.Douhle CAN redundant communication have bee...On the basis of transplanting successfully a suit of RTOSμC/OS-Ⅱto MB90F543 MCU,douhle CAN communicating program module have heen embedded intoμC/OS-Ⅱas a building block.Douhle CAN redundant communication have been realized among several hardware nodes based onμC/OS-Ⅱ.The design mechanism,hardware and softy,are of double CAN communication were described in detail.The paper analyze the differences of CAN communication based onμC/OS-Ⅱand traditional foreground/background system.展开更多
When the authors research on the fact that some SVC （static var compensator） substations connected at some buses in power system, they realized that some main functions ensured to operate well. Those are： compensat...When the authors research on the fact that some SVC （static var compensator） substations connected at some buses in power system, they realized that some main functions ensured to operate well. Those are： compensate reactive power following value U＊ according to the requirements of the Vietnamese power system dispath center, flit harmonic by passive filter... However, it still has some disadvantages of this substation that need to be overcome： use large number of main devices, generate harmonics by itself, cause a lot of active power losses. Thus, the authors have an idea to solve these problems by applying a bidirectional power converter with having difference circuit structure and PWM （pulse width modulation） controller with SVM （space vector modulation） pulse generated section, so compensative current which is created by inductance element can be reserved, adjust continuos and always has full sinusoidal form, not generating harmonic. The benefit of this new solution is to eliminate the three above fundamental disadvantages. This new model is built based on authors＇ research about BESS （battery energy storage system）. The research results have been verified by simulations in Matlab/Simulink software.展开更多
The results of searching of equivalent for electromagnetic transient calculation in power system with the big number of transmission lines are shown. Brief information on the proper transmission line model is given. C...The results of searching of equivalent for electromagnetic transient calculation in power system with the big number of transmission lines are shown. Brief information on the proper transmission line model is given. Comparison of results of simulation in real and reduced system is presented taking into consideration three methods of identification. Some example are examined for different number of transmission lines in reduced system and consequently the recommendation are given for searching of equivalents of systems with many lines.展开更多
Dissolved gas analysis is the most widely used diagnostic test in power transformers. The aim of this paper is to introduce the dissolved gas analysis (DGA) methods able to diagnose the transformer conditions. The fau...Dissolved gas analysis is the most widely used diagnostic test in power transformers. The aim of this paper is to introduce the dissolved gas analysis (DGA) methods able to diagnose the transformer conditions. The faults cause the transformer oil, pressboard, and other insulating materials to decompose and generate gases, some of which dissolve in the oil. The results of DGA must be accurate if faults are to be diagnosed reliably. There are different established methods used in industry for interpreting DGA results. We will compare the result of IEEE Key Gas Methods and Rogers’ Ratios. The transformer conditions are evaluated by the Key Gas Method with total combustible gas method (TCGM) and then verified by the Rogers’ Ratios. As result, the aging pattern and trend of the power transformer deterioration can be determined. The 30 sample data from IEEE with known faults and dissolved gas concentrations were used as the basis of comparison.展开更多
Nowadays IPP＇s power plant construction is encouraged by the current deregulatory climate. The financing technique employed to implement these projects is often the project financing formula. Under such condition an ...Nowadays IPP＇s power plant construction is encouraged by the current deregulatory climate. The financing technique employed to implement these projects is often the project financing formula. Under such condition an investor consortium, usually foreigner plan, build, operate the power plant and sell the generated electricity to the host utility. The sale price is determined from the expected IPP＇s production cost, enhanced from the expected welfare obtainable by selling electricity. This paper proposes a methodology for linking the uncertainty of the future production cost with the price of the electricity generated by an IPP. This is a stochastic approach to the sale price definition problem, while usually conducted through a deterministic procedure.展开更多
ZnO thin films were deposited using the simple, flexible and cost-effective spray ultrasonic technique at different precursor molarities values. The films were deposited on a glass substrate at 350℃. This paper is to...ZnO thin films were deposited using the simple, flexible and cost-effective spray ultrasonic technique at different precursor molarities values. The films were deposited on a glass substrate at 350℃. This paper is to present a new approach to the description of correlation between electrical conductivity and optical gap energy with precursor molarity of ZnO thin films. The ZnO films exhibit higher electrical n-type semiconductors, whose band gap energy increased from 3.08 to 3.37 eV with an increasing of precursor molarity of 0.05 to 0.1 M. The maximum value of electrical conductivity of the films is 7.96 （S2.cm）-1 obtained in the ZnO thin film for precursor molarity 0.125 M. The correlation between the electrical and the optical properties with the precursor molarity suggests that the electrical conductivity of the films is predominantly influenced by the band gap energy and the precursor molarity. The measurement of the electrical conductivity of the films with correlation is equal to the experimental with the error is about 1% in the higher conductivity.展开更多
This paper demonstrates the application of optimization techniques,namely the Dung Beetle Optimizer(DBO)and the Ant-Lion Optimizer(ALO),to enhance the performance of cascaded Proportional Integral Derivative(PID)and F...This paper demonstrates the application of optimization techniques,namely the Dung Beetle Optimizer(DBO)and the Ant-Lion Optimizer(ALO),to enhance the performance of cascaded Proportional Integral Derivative(PID)and Fractional Order PID(FOPID)controllers at the edge of an industrial network for Switched Reluctance Motor(SRM)speed control and torque ripple reduction.These techniques present notable advantages in terms of faster convergence and reduced computational complexity compared to existing optimization methods.Our research employs PID and FOPID controllers to regulate the speed and torque of the SRM,with a comparative analysis of other optimization approaches.In the domain of SRM control,we highlight the significance of the hysteresis band block in mitigating sudden state transitions,especially crucial for ensuring stable operation in the presence of noisy or slightly variable input signals requiring precise control.The results underscore the superior performance of the proposed optimization strategies,particularly showcasing the DBO-based cascaded PID and FOPID controllers,which exhibit reduced torque and current ripples along with improved speed response.Our investigation encompasses diverse loading conditions and is substantiated through time-domain simulations performed using MATLAB/SIMULINK.展开更多
In this paper, a content based descriptor is pro- posed to retrieve 3D models, which employs histogram of local orientation （HLO） as a geometric property of the shape. The proposed 3D model descriptor scheme consist...In this paper, a content based descriptor is pro- posed to retrieve 3D models, which employs histogram of local orientation （HLO） as a geometric property of the shape. The proposed 3D model descriptor scheme consists of three steps. In the first step, Poisson equation is utilized to define a 3D model signature. Next, the local orientation is calculated for each voxel of the model using Hessian matrix. As the final step, a histogram-based 3D model descriptor is extracted by accumulating the values of the local orientation in bins. Due to efficiency of Poisson equation in describing the models with various structures, the proposed descriptor is capable of discriminating these models accurately. Since, the inner vox- els have a dominant contribution in the formation of the de- scriptor, sufficient robustness against noise can be achieved. This is because the noise mostly influences the boundary vox- els. Furthermore, we improve the retrieval performance us- ing support vector machine based one-shot score （SVM-OSS） similarity measure, which is more efficient than the conven- tional methods to compute the distance of feature vectors. The rotation normalization is performed employing the prin- cipal component analysis. To demonstrate the applicability of HLO, we implement experimental evaluations of precision- recall curve on ESB, PSB and WM-SHREC databases of 3D models. Experimental results validate the effectiveness of the proposed descriptor compared to some current methods.展开更多
In this paper,a modified sinusoidal pulse width modulation(MSPWM)technique and a modified single-phase H-bridge seven-level inverter is proposed.The switching pulses for the proposed seven-level inverter are generated...In this paper,a modified sinusoidal pulse width modulation(MSPWM)technique and a modified single-phase H-bridge seven-level inverter is proposed.The switching pulses for the proposed seven-level inverter are generated using a single triangular carrier waveform,a fully rectified sinusoidal signal,and three stepped reference signals(Uref1,Uref2 and Uref3).Using optimization technique,the magnitude of the stepped reference signal is determined so that the total harmonic distortion(THD)of the output voltage waveform is minimum and the fundamental component,RMS value of the voltage is improved for a given modulation index Ma as compared to the sinusoidal pulse width modulation(SPWM).By the implementation of the new scheme,the seven-level of the inverter output voltage level(+Vdc,+2Vdc/3,+Vdc/3,0,−Vdc,−2Vdc/3,−Vdc)is obtained for any given modulation index.Similarly,if only two stepped reference signals are used then the inverter will act as a five-level inverter for any modulating index Ma.The proposed MSPWM and seven-level inverter are simulated on MATLAB/SIMULINK for R,R-L load and on a single-phase capacitor-start and capacitor-start-run Induction Motor.展开更多
文摘Stability and reliability of distribution system are able to be improved by many protective devices including insulators, relay and surge arrester (SA). SA is used for protection of lightning and switching surge in Provincial Electricity Au-thority (PEA). This paper presents an experimental investigation of 22 kV distribution SA electrical performances under pollution conditions according to IEC 60507. The experimental results of leakage currents more than 6 mA at Equiva-lent Salt Deposit Density (ESDD) 0.6 mg/cm2 at nominal voltage. These data will be useful to be guideline for solving problems and reducing power loss from leakage current on the surface of SAs as a result of surface dirt and pollution. Moreover, it will be useful to select or design suitable SAs for using in places with salt conditions, high rainfall, high wind speeds and high humidity.
文摘In this paper a new active RFID system at 2.45 GHz based on the low-power system-on-chip CC2530 RF transceiver is designed and implemented. Only by using of an integrated multi-channel fast chip, both the MCU and RF operations are done which makes the RFID more reliable and reduces the complexity of the hardware and cost, vividly. This RFID system utilizes the Zig-Bee IEEE 802.15.4 standard in the ISM band. A lot amount of energy is restored by setting Tags in the sleep mode in the most of times. The maximum transmission range of 80 m at the output power of 4.5 dBm is obtained. The main application of this system is for the container identification with precise operation and high accuracy. An active Tag with unique ID is mounted on each vehicle. By enabling the AUTOCRC error detection possibility, minor errors are detected in the received frames. Receiver sensitivity of –97 dBm and current consumption of 1 μA in the sleep mode and 29.6 mA in the active mode are reported.
文摘Variable estimation for finishing mill set-up in hot rolling is greatly affected by measurement uncertainties, variations in the incoming bar conditions and product changes. The fuzzy C-means algorithm was evaluated for rule base generation for fuzzy and fuzzy grey-box temperature estimation. Experimental data were collected from a real- life mill and three different sets were randomly drawn. The first set was used for rule-generation, the second set was used for training those systems with learning capabilities, while the third one was used for validation. The perform- ance of the developed systems was evaluated by five performance measures applied over the prediction error with the validation set and was compared with that of the empirical rule-base fuzzy systems and the physical model used in plant. The results show that the fuzzy C-means generated rule-bases improve temperature estimation; however, the best results are obtained when fuzzy C-means algorithm, grey-box modeling and learning functions are combined. Application of fuzzy C-means rule generation brings improvement on performance of up to 72%.
文摘Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.
文摘In this study,the authors have shown the power conversion efficiency of flexible organic solar cells.The structure of the device is PET/ITO/PEDOT:PSS/P3HT:PCBM/AI.P3HT(poly-3-hexylthiophene).It was used as an electron donor,PCBM([6,6]-phenyl C6 l-butyric acid methyl ester)as an electron acceptor and PEDOT:PSS used as a HIL(hole injection layer).These materials were deposited by spin coating method on the flexible substrates.Photolithography method is used to etch ITO.The electrical parameters of the fabricated cells were investigated by means of J(V),FF(fill factor),the efficiency(r/),photocurrent and IPCE measurement.It was observed that 45%of the absorbed photons are converted into current.The results obtained using etching technology by photolithography is better than that obtained in the clean room.
文摘In this work, a new numerical technique is proposed for the resolution of a fluid model based on three Boltzmann moments. The main purpose of this technique is to calculate electric and physical properties in the non-equilibrium electric discharge at low pressure. The transport and Poisson＇s equations form a self-consistent model. This equation system is written in cylindrical coordinates following the geometric shape of a plasma reactor. Our transport equation system is discretized using the finite volume approach and resolved by the N-BEE explicit scheme coupled to the time splitting method. This programming structure reduces computation time considerably. The 2D code is carried out and tested by comparing our results with those found in literature.
文摘Electric vehicles(EVs)have received special consideration from modern society over the past several years.Although EVs are a fine example of environmentally friendly technology and have many advantages,they relatively increase the electricity demand upon a power grid as well.Therefore,their negative impact on busvoltage and line losses should be analyzed.In this study,the effect of EV loads and their penetration on bus voltage and line losses of an IEEE-33 bussystem has been examined via two scenarios.It is important to mention that the effect of EVs on the rate of air pollution,produced by fossil fuel electricity generators,has been investigated throughout the study.Also,the key role of demand response programs in the reduction of EVs’negative effects on the grid has also been discussed in the last scenario.Generally,the simulation of this paper provides a novel and wider perspective on EVs and their effect on grids and environmental pollution.
文摘Single-carrier frequency-division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA) systems are new orthogonal multiple access systems. They have been adopted in the 3GPP long term evolution (3GPP-LTE). In these systems, there are only two types of subcarrier mapping schemes which are the interleaved and the localized. So, introducing a new subcarrier mapping scheme is an important issue, which is the main objective of this paper. In this paper, a hybrid subcarrier mapping scheme is proposed and examined for the SC-FDMA system. Monte Carlo simulations are performed to compare the performance of the proposed scheme with that of the interleaved and the localized schemes. It is shown that a hybrid scheme provides better performance than that of the localized and the same performance as that of the interleaved scheme and increased robustness to carrier frequency offset (CFO) at the expense of increased envelope fluctuations.
文摘We synthesized Zn0.8Fe2.2O4 ferrite powders by coprecipitation and hydrothermal techniques and analyzed the mor-phology and magnetic properties. The morphology and structure of the Zn ferrite powders were investigated using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) identifying the crystallization planes. Magnetic hysteresis curves were obtained for the Zn ferrites samples.
文摘The detection of physiological signals from the motor system （electromyographic signals） is being utilized in the practice clinic to guide the therapist in a more precise and accurate diagnosis of motor disorders. In this context, the process of decomposition of EMG （electromyographic） signals that includes the identification and classification of MUAP （Motor Unit Action Potential） of a EMG signal, is very important to help the therapist in the evaluation of motor disorders. The EMG decomposition is a complex task due to EMG features depend on the electrode type （needle or surface）, its placement related to the muscle, the contraction level and the health of the Neuromuscular System. To date, the majority of researches on EMG decomposition utilize EMG signals acquired by needle electrodes, due to their advantages in processing this type of signal. However, relatively few researches have been conducted using surface EMG signals. Thus, this article aims to contribute to the clinical practice by presenting a technique that permit the decomposition of surface EMG signal via the use of Hidden Markov Models. This process is supported by the use of differential evolution and spectral clustering techniques. The developed system presented coherent results in： （1） identification of the number of Motor Units actives in the EMG signal; （2） presentation of the morphological patterns of MUAPs in the EMG signal; （3） identification of the firing sequence of the Motor Units. The model proposed in this work is an advance in the research area of decomposition of surface EMG signals.
文摘Nowadays Quantum Cellular Automata (QCA) as the leading technology in design of microelectronic systems has been raised. With respect to high velocity and density in low power and also simple concepts, this technology is a viable alternative to CMOS technology. In collector design, the primary component of each processor is very important. Due to the small elements in this technology, failure rate in manufacturing process technology is very high. In the other hand, the simulation shows that the intersection point of two wires is one of the critical points in QCA circuits. This means that defects in the manufacturing process around these points can cause malfunction in the circuit performance. In this paper, a collector in cross sections of wire in his new method used higher reliability against defects during manufacturing has been developed. QCA Designer software is used to simulate the case study system.
基金Southwest Jiaotong University science fund,which of project item was 2002A02
文摘On the basis of transplanting successfully a suit of RTOSμC/OS-Ⅱto MB90F543 MCU,douhle CAN communicating program module have heen embedded intoμC/OS-Ⅱas a building block.Douhle CAN redundant communication have been realized among several hardware nodes based onμC/OS-Ⅱ.The design mechanism,hardware and softy,are of double CAN communication were described in detail.The paper analyze the differences of CAN communication based onμC/OS-Ⅱand traditional foreground/background system.
文摘When the authors research on the fact that some SVC （static var compensator） substations connected at some buses in power system, they realized that some main functions ensured to operate well. Those are： compensate reactive power following value U＊ according to the requirements of the Vietnamese power system dispath center, flit harmonic by passive filter... However, it still has some disadvantages of this substation that need to be overcome： use large number of main devices, generate harmonics by itself, cause a lot of active power losses. Thus, the authors have an idea to solve these problems by applying a bidirectional power converter with having difference circuit structure and PWM （pulse width modulation） controller with SVM （space vector modulation） pulse generated section, so compensative current which is created by inductance element can be reserved, adjust continuos and always has full sinusoidal form, not generating harmonic. The benefit of this new solution is to eliminate the three above fundamental disadvantages. This new model is built based on authors＇ research about BESS （battery energy storage system）. The research results have been verified by simulations in Matlab/Simulink software.
文摘The results of searching of equivalent for electromagnetic transient calculation in power system with the big number of transmission lines are shown. Brief information on the proper transmission line model is given. Comparison of results of simulation in real and reduced system is presented taking into consideration three methods of identification. Some example are examined for different number of transmission lines in reduced system and consequently the recommendation are given for searching of equivalents of systems with many lines.
文摘Dissolved gas analysis is the most widely used diagnostic test in power transformers. The aim of this paper is to introduce the dissolved gas analysis (DGA) methods able to diagnose the transformer conditions. The faults cause the transformer oil, pressboard, and other insulating materials to decompose and generate gases, some of which dissolve in the oil. The results of DGA must be accurate if faults are to be diagnosed reliably. There are different established methods used in industry for interpreting DGA results. We will compare the result of IEEE Key Gas Methods and Rogers’ Ratios. The transformer conditions are evaluated by the Key Gas Method with total combustible gas method (TCGM) and then verified by the Rogers’ Ratios. As result, the aging pattern and trend of the power transformer deterioration can be determined. The 30 sample data from IEEE with known faults and dissolved gas concentrations were used as the basis of comparison.
文摘Nowadays IPP＇s power plant construction is encouraged by the current deregulatory climate. The financing technique employed to implement these projects is often the project financing formula. Under such condition an investor consortium, usually foreigner plan, build, operate the power plant and sell the generated electricity to the host utility. The sale price is determined from the expected IPP＇s production cost, enhanced from the expected welfare obtainable by selling electricity. This paper proposes a methodology for linking the uncertainty of the future production cost with the price of the electricity generated by an IPP. This is a stochastic approach to the sale price definition problem, while usually conducted through a deterministic procedure.
文摘ZnO thin films were deposited using the simple, flexible and cost-effective spray ultrasonic technique at different precursor molarities values. The films were deposited on a glass substrate at 350℃. This paper is to present a new approach to the description of correlation between electrical conductivity and optical gap energy with precursor molarity of ZnO thin films. The ZnO films exhibit higher electrical n-type semiconductors, whose band gap energy increased from 3.08 to 3.37 eV with an increasing of precursor molarity of 0.05 to 0.1 M. The maximum value of electrical conductivity of the films is 7.96 （S2.cm）-1 obtained in the ZnO thin film for precursor molarity 0.125 M. The correlation between the electrical and the optical properties with the precursor molarity suggests that the electrical conductivity of the films is predominantly influenced by the band gap energy and the precursor molarity. The measurement of the electrical conductivity of the films with correlation is equal to the experimental with the error is about 1% in the higher conductivity.
文摘This paper demonstrates the application of optimization techniques,namely the Dung Beetle Optimizer(DBO)and the Ant-Lion Optimizer(ALO),to enhance the performance of cascaded Proportional Integral Derivative(PID)and Fractional Order PID(FOPID)controllers at the edge of an industrial network for Switched Reluctance Motor(SRM)speed control and torque ripple reduction.These techniques present notable advantages in terms of faster convergence and reduced computational complexity compared to existing optimization methods.Our research employs PID and FOPID controllers to regulate the speed and torque of the SRM,with a comparative analysis of other optimization approaches.In the domain of SRM control,we highlight the significance of the hysteresis band block in mitigating sudden state transitions,especially crucial for ensuring stable operation in the presence of noisy or slightly variable input signals requiring precise control.The results underscore the superior performance of the proposed optimization strategies,particularly showcasing the DBO-based cascaded PID and FOPID controllers,which exhibit reduced torque and current ripples along with improved speed response.Our investigation encompasses diverse loading conditions and is substantiated through time-domain simulations performed using MATLAB/SIMULINK.
文摘In this paper, a content based descriptor is pro- posed to retrieve 3D models, which employs histogram of local orientation （HLO） as a geometric property of the shape. The proposed 3D model descriptor scheme consists of three steps. In the first step, Poisson equation is utilized to define a 3D model signature. Next, the local orientation is calculated for each voxel of the model using Hessian matrix. As the final step, a histogram-based 3D model descriptor is extracted by accumulating the values of the local orientation in bins. Due to efficiency of Poisson equation in describing the models with various structures, the proposed descriptor is capable of discriminating these models accurately. Since, the inner vox- els have a dominant contribution in the formation of the de- scriptor, sufficient robustness against noise can be achieved. This is because the noise mostly influences the boundary vox- els. Furthermore, we improve the retrieval performance us- ing support vector machine based one-shot score （SVM-OSS） similarity measure, which is more efficient than the conven- tional methods to compute the distance of feature vectors. The rotation normalization is performed employing the prin- cipal component analysis. To demonstrate the applicability of HLO, we implement experimental evaluations of precision- recall curve on ESB, PSB and WM-SHREC databases of 3D models. Experimental results validate the effectiveness of the proposed descriptor compared to some current methods.
文摘In this paper,a modified sinusoidal pulse width modulation(MSPWM)technique and a modified single-phase H-bridge seven-level inverter is proposed.The switching pulses for the proposed seven-level inverter are generated using a single triangular carrier waveform,a fully rectified sinusoidal signal,and three stepped reference signals(Uref1,Uref2 and Uref3).Using optimization technique,the magnitude of the stepped reference signal is determined so that the total harmonic distortion(THD)of the output voltage waveform is minimum and the fundamental component,RMS value of the voltage is improved for a given modulation index Ma as compared to the sinusoidal pulse width modulation(SPWM).By the implementation of the new scheme,the seven-level of the inverter output voltage level(+Vdc,+2Vdc/3,+Vdc/3,0,−Vdc,−2Vdc/3,−Vdc)is obtained for any given modulation index.Similarly,if only two stepped reference signals are used then the inverter will act as a five-level inverter for any modulating index Ma.The proposed MSPWM and seven-level inverter are simulated on MATLAB/SIMULINK for R,R-L load and on a single-phase capacitor-start and capacitor-start-run Induction Motor.
