The rapid development of electric vehicles and mobile electronic devices is the main driving force to improve advanced high-performance lithium ion batteries(LIBs).The capacity,rate performance and cycle stability of ...The rapid development of electric vehicles and mobile electronic devices is the main driving force to improve advanced high-performance lithium ion batteries(LIBs).The capacity,rate performance and cycle stability of LIBs rely directly on the electrode materials.As far as the development of the advanced LIBs electrode is concerned,the improvement of anode materials is more urgent than the cathode materials.Industrial production of anode materials superior to commercial graphite still faces some challenges.This review sets out the most basic LIBs anode material design.The reaction principles and structural design of carbon materials,various transition metal oxides,silicon and germanium are summarized,and then the progress of other anode materials are analyzed.Due to the rapid development of metal organic frameworks(MOFs)in energy storage and conversion in recent years,the synthesis process and energy storage mechanism of nanostructures derived from MOF precursors are also discussed.From the perspective of novel structural design,the progress of various MOFs-derived materials for alleviating the volume expansion of anode materials is discussed.Finally,challenges for the future development of advanced anode materials for LIBs will be considered.展开更多
The feasibility of using frequency gradient analysis （FGA）, a digital method based on Fourier transform, to discriminate neutrons and T rays in the environment of an 8-bit sampling system has been investigated. The ...The feasibility of using frequency gradient analysis （FGA）, a digital method based on Fourier transform, to discriminate neutrons and T rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and ~/rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison （CC） methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.展开更多
The complexities of the marine environment and the unique characteristics of underwater channels pose challenges in obtaining reliable signals underwater,necessitating the filtration of underwater acoustic noise.Herei...The complexities of the marine environment and the unique characteristics of underwater channels pose challenges in obtaining reliable signals underwater,necessitating the filtration of underwater acoustic noise.Herein,an underwater acoustic signal denoising method based on ensemble empirical mode decomposition(EEMD),correlation coefficient(CC),permutation entropy(PE),and wavelet threshold denoising(WTD)is proposed.Furthermore,simulation experiments are conducted using simulated and real underwater acoustic data.The experimental results reveal that the proposed denoising method outperforms other previous methods in terms of signal-to-noise ratio,root mean square error,and CC.The proposed method eliminates noise and retains valuable information in the signal.展开更多
Frequency gradient analysis （FGA） effectively discriminates neutrons and γ rays by examining the frequency-domain features of the photomultiplier tube anode signal. This approach is insensitive to noise but is inev...Frequency gradient analysis （FGA） effectively discriminates neutrons and γ rays by examining the frequency-domain features of the photomultiplier tube anode signal. This approach is insensitive to noise but is inevitably affected by the baseline drift similar to other pulse shape discrimination methods. The baseline drift effect is attributed to factors such as power line fluctuation, dark current, noise disturbances, hum, and pulse tail in front-end electronics. This effect needs to be elucidated and quantified before the baseline shift can be estimated and removed from the captured signal. Therefore, the effect of baseline shift on the discrimination performance of neutrons and ~ rays with organic scintillation detectors using FGA is investigated in this paper. The relationship between the baseline shift and discrimination parameters of FGA is derived and verified by an experimental system consisting of an americium-beryllium source, a BC501A liquid scintillator detector, and a 5 GSample/s 8-bit oscilloscope. The theoretical and experimental results both show that the estimation of the baseline shift is necessary, and the removal of baseline drift from the pulse shapes can improve the discrimination performance of FGA.展开更多
We present a low cost radio-frequency （RF） generator suitable for experiments with cold atoms. The RF source achieves a sub-hertz frequency with tunable resolution from 0 MHz to 400 MHz and a maximum output power of...We present a low cost radio-frequency （RF） generator suitable for experiments with cold atoms. The RF source achieves a sub-hertz frequency with tunable resolution from 0 MHz to 400 MHz and a maximum output power of 33 dBm. Based on a direct digital synthesizer （DDS） chip, we implement a ramping capability for frequency, ampli- tude and phase. The system can also operate as an arbitrary waveform generator. By measuring the stability in a dura- tion of 600 s, we fred the presented device performs comparably as Agilent33522A in terms of short-term stability. Due to its excellent performance, the RF generator has been already applied to cold atom trapping experiments.展开更多
This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be convenie...This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be conveniently placed on autonomous underwa- ter vehicles and deployed for adaptive spatial sampling. However, the use of such small aperture passive sonar systems makes it difficult to acquire sufficient spatial gain for localizing long-range sources. To meet the requirement, a localization approach that employs matched-field based techniques that enable the short ho- rizontal linear array is used to passively localize acoustic sources in shallow water. Furthermore, the broadband processing and inter-position processing provide robustness against ocean en- vironmental mismatch and enhance the stability of the estimation process. The proposed approach＇s ability to localize acoustic sources in shallow water at different signal-to-noise ratios is examined through the synthetic test cases where the sources are located at the endfire and some other bearing of the mobile short horizontal linear array. The presented results demonstrate that the positional parameters of the estimated source build up over time as the array moves at a low speed along a straight line at a constant depth.展开更多
We present an innovative and practical scheme of building a miniaturized wavemeter, with the advantages of low cost, high reliability and simple structure. Through a calibration test by a 780 nm external cavity diode ...We present an innovative and practical scheme of building a miniaturized wavemeter, with the advantages of low cost, high reliability and simple structure. Through a calibration test by a 780 nm external cavity diode laser(ECDL), the results show that our system gets a wavelength resolution of better than 1 pm, measurement accuracy of better than 2 pm(corresponding to a frequency of 1 GHz), and a measurement range of 8.5 nm. Finally, the multi-mode comparison test between our system and a commercial spectrum analyzer further indicates the high-precision, miniaturization and low cost of the proposed system, which shows that it is particularly suitable for ECDL and atom cooling and trapping experiments. The system design, experimental results and conclusions are of definite significance as a fine reference for other ranges of wavelength.展开更多
With the rapid development of cold atom physics and quantum optics,Quantum Precision M easurement(QPM)is becoming a more and more active research field.An extreme high measurement precision and sensitivity could be
Objective:UEscope is a new angulated videolaryngoscope (VL).This review aimed to describe the features of UEscope and provide clinical evidences regarding the efficacy and safety of this video device in adult tracheal...Objective:UEscope is a new angulated videolaryngoscope (VL).This review aimed to describe the features of UEscope and provide clinical evidences regarding the efficacy and safety of this video device in adult tracheal intubation and its roles in airway management teaching.Data Sources:The Wan Fang Data,CNKI,PubMed,Embase,Cochrane Library,and Google Scholar were searched for relevant English and Chinese articles published up to January 15,2017,using the following keywords:"HC video laryngoscope","UE videolaryngoscope","video laryngoscope",and "videolaryngoscopy".Study Selection:Human case reports,case series,observable studies,and randomized controlled clinical trials were included in our search.The results of these studies and their reference lists were cross-referenced to identify a common theme.Results:UEscope features the low-profile portable design,intermediate blade curvatures,all-angle adjustable monitor,effective anti-fog mechanisms,and built-in video recording function.During the past 5 years,there have been a number of clinical studies assessing the application and roles of UEscope in airway management and education.As compared with direct laryngoscope,UEscope improves laryngeal visualization,decreases intubation time (IT),and increases intubation success rate in adult patients with normal and difficult airways.These findings are somewhat different from the previous results regarding the other angulated VLs;they can provide an improved laryngeal view,but no conclusive benefits with regard to IT and intubation success rate.Furthermore,UEscope has extensively been used for intubation teaching and shown a number of advantages.Conclusions:UEscope can be used as a primary intubation tool and may provide more benefits than other VLs in patients with normal and difficult airways.However,more studies with large sample are still needed to address some open questions about clinical performance of this new VL.展开更多
According to the SRAM-based FPGA's single event effect problem in space application,single event upset induced multi-block error(SEU-MBE) phenomenon and its mitigation strategy are studied in the paper.After analy...According to the SRAM-based FPGA's single event effect problem in space application,single event upset induced multi-block error(SEU-MBE) phenomenon and its mitigation strategy are studied in the paper.After analyzing the place and route result,the paper points out that the essence of SEU-MBE is that some important modules exceed the safe internal distance.Two approaches,area constraint method(ACM) and incremental route algorithm(IRA),are proposed,which can reduce the error rate by manipulating programmable switch matrix and interconnection points within FPGA route resource.Fault injection experiments indicate that error detection rate is above 98.6% for both strategies,and FPGA resources increment and performance penalty are around 10%.展开更多
The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interfa...The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interface can exist in large amounts of crystalline or amorphous states.However,the experimental evidence of coexistence of liquid water phases at interface is still insufficient.Here,a special folding few-layers graphene film was elaborate prepared to form a hydrophobic/hydrophobic interface,which can provide a suited platform to study the structure and properties of confined liquid water.The real-space visualization of intercalated water layers phases at the folding interface is obtained using advanced atomic force microscopy(AFM).The folding graphene interface displays complicated internal interfacial characteristics.The intercalated water molecules present themselves as two phases,low-density liquid(LDL,solid-like)and high-density liquid(HDL,liquid-like),according to their specific mechanical properties taken in two multifrequency-AFM(MF-AFM)modes.Furthermore,the water molecules structural evolution is demonstrated in a series of continuous MF-AFM measurements.The work preliminary confirms the existence of two liquid phases of water in real space and will inspire further experimental work to deeply understanding their liquid dynamics behavior.展开更多
Nickel hydroxide, Ni（OH）2 is widely used in electrodes of nickel-based alkaline secondary batteries, Ultrathin hexagonal Ni（OH）2 nanosheets of space group P-3ml were hydrothermally prepared at 200℃ for 10h. Their...Nickel hydroxide, Ni（OH）2 is widely used in electrodes of nickel-based alkaline secondary batteries, Ultrathin hexagonal Ni（OH）2 nanosheets of space group P-3ml were hydrothermally prepared at 200℃ for 10h. Their diameter and thickness were 200-300 and 3-5 nm, respectively, Their formation was attributed to the oriented assembly of growing particles, which was assisted by surfactant molecules. The specific surface area of the Ni（OH）2 nanosheets was 8.66 m2/g. Their magnetization curve exhibited linear paramagnetic behavior across the entire measurement region.展开更多
Highly-dispersed BaLuFs：yb3＋/Er3＋ nanocrystals were prepared by a facile potassium sodium tartrate- assisted hydrothermal method. The average particle size was approximately 20-25 nm. The formation mechanism is dis...Highly-dispersed BaLuFs：yb3＋/Er3＋ nanocrystals were prepared by a facile potassium sodium tartrate- assisted hydrothermal method. The average particle size was approximately 20-25 nm. The formation mechanism is discussed. Potassium sodium tartrate led to form a complex with an approximately three- dimensional network structure, which insured largely concurrent nucleation. As a result, we acquired uniform nanoparticles. The hydrothermal temperature, holding time, and pH value were important fac- tors affecting the formation of the BaLuF5 ：yb3＋/Er3＋ nanocrystals. We investigated their influence on the formation and realized the optimal reaction parameters. Remarkably, potassium sodium tartrate also con- tributed to the biocompatibility and potential biomedical applications of BaLuFs ：Yb3＋/Er3＋ nanocrystals by decomposing into small organic groups attached to the nanoparticles.展开更多
Owing to the extensive use of fossil fuels for energy,environmental problems are becoming increasingly severe.Therefore,renewable clean energy sources must be urgently developed.As an environmentally friendly electroc...Owing to the extensive use of fossil fuels for energy,environmental problems are becoming increasingly severe.Therefore,renewable clean energy sources must be urgently developed.As an environmentally friendly electrochemical energy-storage system,lithium-ion batteries(LIBs)are widely used in portable devices,electric vehicles,and medical equipment.However,owing to their high cost and low theoretical energy density,LIBs are far from meeting the current energy demand.Lithium-sulfur batteries(LSBs)(wherein lithium metal and sulfur are the anode and cathode,respectively)are one of the most valuable secondary batteries because of their high theoretical energy density(-2600Whkg^(-1)).However,the intrinsic conductivity of sulfur cathode materials is poor,and the lithium polysulfide formed during lithiation dissolves easily.Moreover,the volumetric expansion during charging and discharging adversely affects the LSB electrochemical performance,including the rate performance,cycle life,and coulombic efficiency.Therefore,to improve the LSB electrochemical performance,various sulfur composites have been prepared using carbon materials,metallic oxides,and conductive polymers,and various composite cathode materials recently developed for application to LSBs were reviewed.Finally,research directions were proposed for modifying LSB cathode materials.展开更多
We present a compact, low-noise, and inexpensive optical phase-lock loop （OPLL） system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer tech-...We present a compact, low-noise, and inexpensive optical phase-lock loop （OPLL） system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer tech- nique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.展开更多
We present a laser frequency locking system based on acousto-optic modulation transfer spectroscopy（AOMTS）. Theoretical and experimental investigations are carried out to optimize the locking performance mainly from...We present a laser frequency locking system based on acousto-optic modulation transfer spectroscopy（AOMTS）. Theoretical and experimental investigations are carried out to optimize the locking performance mainly from the view of the modulation frequency and index for the specific scheme of AOMTS. An FWHM linewidth of 63 kHz is achieved and the frequency stability in terms of Allan standard deviation reaches1.4 × 10^（-12） at 30 s. The frequency shifting capacity is validated throughout the acousto-optic modulator bandwidth while the laser is kept locked. This work offers a different but efficient choice for applications calling for both stabilized and tunable laser frequencies.展开更多
In atomic force microscopy(AFM), high-frequency components consisted in dynamic tip-sample interaction have been recently demonstrated as a promising technique for exploring more extensive material properties. Here we...In atomic force microscopy(AFM), high-frequency components consisted in dynamic tip-sample interaction have been recently demonstrated as a promising technique for exploring more extensive material properties. Here we present an exploratory study of high harmonic atomic force microscopy by force-spectroscopy and high harmonic imaging. Since these components are very weak compared to the fundamental response, we firstly designed a high harmonic cantilever by tuning the second order flexural resonance frequency to an integer 6 times of its fundamental mode(i.e. ω_2=6ω_1). Moreover, it is verified that high harmonic can discern extra features than topographies on different samples with amplitude/frequency modulation(AM/FM) dynamic AFM mode. In AM mode, the first resonance amplitude and 6 th harmonic amplitude were discussed. The 6 th harmonic is more sensitive than the first order response. In FM mode, it is noted that the decaying rate of the 6 th harmonic frequency is approximately 6 multiples to the slope of the fundamental frequency shift when the tip approaches to the surface of sample. This non-destructive method was also adopted to investigate the local interlayer coupling and intercalation in the two-dimensional graphene films tentatively.展开更多
基金financial support from the National Natural Science Foundation of China(81671737)the support from‘Sponsored by Shanghai Pujiang Program’(18PJD020)the Interdisciplinary Program of Shanghai Jiao Tong University(YG2019QNB31)。
文摘The rapid development of electric vehicles and mobile electronic devices is the main driving force to improve advanced high-performance lithium ion batteries(LIBs).The capacity,rate performance and cycle stability of LIBs rely directly on the electrode materials.As far as the development of the advanced LIBs electrode is concerned,the improvement of anode materials is more urgent than the cathode materials.Industrial production of anode materials superior to commercial graphite still faces some challenges.This review sets out the most basic LIBs anode material design.The reaction principles and structural design of carbon materials,various transition metal oxides,silicon and germanium are summarized,and then the progress of other anode materials are analyzed.Due to the rapid development of metal organic frameworks(MOFs)in energy storage and conversion in recent years,the synthesis process and energy storage mechanism of nanostructures derived from MOF precursors are also discussed.From the perspective of novel structural design,the progress of various MOFs-derived materials for alleviating the volume expansion of anode materials is discussed.Finally,challenges for the future development of advanced anode materials for LIBs will be considered.
基金Supported by National Natural Science Foundation of China (A050508/11175254)
文摘The feasibility of using frequency gradient analysis （FGA）, a digital method based on Fourier transform, to discriminate neutrons and T rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and ~/rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison （CC） methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.
基金Supported by the National Natural Science Foundation of China(No.62033011)Science and Technology Project of Hebei Province(No.216Z1704G,No.20310401D)。
文摘The complexities of the marine environment and the unique characteristics of underwater channels pose challenges in obtaining reliable signals underwater,necessitating the filtration of underwater acoustic noise.Herein,an underwater acoustic signal denoising method based on ensemble empirical mode decomposition(EEMD),correlation coefficient(CC),permutation entropy(PE),and wavelet threshold denoising(WTD)is proposed.Furthermore,simulation experiments are conducted using simulated and real underwater acoustic data.The experimental results reveal that the proposed denoising method outperforms other previous methods in terms of signal-to-noise ratio,root mean square error,and CC.The proposed method eliminates noise and retains valuable information in the signal.
基金Supported by National Natural Science Foundation of China(11175254)the support of the Institute of Nuclear Physics and Chemistry, the Chinese Academy of Engineering Physics, Mianyang, China
文摘Frequency gradient analysis （FGA） effectively discriminates neutrons and γ rays by examining the frequency-domain features of the photomultiplier tube anode signal. This approach is insensitive to noise but is inevitably affected by the baseline drift similar to other pulse shape discrimination methods. The baseline drift effect is attributed to factors such as power line fluctuation, dark current, noise disturbances, hum, and pulse tail in front-end electronics. This effect needs to be elucidated and quantified before the baseline shift can be estimated and removed from the captured signal. Therefore, the effect of baseline shift on the discrimination performance of neutrons and ~ rays with organic scintillation detectors using FGA is investigated in this paper. The relationship between the baseline shift and discrimination parameters of FGA is derived and verified by an experimental system consisting of an americium-beryllium source, a BC501A liquid scintillator detector, and a 5 GSample/s 8-bit oscilloscope. The theoretical and experimental results both show that the estimation of the baseline shift is necessary, and the removal of baseline drift from the pulse shapes can improve the discrimination performance of FGA.
基金This work has been supported by the National Natural Science Foundation of China(No.51275523)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20134307110009)
文摘We present a low cost radio-frequency （RF） generator suitable for experiments with cold atoms. The RF source achieves a sub-hertz frequency with tunable resolution from 0 MHz to 400 MHz and a maximum output power of 33 dBm. Based on a direct digital synthesizer （DDS） chip, we implement a ramping capability for frequency, ampli- tude and phase. The system can also operate as an arbitrary waveform generator. By measuring the stability in a dura- tion of 600 s, we fred the presented device performs comparably as Agilent33522A in terms of short-term stability. Due to its excellent performance, the RF generator has been already applied to cold atom trapping experiments.
基金supported by the State Scholarship Fund(2011611091)supported by China Shipbuilding Industry Corporation
文摘This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be conveniently placed on autonomous underwa- ter vehicles and deployed for adaptive spatial sampling. However, the use of such small aperture passive sonar systems makes it difficult to acquire sufficient spatial gain for localizing long-range sources. To meet the requirement, a localization approach that employs matched-field based techniques that enable the short ho- rizontal linear array is used to passively localize acoustic sources in shallow water. Furthermore, the broadband processing and inter-position processing provide robustness against ocean en- vironmental mismatch and enhance the stability of the estimation process. The proposed approach＇s ability to localize acoustic sources in shallow water at different signal-to-noise ratios is examined through the synthetic test cases where the sources are located at the endfire and some other bearing of the mobile short horizontal linear array. The presented results demonstrate that the positional parameters of the estimated source build up over time as the array moves at a low speed along a straight line at a constant depth.
基金supported by the National Natural Science Foundation of China(No.51275523)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20134307110009)+1 种基金the Graduate Innovative Research Fund of Hunan Province(No.CX20158015)the Excellent Graduate Innovative Fund of NUDT(No.B150305)
文摘We present an innovative and practical scheme of building a miniaturized wavemeter, with the advantages of low cost, high reliability and simple structure. Through a calibration test by a 780 nm external cavity diode laser(ECDL), the results show that our system gets a wavelength resolution of better than 1 pm, measurement accuracy of better than 2 pm(corresponding to a frequency of 1 GHz), and a measurement range of 8.5 nm. Finally, the multi-mode comparison test between our system and a commercial spectrum analyzer further indicates the high-precision, miniaturization and low cost of the proposed system, which shows that it is particularly suitable for ECDL and atom cooling and trapping experiments. The system design, experimental results and conclusions are of definite significance as a fine reference for other ranges of wavelength.
文摘With the rapid development of cold atom physics and quantum optics,Quantum Precision M easurement(QPM)is becoming a more and more active research field.An extreme high measurement precision and sensitivity could be
文摘Objective:UEscope is a new angulated videolaryngoscope (VL).This review aimed to describe the features of UEscope and provide clinical evidences regarding the efficacy and safety of this video device in adult tracheal intubation and its roles in airway management teaching.Data Sources:The Wan Fang Data,CNKI,PubMed,Embase,Cochrane Library,and Google Scholar were searched for relevant English and Chinese articles published up to January 15,2017,using the following keywords:"HC video laryngoscope","UE videolaryngoscope","video laryngoscope",and "videolaryngoscopy".Study Selection:Human case reports,case series,observable studies,and randomized controlled clinical trials were included in our search.The results of these studies and their reference lists were cross-referenced to identify a common theme.Results:UEscope features the low-profile portable design,intermediate blade curvatures,all-angle adjustable monitor,effective anti-fog mechanisms,and built-in video recording function.During the past 5 years,there have been a number of clinical studies assessing the application and roles of UEscope in airway management and education.As compared with direct laryngoscope,UEscope improves laryngeal visualization,decreases intubation time (IT),and increases intubation success rate in adult patients with normal and difficult airways.These findings are somewhat different from the previous results regarding the other angulated VLs;they can provide an improved laryngeal view,but no conclusive benefits with regard to IT and intubation success rate.Furthermore,UEscope has extensively been used for intubation teaching and shown a number of advantages.Conclusions:UEscope can be used as a primary intubation tool and may provide more benefits than other VLs in patients with normal and difficult airways.However,more studies with large sample are still needed to address some open questions about clinical performance of this new VL.
基金supported by the National High Technology Research and Development Program of China ("863" Program) (Grant No. 2006SQ710375)the Civil Aerospace Technologies Advanced Research Pro-gram of China (Grant No. C1320061301)Ministries and Commissions’Advanced Research Found of China (Grant No. 9140A20070209KG0160)
文摘According to the SRAM-based FPGA's single event effect problem in space application,single event upset induced multi-block error(SEU-MBE) phenomenon and its mitigation strategy are studied in the paper.After analyzing the place and route result,the paper points out that the essence of SEU-MBE is that some important modules exceed the safe internal distance.Two approaches,area constraint method(ACM) and incremental route algorithm(IRA),are proposed,which can reduce the error rate by manipulating programmable switch matrix and interconnection points within FPGA route resource.Fault injection experiments indicate that error detection rate is above 98.6% for both strategies,and FPGA resources increment and performance penalty are around 10%.
基金the Ministry of Science and Technology(MOST)of China(No.2016YFA0200700)the National Natural Science Foun-dation of China(NSFC)(Nos.21622304,61674045,and 11604063)+1 种基金the Strategic Priority Research Program,the Key Research Program of Frontier Sciences and Instrument Developing Project of Chinese Academy of Sciences(CAS)(Nos.XDB30000000,QYZDB-SSW-SYS031,and YZ201418)Z.H.Cheng was supported by Distinguished Technical Talents Project and Youth Innovation Promotion Association CAS,the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No.18XNLG01).
文摘The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interface can exist in large amounts of crystalline or amorphous states.However,the experimental evidence of coexistence of liquid water phases at interface is still insufficient.Here,a special folding few-layers graphene film was elaborate prepared to form a hydrophobic/hydrophobic interface,which can provide a suited platform to study the structure and properties of confined liquid water.The real-space visualization of intercalated water layers phases at the folding interface is obtained using advanced atomic force microscopy(AFM).The folding graphene interface displays complicated internal interfacial characteristics.The intercalated water molecules present themselves as two phases,low-density liquid(LDL,solid-like)and high-density liquid(HDL,liquid-like),according to their specific mechanical properties taken in two multifrequency-AFM(MF-AFM)modes.Furthermore,the water molecules structural evolution is demonstrated in a series of continuous MF-AFM measurements.The work preliminary confirms the existence of two liquid phases of water in real space and will inspire further experimental work to deeply understanding their liquid dynamics behavior.
基金financial support from the National Innovation Engineering Program for new Energy Vehicle Industry Technology, National Natural Science Foundation of China(No.81225010)863 High-Tech Project of China(2012AA022603)
文摘Nickel hydroxide, Ni（OH）2 is widely used in electrodes of nickel-based alkaline secondary batteries, Ultrathin hexagonal Ni（OH）2 nanosheets of space group P-3ml were hydrothermally prepared at 200℃ for 10h. Their diameter and thickness were 200-300 and 3-5 nm, respectively, Their formation was attributed to the oriented assembly of growing particles, which was assisted by surfactant molecules. The specific surface area of the Ni（OH）2 nanosheets was 8.66 m2/g. Their magnetization curve exhibited linear paramagnetic behavior across the entire measurement region.
文摘Highly-dispersed BaLuFs：yb3＋/Er3＋ nanocrystals were prepared by a facile potassium sodium tartrate- assisted hydrothermal method. The average particle size was approximately 20-25 nm. The formation mechanism is discussed. Potassium sodium tartrate led to form a complex with an approximately three- dimensional network structure, which insured largely concurrent nucleation. As a result, we acquired uniform nanoparticles. The hydrothermal temperature, holding time, and pH value were important fac- tors affecting the formation of the BaLuF5 ：yb3＋/Er3＋ nanocrystals. We investigated their influence on the formation and realized the optimal reaction parameters. Remarkably, potassium sodium tartrate also con- tributed to the biocompatibility and potential biomedical applications of BaLuFs ：Yb3＋/Er3＋ nanocrystals by decomposing into small organic groups attached to the nanoparticles.
基金financial support from the National Natural Science Foundation of China(81671737,91634108)the Interdisciplinary Program of Shanghai Jiao Tong University(YG2021QN102,YG2021QN65 and YG2019QNB31).
文摘Owing to the extensive use of fossil fuels for energy,environmental problems are becoming increasingly severe.Therefore,renewable clean energy sources must be urgently developed.As an environmentally friendly electrochemical energy-storage system,lithium-ion batteries(LIBs)are widely used in portable devices,electric vehicles,and medical equipment.However,owing to their high cost and low theoretical energy density,LIBs are far from meeting the current energy demand.Lithium-sulfur batteries(LSBs)(wherein lithium metal and sulfur are the anode and cathode,respectively)are one of the most valuable secondary batteries because of their high theoretical energy density(-2600Whkg^(-1)).However,the intrinsic conductivity of sulfur cathode materials is poor,and the lithium polysulfide formed during lithiation dissolves easily.Moreover,the volumetric expansion during charging and discharging adversely affects the LSB electrochemical performance,including the rate performance,cycle life,and coulombic efficiency.Therefore,to improve the LSB electrochemical performance,various sulfur composites have been prepared using carbon materials,metallic oxides,and conductive polymers,and various composite cathode materials recently developed for application to LSBs were reviewed.Finally,research directions were proposed for modifying LSB cathode materials.
基金supported by the National Natural Science Foundation(No.51275523)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20134307110009) of China
文摘We present a compact, low-noise, and inexpensive optical phase-lock loop （OPLL） system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer tech- nique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.
基金supported by the National Natural Science Foundation(No.51275523)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20134307110009)of China
文摘We present a laser frequency locking system based on acousto-optic modulation transfer spectroscopy（AOMTS）. Theoretical and experimental investigations are carried out to optimize the locking performance mainly from the view of the modulation frequency and index for the specific scheme of AOMTS. An FWHM linewidth of 63 kHz is achieved and the frequency stability in terms of Allan standard deviation reaches1.4 × 10^（-12） at 30 s. The frequency shifting capacity is validated throughout the acousto-optic modulator bandwidth while the laser is kept locked. This work offers a different but efficient choice for applications calling for both stabilized and tunable laser frequencies.
基金supported by the Ministry of Science and Technology(MOST)of China(Grant No.2016YFA0200700)the National Natural Science Foundation of China(Grant Nos.21622304,61674045,11604063)+2 种基金Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SYS031)Osaka University's International Joint Research Promotion Program(Grant Nos.J171013014,J171013007)Distinguished Technical Talents Project and Youth Innovation Promotion Association,Chinese Academy of Sciences
文摘In atomic force microscopy(AFM), high-frequency components consisted in dynamic tip-sample interaction have been recently demonstrated as a promising technique for exploring more extensive material properties. Here we present an exploratory study of high harmonic atomic force microscopy by force-spectroscopy and high harmonic imaging. Since these components are very weak compared to the fundamental response, we firstly designed a high harmonic cantilever by tuning the second order flexural resonance frequency to an integer 6 times of its fundamental mode(i.e. ω_2=6ω_1). Moreover, it is verified that high harmonic can discern extra features than topographies on different samples with amplitude/frequency modulation(AM/FM) dynamic AFM mode. In AM mode, the first resonance amplitude and 6 th harmonic amplitude were discussed. The 6 th harmonic is more sensitive than the first order response. In FM mode, it is noted that the decaying rate of the 6 th harmonic frequency is approximately 6 multiples to the slope of the fundamental frequency shift when the tip approaches to the surface of sample. This non-destructive method was also adopted to investigate the local interlayer coupling and intercalation in the two-dimensional graphene films tentatively.
