For the traditional methods of rotor position estimation for permanent magnet synchronous motor(PMSM),the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some ...For the traditional methods of rotor position estimation for permanent magnet synchronous motor(PMSM),the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some extent.This paper presents an improved rotor position estimation method for high frequency square wave signal injection without filter.Firstly,the traditional method injects high-frequency pulse vibration signals into the estimated shafting,and the proposed method injects high-frequency square wave signals into the estimated shafting to avoid the introduction of filters in the process of extracting rotor position information.Then,the rotor position signal is decoupled in the stationary shafting,and the rotor position error after demodulation is processed by PLL.The system realized the signal processing of rotor position without filter,which improved the convergence speed and estimation precision of rotor position and the dynamic response performance of the system.The simulation results showed that the proposed method had fast convergence speed and small phase delay,and better improved the precision of rotor position detection.展开更多
The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its a...The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its availability and high energy density.This study investigates the synthesis of gold nanoparticles(Au NPs)via a square-wave pulse deposition technique,aiming to enhance catalytic activity for ethanol electrooxidation.By varying pulse durations,we were able to exert precise control over Au NP size and distribution without stabilizing agents.Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase.Electrochemical characteristics analyses revealed that Au NPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area.The electrocatalytic performance test of these Au NPs demonstrated an anodic current density of 2.5 mA cm^-(2)and a Tafel slope of 78 mV dec^(-1),indicating superior catalytic performance and reaction kinetics.Additionally,the Au NPs showed high resistance to poisoning,as evidenced by a low j_(b)/j_(f)ratio of 0.28 and stable chronoamperometric response.These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.展开更多
Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle ...Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.展开更多
The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated th...The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated through dealloying of annealed Fe_(76)Si_(9)B_(15)amorphous ribbons.The results of UV-vis spectra and FTIR indicated that AO II solution was degraded efficiently into unharmful molecules H_(2)O and CO_(2)on NPFe Si B electrode within 5 mins under the square-wave potential of±1.5 V.The degradation efficiency of the NP-Fe Si B electrode remains 98.9%even after 5-time recycling.The large amount of active surface area of the nanoporous Fe Si B electrode with lattice disorders and stacking faults,and alternate electrochemical redox reactions were mainly responsible for the excellent degradation performance of the NP-Fe Si B electrode.The electrochemical pulsed square-wave process accelerated the redox of Fe element in Fe-based nanoporous electrode and promoted the generation of hydroxyl radicals(·OH)with strong oxidizability as predominant oxidants for the degradation of azo dye molecules,which was not only beneficial to improving the catalytic degradation activity,but also beneficial to enhancing the reusability of the nanoporous electrode.This work provides a highly possibility to efficiently degrade azo dyes and broadens the application fields of nanoporous metals.展开更多
Synchronous reluctance machine(SynRM)can be perceived as a special type of permanent magnet synchronous machine(PMSM),and shares similar control method,i.e.the sine-wave current drive with sinusoidal phase currents.In...Synchronous reluctance machine(SynRM)can be perceived as a special type of permanent magnet synchronous machine(PMSM),and shares similar control method,i.e.the sine-wave current drive with sinusoidal phase currents.In this paper,square-wave drive,which is employed for permanent magnet brushless(BLDC)motors,is employed for the SynRM,in order to economically reduce the cost of rotor position sensor.It is revealed that the torque density and efficiency are slightly sacrificed,whereas torque ripple is deteriorated,proving the SynRM with square-wave drive still promising for the cost-sensitive application if torque ripple is not considered as a critical issue.To further investigate the additional pulsating torque under square-wave drive,mathematical model based on a-b-c phase inductance and d-q axis inductance are established,together with the time-stepping FE calculated currents.It is concluded that the harmonics in the currents tend to cause non-sinusoidal variation of the magnetic reluctance,which can be represented as additional inductance harmonics.The harmonics of the current and inductance interact with each other,thus undesirable torque ripple components are produced.展开更多
A sensitive square-wave voltammetric method for the determination of lmidacloprid （IMD） was developed using electrochemically pretreated boron-doped diamond （BDD） electrode. Aqueous solutions were prepared with Co...A sensitive square-wave voltammetric method for the determination of lmidacloprid （IMD） was developed using electrochemically pretreated boron-doped diamond （BDD） electrode. Aqueous solutions were prepared with Confidor 200 SL as the commercial formulation of IMD. Sodium sulfate （Na2SO4） was used as supporting electrolyte. The influence of operating parameters, such as the pH of the medium, frequency, pulse amplitude, scan increment and the concentration of IMD was investigated. An irreversible cathodic peak, corresponding to the reduction oflMD is observed at 1.21 V （vs. SCE） and the electrode reaction was controlled by adsorption. Under optimized conditions, the square-wave reduction peak current was linear over the concentration range of （30-200 μmol L 1） with a detection and quantification limits of 8.60 μmol L 1 and 28.67 μmol L 1, respectively. The results were compared with spectrophotometry and HPLC methods under some conditions and found to be in good agreement. To investigate applicability to real samples, the proposed method was applied to the determination of IMD in plum juice.展开更多
Sine-wave drive and square-wave drive are two common motor control strategies.This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance ...Sine-wave drive and square-wave drive are two common motor control strategies.This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance motors(SynRMs)under these two drive methods,and comparatively analyzes the vibration phenomena induced by electromagnetic forces under different drive methods.It aims to provide an effective tool for predicting the distribution of electromagnetic force waves in SynRMs,while exploring the influence of drive modes on their vibration characteristics.The study focuses on a 4-pole,36-slot 5.5 kW SynRM.Based on the magnetomotive force(MMF)-permeance method,incorporating the special rotor structure and the characteristics of current harmonics under square-wave drive,an air-gap flux distribution function is established.Meanwhile,Maxwell’s stress tensor method is adopted to analyze how the air-gap flux density relates to electromagnetic excitation force waves.Subsequently,this analysis is applied to forecast the spatiotemporal distribution features of radial electromagnetic force waves.Finite element simulations are conducted to compute the modal and vibration responses of the SynRM,followed by a comparative analysis of the vibration characteristics under the two drive methods.Additionally,a 6-pole,36-slot SynRM is used for additional comparative verification.Ultimately,the effectiveness of the simulation results is verified through experiments.展开更多
For the first time, sulfanilamide(SFD) was determined in otologic solution, human urine and serum by electroanalytical techniques on glassy carbon electrode(GCE). The cyclic voltammetry(CV) experiments showed an irrev...For the first time, sulfanilamide(SFD) was determined in otologic solution, human urine and serum by electroanalytical techniques on glassy carbon electrode(GCE). The cyclic voltammetry(CV) experiments showed an irreversible oxidation peak at t 1.06 V in 0.1 mol/L BRBS(p H ? 2.0) at 50 m V/s. Different voltammetric scan rates(from 10 to 250 m V/s) suggested that the oxidation of SFD on the GCE was a diffusioncontrolled process. Square-wave voltammetry(SWV) method under optimized conditions showed a linear response to SFD from 5.0 to 74.7 μmol/L(R ? 0.999) with detection and quantification limits of 0.92 and3.10 μmol/L, respectively. The developed SWV method showed better results for detection limit and linear range than the chronoamperometry method. It has been successfully applied to determine SFD concentration in pharmaceutical formulation, human urine and serum samples with recovery close to 100%.展开更多
The entropic stochastic resonance （ESR） in a confined system subjected to dichotomous noise and white noise and driven by a periodic sinusoidal force along the x axis of the structure and a time-dependent force in t...The entropic stochastic resonance （ESR） in a confined system subjected to dichotomous noise and white noise and driven by a periodic sinusoidal force along the x axis of the structure and a time-dependent force in the declining direction, is investigated. Under the adiabatic approximation condition and based on the two-state theory, the expression of the output signal-to-noise ratio （SNR） is obtained. The results show that the SNR is a non-monotonic function of the strengths of dichotomous noise, white noise, and correlated strength of correlated noise. In addition, the SNR varies non-monotonically with the increase of the shape parameters of the confined structure, and also with the increase of the constant force along the y axis of the structure. The influence of the correlation rate of the dichotomous noise, and that of the frequency of the periodic force on the SNR are discussed.展开更多
The present paper covers the syntheses of 1,8adipoylamidobis(1,10phenanthroline5yl)(bphaa) and its binuclear complex {[(bpy) 2Ru] 2(bphaa)}(PF 6) 4, where bpy is 2,2′bipyridine. The two novel compounds were confi...The present paper covers the syntheses of 1,8adipoylamidobis(1,10phenanthroline5yl)(bphaa) and its binuclear complex {[(bpy) 2Ru] 2(bphaa)}(PF 6) 4, where bpy is 2,2′bipyridine. The two novel compounds were confirmed by means of elemental analysis, IR, LDMS and 1H NMR , and 1H NMR spectra were completely assigned in virtue of 1H 1H COSY. The electrochemical behavior of the binuclear Ru(Ⅱ) complex was obtained using cyclic and squarewave voltammetry. Its photophysical property was investigated by electronic absorption, fluorescence excitation and emission spectra.展开更多
A new electroanalytical procedure was developed for the determination of Benzophenone-3 (BENZO) in commercial sunscreen as the active ingredient. The procedure is based on the use of electrochemical methods as cyclic ...A new electroanalytical procedure was developed for the determination of Benzophenone-3 (BENZO) in commercial sunscreen as the active ingredient. The procedure is based on the use of electrochemical methods as cyclic and square-wave voltammetry, with boron-doped diamond (BDD) electrodes. The reduction of BENZO in Britton-Robinson buffer (0.1 mol●L–1) using this type of electrode gives rise to one irreversible peak in –1.30 V (versus Ag/AgCl) in presence of cationic surfactant cetyltrimethylammonium bromide (CTABr). The proposed electrochemical method was successfully applied to the analysis of commercially available pharmaceutical preparations.展开更多
The main objective of this work was to evaluate the presence of lead and cadmium in galvanized steel tubes by hot-dip used exclusively for drinking water supply.In this research,samples of galvanized tubes were remove...The main objective of this work was to evaluate the presence of lead and cadmium in galvanized steel tubes by hot-dip used exclusively for drinking water supply.In this research,samples of galvanized tubes were removed from walls of residential buildings with 30 years of use.In the process of hot galvanizing,the manufacturing standards allow or for low cost conveniences,and the use of primary zinc ingot with 1.6%metallic impurities,such as lead and cadmium,is allowed,enabling the incorporation of these metals into the zinc coating deposited on the carbon steel.The associated corrosion of these tubes can release these toxic metals,contaminating the drinking water used by residents.The samples taken from the tubes were evaluated by a square-wave anodic stripping voltammetry technique,and the results for lead and cadmium suggested randomly distributed levels,indicating that the contents of these contaminants depend mainly on the quality of the added primary zinc and the operational conditions of the immersion bath.The metallographic evaluations performed on the samples of the galvanized tubes showed irregularities in thickness and even a lack of the zinc layer deposited on the carbon steel surface.These facts suggest that galvanized tubes should not be used for drinking water.展开更多
The response of a bipolar transistor （BJT） under a square-wave electromagnetic pulse （EMP） with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout...The response of a bipolar transistor （BJT） under a square-wave electromagnetic pulse （EMP） with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout time, the damage energy and the injecting voltage is obtained. Research shows that the damage energy is not a constant value, but changes with the injecting voltage level. By use of the device simulator Medici, the internal behavior of the burned device is analyzed. Simulation results indicate that the variation of the damage energy with injecting voltage is caused by the distribution change of hot spot position under different injection levels. Therefore, the traditional way to evaluate the trade-off between the burnout time and the injecting voltage is not comprehensive due to the variation of the damage energy.展开更多
A simple protocol for the chemical modification of graphene with platinum nanoparticles and its subsequent electroanalytical application toward sensitive and selective determination of arsenic has been described.Chemi...A simple protocol for the chemical modification of graphene with platinum nanoparticles and its subsequent electroanalytical application toward sensitive and selective determination of arsenic has been described.Chemical modification was carried out by the simultaneous and sequential chemical reduction of graphene oxide and hexachloroplatinic acid in the presence of ethylene glycol as a mild reducing agent.The synthesized graphene-platinum nanocomposite(Gr-nPt)has been characterized through infrared spectroscopy,x-ray diffraction study,field emission scanning electron microscopy and cyclic voltammetry(CV)techniques.CV and square-wave anodic stripping voltammetry have been used to quantify arsenic.The proposed nanostructure showed linearity in the concentration range 10-100 nM with a detection limit of 1.1 nM.The proposed sensor has been successfully applied to measure trace levels of arsenic present in natural sample matrices like borewell water,polluted lake water,agricultural soil,tomato and spinach leaves.展开更多
基金supported by National Natural Science Foundation of China(No.61863023)Lanzhou Talent Innovation and Entrepreneurship Project Task Contract(No.2019-RC-103).
文摘For the traditional methods of rotor position estimation for permanent magnet synchronous motor(PMSM),the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some extent.This paper presents an improved rotor position estimation method for high frequency square wave signal injection without filter.Firstly,the traditional method injects high-frequency pulse vibration signals into the estimated shafting,and the proposed method injects high-frequency square wave signals into the estimated shafting to avoid the introduction of filters in the process of extracting rotor position information.Then,the rotor position signal is decoupled in the stationary shafting,and the rotor position error after demodulation is processed by PLL.The system realized the signal processing of rotor position without filter,which improved the convergence speed and estimation precision of rotor position and the dynamic response performance of the system.The simulation results showed that the proposed method had fast convergence speed and small phase delay,and better improved the precision of rotor position detection.
基金supported by the National Research and Innovation Agency(BRIN)and Lembaga Pengelola Dana Pendidikan(LPDP)Ministry of Finance,Republic of Indonesia through Riset dan Inovasi Untuk Indonesia Maju(RIIM)scheme batch 2 with contract number 1/PG.02.00.PT/LPPM/IV/2024(110/IV/KS/11/2022).
文摘The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its availability and high energy density.This study investigates the synthesis of gold nanoparticles(Au NPs)via a square-wave pulse deposition technique,aiming to enhance catalytic activity for ethanol electrooxidation.By varying pulse durations,we were able to exert precise control over Au NP size and distribution without stabilizing agents.Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase.Electrochemical characteristics analyses revealed that Au NPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area.The electrocatalytic performance test of these Au NPs demonstrated an anodic current density of 2.5 mA cm^-(2)and a Tafel slope of 78 mV dec^(-1),indicating superior catalytic performance and reaction kinetics.Additionally,the Au NPs showed high resistance to poisoning,as evidenced by a low j_(b)/j_(f)ratio of 0.28 and stable chronoamperometric response.These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.
基金Project (50801056) supported by the National Natural Science Foundation of ChinaProject (2005DKA10400-Z20) supported by the National R&D Infrastructure and Facility Development Program of ChinaProject supported by the Zijin Project of Zhejiang University, China
文摘Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.
基金financially supported by Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,the National Natural Science Foundation of China(51790484,51671106)Chinese Academy of Sciences(ZDBSLY-JSC023)Fundamental Research Funds for the Central Universities(30919011404)。
文摘The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated through dealloying of annealed Fe_(76)Si_(9)B_(15)amorphous ribbons.The results of UV-vis spectra and FTIR indicated that AO II solution was degraded efficiently into unharmful molecules H_(2)O and CO_(2)on NPFe Si B electrode within 5 mins under the square-wave potential of±1.5 V.The degradation efficiency of the NP-Fe Si B electrode remains 98.9%even after 5-time recycling.The large amount of active surface area of the nanoporous Fe Si B electrode with lattice disorders and stacking faults,and alternate electrochemical redox reactions were mainly responsible for the excellent degradation performance of the NP-Fe Si B electrode.The electrochemical pulsed square-wave process accelerated the redox of Fe element in Fe-based nanoporous electrode and promoted the generation of hydroxyl radicals(·OH)with strong oxidizability as predominant oxidants for the degradation of azo dye molecules,which was not only beneficial to improving the catalytic degradation activity,but also beneficial to enhancing the reusability of the nanoporous electrode.This work provides a highly possibility to efficiently degrade azo dyes and broadens the application fields of nanoporous metals.
基金supported in part by the National Natural Science Foundation of China under Grant 52007161.
文摘Synchronous reluctance machine(SynRM)can be perceived as a special type of permanent magnet synchronous machine(PMSM),and shares similar control method,i.e.the sine-wave current drive with sinusoidal phase currents.In this paper,square-wave drive,which is employed for permanent magnet brushless(BLDC)motors,is employed for the SynRM,in order to economically reduce the cost of rotor position sensor.It is revealed that the torque density and efficiency are slightly sacrificed,whereas torque ripple is deteriorated,proving the SynRM with square-wave drive still promising for the cost-sensitive application if torque ripple is not considered as a critical issue.To further investigate the additional pulsating torque under square-wave drive,mathematical model based on a-b-c phase inductance and d-q axis inductance are established,together with the time-stepping FE calculated currents.It is concluded that the harmonics in the currents tend to cause non-sinusoidal variation of the magnetic reluctance,which can be represented as additional inductance harmonics.The harmonics of the current and inductance interact with each other,thus undesirable torque ripple components are produced.
基金financially supported by the Tunisian Ministry of Higher Education and Scientific Research
文摘A sensitive square-wave voltammetric method for the determination of lmidacloprid （IMD） was developed using electrochemically pretreated boron-doped diamond （BDD） electrode. Aqueous solutions were prepared with Confidor 200 SL as the commercial formulation of IMD. Sodium sulfate （Na2SO4） was used as supporting electrolyte. The influence of operating parameters, such as the pH of the medium, frequency, pulse amplitude, scan increment and the concentration of IMD was investigated. An irreversible cathodic peak, corresponding to the reduction oflMD is observed at 1.21 V （vs. SCE） and the electrode reaction was controlled by adsorption. Under optimized conditions, the square-wave reduction peak current was linear over the concentration range of （30-200 μmol L 1） with a detection and quantification limits of 8.60 μmol L 1 and 28.67 μmol L 1, respectively. The results were compared with spectrophotometry and HPLC methods under some conditions and found to be in good agreement. To investigate applicability to real samples, the proposed method was applied to the determination of IMD in plum juice.
基金supported by the Science and Technology Project of State Grid Corporation of China Headquarters under Grant 5500-202416156A-1-1-ZN.
文摘Sine-wave drive and square-wave drive are two common motor control strategies.This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance motors(SynRMs)under these two drive methods,and comparatively analyzes the vibration phenomena induced by electromagnetic forces under different drive methods.It aims to provide an effective tool for predicting the distribution of electromagnetic force waves in SynRMs,while exploring the influence of drive modes on their vibration characteristics.The study focuses on a 4-pole,36-slot 5.5 kW SynRM.Based on the magnetomotive force(MMF)-permeance method,incorporating the special rotor structure and the characteristics of current harmonics under square-wave drive,an air-gap flux distribution function is established.Meanwhile,Maxwell’s stress tensor method is adopted to analyze how the air-gap flux density relates to electromagnetic excitation force waves.Subsequently,this analysis is applied to forecast the spatiotemporal distribution features of radial electromagnetic force waves.Finite element simulations are conducted to compute the modal and vibration responses of the SynRM,followed by a comparative analysis of the vibration characteristics under the two drive methods.Additionally,a 6-pole,36-slot SynRM is used for additional comparative verification.Ultimately,the effectiveness of the simulation results is verified through experiments.
基金UFESCNPq,CAPES(23068719374/2017-70)FAPES(54693900/2011,54694442/2011,60125730/2012,53671880/2011)for the financial support
文摘For the first time, sulfanilamide(SFD) was determined in otologic solution, human urine and serum by electroanalytical techniques on glassy carbon electrode(GCE). The cyclic voltammetry(CV) experiments showed an irreversible oxidation peak at t 1.06 V in 0.1 mol/L BRBS(p H ? 2.0) at 50 m V/s. Different voltammetric scan rates(from 10 to 250 m V/s) suggested that the oxidation of SFD on the GCE was a diffusioncontrolled process. Square-wave voltammetry(SWV) method under optimized conditions showed a linear response to SFD from 5.0 to 74.7 μmol/L(R ? 0.999) with detection and quantification limits of 0.92 and3.10 μmol/L, respectively. The developed SWV method showed better results for detection limit and linear range than the chronoamperometry method. It has been successfully applied to determine SFD concentration in pharmaceutical formulation, human urine and serum samples with recovery close to 100%.
基金Project supported by the Open Fund of Key Laboratory of Education-Ministry Collaboration-Built (Southwest University of Science and Technology)-Manufacturing Process Test Technology,China (Grant No. 11zxzk08)
文摘The entropic stochastic resonance （ESR） in a confined system subjected to dichotomous noise and white noise and driven by a periodic sinusoidal force along the x axis of the structure and a time-dependent force in the declining direction, is investigated. Under the adiabatic approximation condition and based on the two-state theory, the expression of the output signal-to-noise ratio （SNR） is obtained. The results show that the SNR is a non-monotonic function of the strengths of dichotomous noise, white noise, and correlated strength of correlated noise. In addition, the SNR varies non-monotonically with the increase of the shape parameters of the confined structure, and also with the increase of the constant force along the y axis of the structure. The influence of the correlation rate of the dichotomous noise, and that of the frequency of the periodic force on the SNR are discussed.
基金Supported by the Ministry of Science and Technology of China
文摘The present paper covers the syntheses of 1,8adipoylamidobis(1,10phenanthroline5yl)(bphaa) and its binuclear complex {[(bpy) 2Ru] 2(bphaa)}(PF 6) 4, where bpy is 2,2′bipyridine. The two novel compounds were confirmed by means of elemental analysis, IR, LDMS and 1H NMR , and 1H NMR spectra were completely assigned in virtue of 1H 1H COSY. The electrochemical behavior of the binuclear Ru(Ⅱ) complex was obtained using cyclic and squarewave voltammetry. Its photophysical property was investigated by electronic absorption, fluorescence excitation and emission spectra.
文摘A new electroanalytical procedure was developed for the determination of Benzophenone-3 (BENZO) in commercial sunscreen as the active ingredient. The procedure is based on the use of electrochemical methods as cyclic and square-wave voltammetry, with boron-doped diamond (BDD) electrodes. The reduction of BENZO in Britton-Robinson buffer (0.1 mol●L–1) using this type of electrode gives rise to one irreversible peak in –1.30 V (versus Ag/AgCl) in presence of cationic surfactant cetyltrimethylammonium bromide (CTABr). The proposed electrochemical method was successfully applied to the analysis of commercially available pharmaceutical preparations.
文摘The main objective of this work was to evaluate the presence of lead and cadmium in galvanized steel tubes by hot-dip used exclusively for drinking water supply.In this research,samples of galvanized tubes were removed from walls of residential buildings with 30 years of use.In the process of hot galvanizing,the manufacturing standards allow or for low cost conveniences,and the use of primary zinc ingot with 1.6%metallic impurities,such as lead and cadmium,is allowed,enabling the incorporation of these metals into the zinc coating deposited on the carbon steel.The associated corrosion of these tubes can release these toxic metals,contaminating the drinking water used by residents.The samples taken from the tubes were evaluated by a square-wave anodic stripping voltammetry technique,and the results for lead and cadmium suggested randomly distributed levels,indicating that the contents of these contaminants depend mainly on the quality of the added primary zinc and the operational conditions of the immersion bath.The metallographic evaluations performed on the samples of the galvanized tubes showed irregularities in thickness and even a lack of the zinc layer deposited on the carbon steel surface.These facts suggest that galvanized tubes should not be used for drinking water.
基金supported by the National Key Research and Development Project(2018YFB1502401 and 2018YFA0702002)the Program for Changjiang Scholars and Innovation Research Team in the University(IRT1205)+1 种基金the Fundamental Research Funds for the Central Universitiesthe long-term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China。
基金supported by the National Natural Science Foundation of China(No.60776034).
文摘The response of a bipolar transistor （BJT） under a square-wave electromagnetic pulse （EMP） with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout time, the damage energy and the injecting voltage is obtained. Research shows that the damage energy is not a constant value, but changes with the injecting voltage level. By use of the device simulator Medici, the internal behavior of the burned device is analyzed. Simulation results indicate that the variation of the damage energy with injecting voltage is caused by the distribution change of hot spot position under different injection levels. Therefore, the traditional way to evaluate the trade-off between the burnout time and the injecting voltage is not comprehensive due to the variation of the damage energy.
文摘A simple protocol for the chemical modification of graphene with platinum nanoparticles and its subsequent electroanalytical application toward sensitive and selective determination of arsenic has been described.Chemical modification was carried out by the simultaneous and sequential chemical reduction of graphene oxide and hexachloroplatinic acid in the presence of ethylene glycol as a mild reducing agent.The synthesized graphene-platinum nanocomposite(Gr-nPt)has been characterized through infrared spectroscopy,x-ray diffraction study,field emission scanning electron microscopy and cyclic voltammetry(CV)techniques.CV and square-wave anodic stripping voltammetry have been used to quantify arsenic.The proposed nanostructure showed linearity in the concentration range 10-100 nM with a detection limit of 1.1 nM.The proposed sensor has been successfully applied to measure trace levels of arsenic present in natural sample matrices like borewell water,polluted lake water,agricultural soil,tomato and spinach leaves.
