Hydraulic rolling reshaper is an advanced reshaping tool to solve the problem of casing deformation,which has been widely used in recent years.When it is used for well repair operation,the reshaping force provided by ...Hydraulic rolling reshaper is an advanced reshaping tool to solve the problem of casing deformation,which has been widely used in recent years.When it is used for well repair operation,the reshaping force provided by ground devices is generally determined by experience.However,too large reshaping force may destroy the deformed casing,and too small reshaping force may also prolong the construction period and affect the repairing effect.In this paper,based on Hertz contact theory and elastic-plastic theory,combined with the process parameters of shaping,and considering the structural characteristics of the deformed casing and reshaper,we propose a mathematical model for calculating the reshaping force required for repairing deformed casing by hydraulic rolling reshaper.Meanwhile,the finite element model and numerical method of hydraulic rolling reshaper repairing deformed casing are established by using the finite element method,and the reliability of the mathematical model is verified by several examples.On this basis,the control variable method is used to investigate the influence of each parameter on the reshaping force,and the influence degree of each parameter is explored by orthogonal simulation test and Pearson correlation analysis.The research results not only provide an important theoretical basis for the prediction of reshaping force in on-site construction,but also provide a reference for the subsequent improvement of the shaping process.展开更多
Whether a new generation of human rights emerges in the digital age has sparked widespread debate.Academic understanding of digital technology remains confined to thinking about network technology and products,often o...Whether a new generation of human rights emerges in the digital age has sparked widespread debate.Academic understanding of digital technology remains confined to thinking about network technology and products,often overlooking the revolutionary nature of digital media.Digital media has the sweeping potential to unify all forms of media and reshape social life,giving rise to new demands for a new generation of human rights.The concept of digital human rights can be defined as the legitimate rights of human's infinitely extended personalities through digital media.Its core characteristic is its transcendency,where every person lives in a networked space that surpasses physical boundaries,nations,and individual personalities.Human rights are generally considered the foundation for basic constitutional rights,which,in turn,form the basis for legislative acts across various sectors.In recent years,China has enacted numerous laws in the digital domain to keep pace with the times,but due to the lack of guidance on digital human rights,these laws tend to be fragmented and disjointed.It is urgent to unify digital legislation at all levels on the basis of reshaping basic constitutional rights.Thus,it is essential to reshape the basic rights based on the concept and characteristics of digital human rights and streamline legislation at all levels under the unified guidance of basic rights.This can help establish a comprehensive digital human rights protection system that meets the demands of the modern era.展开更多
An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdope...An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.展开更多
In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency poi...In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency points can be characterized by a polynomial.And in the practical test,the coefficients of SSF can be determined by measuring a small number of data points of input power.Same as other dualinput DPAs,the proposed approach can also achieve high output power and back-off efficiency in a broadband operation band by adjusting the power distribution ratio flexibly.Finally,a 1.5-2.5 GHz highefficiency dual-input Doherty power amplifier is implemented according to this approach.The test results show that the peak power is 48.6-49.7d Bm,and the 6-d B back-off efficiency is 51.0-67.0%,and the saturation efficiency is 52.4-74.6%.The digital predistortion correction is carried out at the frequency points of 1.8/2.1GHz,and the adjacent channel power ratio is lower than-54.5d Bc.Simulation and experiment results can verify the effectiveness and correctness of the proposed method.展开更多
Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.Howe...Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.展开更多
In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabric...In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)application.An inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small area.The proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 dBm.The gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 GHz.The measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.展开更多
A Josephson traveling wave parametric amplifier(JTWPA),which is a quantum-limited amplifier with high gain and large bandwidth,is the core device of large-scale measurement and control systems for quantum computing.A ...A Josephson traveling wave parametric amplifier(JTWPA),which is a quantum-limited amplifier with high gain and large bandwidth,is the core device of large-scale measurement and control systems for quantum computing.A typical JTWPA consists of thousands of Josephson junctions connected in series to form a transmission line and hundreds of shunt LC resonators periodically loaded along the line for phase matching.Because the variation of these capacitors and inductors can be detrimental to their high-frequency characteristics,the fabrication of a JTWPA typically necessitates precise processing equipment.To guide the fabrication process and further improve the design for manufacturability,it is necessary to understand how each electronic component affects the amplifier.In this paper,we use the harmonic balance method to conduct a comprehensive study on the impact of nonuniformity and fabrication yield of the electronic components on the performance of a JTWPA.The results provide insightful and scientific guidance for device design and fabrication processes.展开更多
For time-of-flight(TOF)light detection and ranging(LiDAR),a three-channel high-performance transimpedance amplifier(TIA)with high immunity to input load capacitance is presented.A regulated cascade(RGC)as the input st...For time-of-flight(TOF)light detection and ranging(LiDAR),a three-channel high-performance transimpedance amplifier(TIA)with high immunity to input load capacitance is presented.A regulated cascade(RGC)as the input stage is at the core of the complementary metal oxide semiconductor(CMOS)circuit chip,giving it more immunity to input photodiode detectors.A simple smart output interface acting as a feedback structure,which is rarely found in other designs,reduces the chip size and power consumption simultaneously.The circuit is designed using a 0.5μm CMOS process technology to achieve low cost.The device delivers a 33.87 dB?transimpedance gain at 350 MHz.With a higher input load capacitance,it shows a-3 dB bandwidth of 461 MHz,indicating a better detector tolerance at the front end of the system.Under a 3.3 V supply voltage,the device consumes 5.2 mW,and the total chip area with three channels is 402.8×597.0μm2(including the test pads).展开更多
To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and co...To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and communication(RadCom)systems is studied,the channel estimation in passive sensing scenarios.Adaptive channel estimation methods are proposed based on different pilot patterns,considering nonlinear distortion and channel sparsity.The proposed methods achieve sparse channel results by manipulating the least squares(LS)frequency-domain channel estimation results to preserve the most significant taps.The decision-aided method is used to optimize the sparse channel results to reduce the effect of nonlinear distortion.Numerical results show that the channel estimation performance of the proposed methods is better than that of the conventional methods under different pilot patterns.In addition,the bit error rate performance in communication and passive radar detection performance show that the proposed methods have good comprehensive performance.展开更多
An actual ecological predator-prey system often undergoes random environmental mutations owing to the impact of natural disasters and man-made destruction, which may destroy the balance between the species. In this pa...An actual ecological predator-prey system often undergoes random environmental mutations owing to the impact of natural disasters and man-made destruction, which may destroy the balance between the species. In this paper,the stochastic dynamics of the nonlinear predator-prey system considering random environmental mutations is investigated, and a feedback control strategy is proposed to reshape the response of the predator-prey system against random abrupt environmental mutations. A delayed Markov jump system(MJS) is established to model such a predator-prey system. A novel first integral is constructed which leads to better approximation solutions of the ecosystem. Then, by applying the stochastic averaging method based on this novel first integral, the stochastic response of the predator-prey system is investigated, and an analytical feedback control is designed to reshape the response of the ecosystem from the disturbed state back to the undisturbed one.Numerical simulations finally illustrate the accuracy and effectiveness of the proposed procedure.展开更多
The homodimeric kinesin-2 protein KIF17 functions in intracellular transport and spermiogenesis in mammals.However,its role in fish spermiogenesis has not been reported.Here,we aimed to clone full-length kif17 cDNA an...The homodimeric kinesin-2 protein KIF17 functions in intracellular transport and spermiogenesis in mammals.However,its role in fish spermiogenesis has not been reported.Here,we aimed to clone full-length kif17 cDNA and determine the molecular characteristics and expression patterns of KIF17 in Larimichthys polyactis spermiogenesis.The full-length cDNA of L.polyactis kif17(Lp-kif17)was sequenced and found to contain a 332-bp 5′untranslated region,480-bp 3′untranslated region,and 2433-bp open reading frame encoding 810 amino acids.Bioinformatics analyses showed that L.polyactis KIF17(Lp-KIF17)shared high sequence similarity with homologs in other animals and possessed an N-terminal motor domain with microtubule-binding sites and adenosine triphosphate(ATP)hydrolysis sites,a stalk domain containing two coiled-coil regions,and a C-terminal tail domain.The Lp-kif17 mRNA was widely expressed in various tissues,with the highest level in the brain,followed by that in the testis.Fluorescence in situ hybridization(FISH)analysis revealed that Lp-kif17 was continuously expressed in spermiogenesis,showing that it had potential functions in this process.Using immunofluorescence(IF)analysis,we found that Lp-KIF17 colocalized with tubulin and was transferred from the perinuclear cytoplasm to the side of spermatid where the tail forms during spermiogenesis.These findings suggested that KIF17 is involved in L.polyactis spermiogenesis.In particular,it may participate in nuclear shaping and tail formation by interacting with perinuclear microtubules during spermatid reshaping.In addition to providing evidence for the role of KIF17 in fish spermatid reshaping,this study provides important data for studies of reproductive biology in L.polyactis.展开更多
In this paper,a 5G wideband power amplifier(PA)with bandpass filtering response is synthesized using a bandwidth-extended bandpass filter as the matching network(MN).In this structure,the bandwidth(θ_(C))is defined a...In this paper,a 5G wideband power amplifier(PA)with bandpass filtering response is synthesized using a bandwidth-extended bandpass filter as the matching network(MN).In this structure,the bandwidth(θ_(C))is defined as a variable in the closedform equations provided by the microstrip bandpass filter.It can be extended over a wide range only by changing the characteristic impedances of the structure.Different from the other wideband MNs,the extension of bandwidth does not increase the complexity of the structure(order n is fixed).In addition,based on the bandwidth-extended structure,the wideband design of bandpass filtering PA is not limited to the fixed bandwidth of the specific filter structure.The theoretical analysis of the MN and the design flow of the PA are provided in this design.The fabricated bandpass filtering PA can support almost one-octave bandwidth(2-3.8 GHz),covering the two 5G bands(n41 and n78).The drain efficiency of 47%-60%and output power higher than 40 dBm are measured.Good frequency selectivity in S-parameter measurements can be observed.展开更多
Considering the R&D for upgrading the K^(0)_(L) andμdetectors in the Belle II experiment using a scintillator and silicon pho-tomultiplier(SiPM),we designed a compact high-speed and low-noise preamplifier.The pre...Considering the R&D for upgrading the K^(0)_(L) andμdetectors in the Belle II experiment using a scintillator and silicon pho-tomultiplier(SiPM),we designed a compact high-speed and low-noise preamplifier.The preamplifier demonstrated a good gain stability,bandwidth of 426 MHz,baseline noise level ofσ≈0.6 mV,dynamic range of up to170 mV of the input signal amplitude,good time resolution of 20 ps,and it can be comprehensively applied to SiPMs.Adopting pole-zero-cancelation in the preamplifier reduces both the rise and fall times of the SiPM signal,which can significantly improve the time resolution and reduce the pile-up when using a large SiPM or an array of SiPMs.Various combinations of the preamplifier and several types of SiPMs demonstrated time resolutions better than 50 ps for most cases;when the number of detected photons was larger than 60,a time resolution of approximately 25 ps was achieved.展开更多
The transition from middle-income to high-income stage is fraught with risks of growth divergence. Economic transition is clouded by the following possibilities: (1)falling share of industrial seetor through indust...The transition from middle-income to high-income stage is fraught with risks of growth divergence. Economic transition is clouded by the following possibilities: (1)falling share of industrial seetor through industrial depression and weakening growth momentum caused by the large urbanization costs; (2) the subordination of service sector as a result of nearly irreversibly industrial professional, which falters the process of service sector transition and upgrading," (3) inefficient knowledge production allocation and human capital upgrade due to the absence of incentivized compensation of knowledge consumption. We suggest that a country should reshape its efficiency model by upgrading knowledge factor and human capital as the pre-requisite. Given the dilemmas of transition, China should take the faetorization trend of service sector and reshape efficiency model through institutional reform, ensuring that service sector will develop in tandem with industrial sector.展开更多
The combining site of OKT3 was modeled,and Human Ig LS1 and ND were selected asacceptors of CDRs of OKT3 VL and VH to construct a reshaping antibody against CD3.Bycomparing OKT3,LS1 and ND,with their own family sequen...The combining site of OKT3 was modeled,and Human Ig LS1 and ND were selected asacceptors of CDRs of OKT3 VL and VH to construct a reshaping antibody against CD3.Bycomparing OKT3,LS1 and ND,with their own family sequences,some residues werechanged and the reshaping VL and VH genes were designed.The full VH gene was assem-bled in three steps with eight chemically synthesized oligonucleotide fragments using over-lapping PCR and sequenced.The VH gene was expressed as active protein and inclusion bod-ies in the vectors of pCOMB3 and pGEX-4T-1 by ELISA and Western blot analysis.展开更多
Since the 18 th National Congress of the Communist Party of China,the central government has implemented several regional development plans,including the Belt and Road Initiative and the Yangtze River Economic Belt,ai...Since the 18 th National Congress of the Communist Party of China,the central government has implemented several regional development plans,including the Belt and Road Initiative and the Yangtze River Economic Belt,aiming to reshape the economic geography of China.This paper is based on the Belt and Road Initiative and the Yangtze River Economic Belt and outlines the pattern of opening up.To analyze the impact of the pattern of opening up on the regional integration of China's economic geography,this paper has developed a new economic geography model comprised of four regions and two countries.From this,it draws some conclusions.First,the change of pattern of opening up will lead to shifting centripetal and centrifugal forces from the international market.The greater the scale of neighboring markets,the stronger the agglomeration force will be; the more product varieties made in neighboring countries,the more potent its dispersion force.Second,developing an inland international trade corridor will decentralize industry distribution and reduce the impact of external market integration on home countries.Third,the inland international trade corridor could alter the effect of domestic market integration on the economic geography.When domestic integration occurs prior to international integration,further integration of a domestic market leads to greater industrial distribution along a bell-shaped curve,which describes economic activities from dispersion to agglomeration to decentralization.Therefore,developing an integrated market system of major countries and opening a corridor between China and Europe is not only the key to reshaping China's economic geography but also the path to solving the problems of the Heihe-Tengchong Line.展开更多
The global security situation in 2018 continued with its recent years of complexity and volatility,with its order and rules challenged by the prevailing unilateralism and trade protectionism,the emerging nationalism a...The global security situation in 2018 continued with its recent years of complexity and volatility,with its order and rules challenged by the prevailing unilateralism and trade protectionism,the emerging nationalism and populism,the resurgent power politics and authoritarianism,theintensified competition in geopolitical and other new areas,and the incessant regional turmoil and conflicts.展开更多
Impact of amplified spontaneous emission(ASE)noise on the stimulated Raman scattering(SRS)threshold of highpower fiber amplifiers is demonstrated numerically through a spectral evolution approach.The simulation result...Impact of amplified spontaneous emission(ASE)noise on the stimulated Raman scattering(SRS)threshold of highpower fiber amplifiers is demonstrated numerically through a spectral evolution approach.The simulation results confirm that ASE noise in the Raman wavelength band could reduce the SRS threshold of high-power fiber amplifiers significantly.As for ASE noise originated the main amplifier,it becomes stronger and reduces the SRS threshold at shorter operation wavelength below 1052 nm.As for ASE noise originated from the seed laser,it reduces the SRS threshold at different operation wavelength under the condition that the Raman ratio is over-90 dB in the seed laser.The theoretical method and results in this work could provide a well reference to extend the operation wavelength of high-power fiber lasers.展开更多
A hybrid linear amplifier is inserted at the output of the source-in-the-middle distribution protocol to overcome the shortcomings of the transmission distance.The modified protocol aims to maintain a high key rate fo...A hybrid linear amplifier is inserted at the output of the source-in-the-middle distribution protocol to overcome the shortcomings of the transmission distance.The modified protocol aims to maintain a high key rate for long-distance transmission under high noise.It has the potential to significantly broaden the application range of the continuous variable quantum key distribution protocol.The effects of amplifier parameters and noise on the modified protocol are analyzed in detail with regard to applying it to a practical system.To make the simulation more realistic,the effect of finite size on the new protocol is taken into account.It will serve as a guideline for the future use of hybrid linear amplifiers.Different parameters can be adjusted to achieve the best performance for key rates of different quantum channels.展开更多
基金financially supported by the National Natural Science Foundation of China (51674088)Natural Science Foundation of Heilongjiang Province of China (LH 2021E011)。
文摘Hydraulic rolling reshaper is an advanced reshaping tool to solve the problem of casing deformation,which has been widely used in recent years.When it is used for well repair operation,the reshaping force provided by ground devices is generally determined by experience.However,too large reshaping force may destroy the deformed casing,and too small reshaping force may also prolong the construction period and affect the repairing effect.In this paper,based on Hertz contact theory and elastic-plastic theory,combined with the process parameters of shaping,and considering the structural characteristics of the deformed casing and reshaper,we propose a mathematical model for calculating the reshaping force required for repairing deformed casing by hydraulic rolling reshaper.Meanwhile,the finite element model and numerical method of hydraulic rolling reshaper repairing deformed casing are established by using the finite element method,and the reliability of the mathematical model is verified by several examples.On this basis,the control variable method is used to investigate the influence of each parameter on the reshaping force,and the influence degree of each parameter is explored by orthogonal simulation test and Pearson correlation analysis.The research results not only provide an important theoretical basis for the prediction of reshaping force in on-site construction,but also provide a reference for the subsequent improvement of the shaping process.
基金phased result of“Feasibility Demonstration of Basic Legislation on Artificial Intelligence”(Project No.2022K20263)a project of the Bureau of Law-based Cyberspace Governance at the Cyberspace Administration of China。
文摘Whether a new generation of human rights emerges in the digital age has sparked widespread debate.Academic understanding of digital technology remains confined to thinking about network technology and products,often overlooking the revolutionary nature of digital media.Digital media has the sweeping potential to unify all forms of media and reshape social life,giving rise to new demands for a new generation of human rights.The concept of digital human rights can be defined as the legitimate rights of human's infinitely extended personalities through digital media.Its core characteristic is its transcendency,where every person lives in a networked space that surpasses physical boundaries,nations,and individual personalities.Human rights are generally considered the foundation for basic constitutional rights,which,in turn,form the basis for legislative acts across various sectors.In recent years,China has enacted numerous laws in the digital domain to keep pace with the times,but due to the lack of guidance on digital human rights,these laws tend to be fragmented and disjointed.It is urgent to unify digital legislation at all levels on the basis of reshaping basic constitutional rights.Thus,it is essential to reshape the basic rights based on the concept and characteristics of digital human rights and streamline legislation at all levels under the unified guidance of basic rights.This can help establish a comprehensive digital human rights protection system that meets the demands of the modern era.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10225417 and 61675009)the Natural Science Foundation of Beijing Municipality (Grant Nos. 4204091 and KZ201910005006)the China Postdoctoral Science Foundation (Grant No. 212423)。
文摘An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.
基金supported by National Natural Science Foundation of China(No.62001061)。
文摘In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency points can be characterized by a polynomial.And in the practical test,the coefficients of SSF can be determined by measuring a small number of data points of input power.Same as other dualinput DPAs,the proposed approach can also achieve high output power and back-off efficiency in a broadband operation band by adjusting the power distribution ratio flexibly.Finally,a 1.5-2.5 GHz highefficiency dual-input Doherty power amplifier is implemented according to this approach.The test results show that the peak power is 48.6-49.7d Bm,and the 6-d B back-off efficiency is 51.0-67.0%,and the saturation efficiency is 52.4-74.6%.The digital predistortion correction is carried out at the frequency points of 1.8/2.1GHz,and the adjacent channel power ratio is lower than-54.5d Bc.Simulation and experiment results can verify the effectiveness and correctness of the proposed method.
文摘Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.
基金supported in part by the National Key Research and Development Program of China(2021YFA0716601)the National Science Fund(62225111).
文摘In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)application.An inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small area.The proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 dBm.The gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 GHz.The measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.
基金support from the Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No.2019319)support from the Start-up Foundation of Suzhou Institute of Nano-Tech and Nano-Bionics,CAS,Suzhou (Grant No.Y9AAD110)。
文摘A Josephson traveling wave parametric amplifier(JTWPA),which is a quantum-limited amplifier with high gain and large bandwidth,is the core device of large-scale measurement and control systems for quantum computing.A typical JTWPA consists of thousands of Josephson junctions connected in series to form a transmission line and hundreds of shunt LC resonators periodically loaded along the line for phase matching.Because the variation of these capacitors and inductors can be detrimental to their high-frequency characteristics,the fabrication of a JTWPA typically necessitates precise processing equipment.To guide the fabrication process and further improve the design for manufacturability,it is necessary to understand how each electronic component affects the amplifier.In this paper,we use the harmonic balance method to conduct a comprehensive study on the impact of nonuniformity and fabrication yield of the electronic components on the performance of a JTWPA.The results provide insightful and scientific guidance for device design and fabrication processes.
文摘For time-of-flight(TOF)light detection and ranging(LiDAR),a three-channel high-performance transimpedance amplifier(TIA)with high immunity to input load capacitance is presented.A regulated cascade(RGC)as the input stage is at the core of the complementary metal oxide semiconductor(CMOS)circuit chip,giving it more immunity to input photodiode detectors.A simple smart output interface acting as a feedback structure,which is rarely found in other designs,reduces the chip size and power consumption simultaneously.The circuit is designed using a 0.5μm CMOS process technology to achieve low cost.The device delivers a 33.87 dB?transimpedance gain at 350 MHz.With a higher input load capacitance,it shows a-3 dB bandwidth of 461 MHz,indicating a better detector tolerance at the front end of the system.Under a 3.3 V supply voltage,the device consumes 5.2 mW,and the total chip area with three channels is 402.8×597.0μm2(including the test pads).
基金supported by the National Natural Science Foundation of China(61931015,62071335,62250024)the Natural Science Foundation of Hubei Province of China(2021CFA002)+1 种基金the Fundamental Research Funds for the Central Universities of China(2042022dx0001)the Science and Technology Program of Shenzhen(JCYJ20170818112037398).
文摘To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and communication(RadCom)systems is studied,the channel estimation in passive sensing scenarios.Adaptive channel estimation methods are proposed based on different pilot patterns,considering nonlinear distortion and channel sparsity.The proposed methods achieve sparse channel results by manipulating the least squares(LS)frequency-domain channel estimation results to preserve the most significant taps.The decision-aided method is used to optimize the sparse channel results to reduce the effect of nonlinear distortion.Numerical results show that the channel estimation performance of the proposed methods is better than that of the conventional methods under different pilot patterns.In addition,the bit error rate performance in communication and passive radar detection performance show that the proposed methods have good comprehensive performance.
基金the National Natural Science Foundation of China(Nos.11772293 and12072312)Zhejiang Science and Technology Project(No.2019C03129)。
文摘An actual ecological predator-prey system often undergoes random environmental mutations owing to the impact of natural disasters and man-made destruction, which may destroy the balance between the species. In this paper,the stochastic dynamics of the nonlinear predator-prey system considering random environmental mutations is investigated, and a feedback control strategy is proposed to reshape the response of the predator-prey system against random abrupt environmental mutations. A delayed Markov jump system(MJS) is established to model such a predator-prey system. A novel first integral is constructed which leads to better approximation solutions of the ecosystem. Then, by applying the stochastic averaging method based on this novel first integral, the stochastic response of the predator-prey system is investigated, and an analytical feedback control is designed to reshape the response of the ecosystem from the disturbed state back to the undisturbed one.Numerical simulations finally illustrate the accuracy and effectiveness of the proposed procedure.
基金Supported by the NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(No.U1809212)the Scientific and Technical Project of Zhejiang Province(Nos.2021C02055,2017C02013)+1 种基金the National Natural Science Foundation of China(No.31272642)the Healthy Aquaculture,the K.C.Wong Magna Fund in Ningbo University,and the Collaborative Innovation Center for Zhejiang Marine High-efficiency。
文摘The homodimeric kinesin-2 protein KIF17 functions in intracellular transport and spermiogenesis in mammals.However,its role in fish spermiogenesis has not been reported.Here,we aimed to clone full-length kif17 cDNA and determine the molecular characteristics and expression patterns of KIF17 in Larimichthys polyactis spermiogenesis.The full-length cDNA of L.polyactis kif17(Lp-kif17)was sequenced and found to contain a 332-bp 5′untranslated region,480-bp 3′untranslated region,and 2433-bp open reading frame encoding 810 amino acids.Bioinformatics analyses showed that L.polyactis KIF17(Lp-KIF17)shared high sequence similarity with homologs in other animals and possessed an N-terminal motor domain with microtubule-binding sites and adenosine triphosphate(ATP)hydrolysis sites,a stalk domain containing two coiled-coil regions,and a C-terminal tail domain.The Lp-kif17 mRNA was widely expressed in various tissues,with the highest level in the brain,followed by that in the testis.Fluorescence in situ hybridization(FISH)analysis revealed that Lp-kif17 was continuously expressed in spermiogenesis,showing that it had potential functions in this process.Using immunofluorescence(IF)analysis,we found that Lp-KIF17 colocalized with tubulin and was transferred from the perinuclear cytoplasm to the side of spermatid where the tail forms during spermiogenesis.These findings suggested that KIF17 is involved in L.polyactis spermiogenesis.In particular,it may participate in nuclear shaping and tail formation by interacting with perinuclear microtubules during spermatid reshaping.In addition to providing evidence for the role of KIF17 in fish spermatid reshaping,this study provides important data for studies of reproductive biology in L.polyactis.
基金supported by National Natural Science Foundations of China (No.61971052 and No.U20A20203)Key Research and Development Project of Guangdong Province (2020B0101080001)
文摘In this paper,a 5G wideband power amplifier(PA)with bandpass filtering response is synthesized using a bandwidth-extended bandpass filter as the matching network(MN).In this structure,the bandwidth(θ_(C))is defined as a variable in the closedform equations provided by the microstrip bandpass filter.It can be extended over a wide range only by changing the characteristic impedances of the structure.Different from the other wideband MNs,the extension of bandwidth does not increase the complexity of the structure(order n is fixed).In addition,based on the bandwidth-extended structure,the wideband design of bandpass filtering PA is not limited to the fixed bandwidth of the specific filter structure.The theoretical analysis of the MN and the design flow of the PA are provided in this design.The fabricated bandpass filtering PA can support almost one-octave bandwidth(2-3.8 GHz),covering the two 5G bands(n41 and n78).The drain efficiency of 47%-60%and output power higher than 40 dBm are measured.Good frequency selectivity in S-parameter measurements can be observed.
基金This work was partially supported by the National Key R&D Program of China(No.2022YFA1601903)the National Natural Science Foundation of China(Nos.11925502,11961141003,and 12175041)the Strategic Priority Research Program of the CAS(No.XDB34030000).
文摘Considering the R&D for upgrading the K^(0)_(L) andμdetectors in the Belle II experiment using a scintillator and silicon pho-tomultiplier(SiPM),we designed a compact high-speed and low-noise preamplifier.The preamplifier demonstrated a good gain stability,bandwidth of 426 MHz,baseline noise level ofσ≈0.6 mV,dynamic range of up to170 mV of the input signal amplitude,good time resolution of 20 ps,and it can be comprehensively applied to SiPMs.Adopting pole-zero-cancelation in the preamplifier reduces both the rise and fall times of the SiPM signal,which can significantly improve the time resolution and reduce the pile-up when using a large SiPM or an array of SiPMs.Various combinations of the preamplifier and several types of SiPMs demonstrated time resolutions better than 50 ps for most cases;when the number of detected photons was larger than 60,a time resolution of approximately 25 ps was achieved.
基金sponsored by major tendering projects of National Social Sciences Foundation "Study on Accelerating Economic Adjustment and Coordinated Development"(Grant No.12&ZD084) and "Study on Contribution of Consumption to Economic Growth under Shifting Demand Structure"(Grant No.15ZDC011)projects of National Social Sciences Foundation "Study on China's Structural Growth Deceleration,Transition Risks and Efficiency Improvement Path"(Grant No.14AJL006) and "Study on the Scale,Spatial Clustering and Management Model of Chinese Cities"(Grant No.15ZDC011)
文摘The transition from middle-income to high-income stage is fraught with risks of growth divergence. Economic transition is clouded by the following possibilities: (1)falling share of industrial seetor through industrial depression and weakening growth momentum caused by the large urbanization costs; (2) the subordination of service sector as a result of nearly irreversibly industrial professional, which falters the process of service sector transition and upgrading," (3) inefficient knowledge production allocation and human capital upgrade due to the absence of incentivized compensation of knowledge consumption. We suggest that a country should reshape its efficiency model by upgrading knowledge factor and human capital as the pre-requisite. Given the dilemmas of transition, China should take the faetorization trend of service sector and reshape efficiency model through institutional reform, ensuring that service sector will develop in tandem with industrial sector.
基金Supported by National Natural Science Foundation of Chinathe High Technology Research and Development Programme of China.
文摘The combining site of OKT3 was modeled,and Human Ig LS1 and ND were selected asacceptors of CDRs of OKT3 VL and VH to construct a reshaping antibody against CD3.Bycomparing OKT3,LS1 and ND,with their own family sequences,some residues werechanged and the reshaping VL and VH genes were designed.The full VH gene was assem-bled in three steps with eight chemically synthesized oligonucleotide fragments using over-lapping PCR and sequenced.The VH gene was expressed as active protein and inclusion bod-ies in the vectors of pCOMB3 and pGEX-4T-1 by ELISA and Western blot analysis.
基金a staged research result of "Studies on New Strategic Regions Contributing to China’s Economic Growth in the Future"(14ZDA024)a major program of the National Social Science Fund of China+3 种基金"Studies on Regional Integration and Welfare Compensation on the Basis of Dynamic CGE and DCI Models"(71173101)a program funded by the National Natural Science Foundation of China"Studies on Path and Mechanism to Improve Economic Performance and Quality in Jiangsu Province from the Perspective of the Supply Side"(BRA2017358)a Jiangsu "333" High-level Cultivation Program
文摘Since the 18 th National Congress of the Communist Party of China,the central government has implemented several regional development plans,including the Belt and Road Initiative and the Yangtze River Economic Belt,aiming to reshape the economic geography of China.This paper is based on the Belt and Road Initiative and the Yangtze River Economic Belt and outlines the pattern of opening up.To analyze the impact of the pattern of opening up on the regional integration of China's economic geography,this paper has developed a new economic geography model comprised of four regions and two countries.From this,it draws some conclusions.First,the change of pattern of opening up will lead to shifting centripetal and centrifugal forces from the international market.The greater the scale of neighboring markets,the stronger the agglomeration force will be; the more product varieties made in neighboring countries,the more potent its dispersion force.Second,developing an inland international trade corridor will decentralize industry distribution and reduce the impact of external market integration on home countries.Third,the inland international trade corridor could alter the effect of domestic market integration on the economic geography.When domestic integration occurs prior to international integration,further integration of a domestic market leads to greater industrial distribution along a bell-shaped curve,which describes economic activities from dispersion to agglomeration to decentralization.Therefore,developing an integrated market system of major countries and opening a corridor between China and Europe is not only the key to reshaping China's economic geography but also the path to solving the problems of the Heihe-Tengchong Line.
文摘The global security situation in 2018 continued with its recent years of complexity and volatility,with its order and rules challenged by the prevailing unilateralism and trade protectionism,the emerging nationalism and populism,the resurgent power politics and authoritarianism,theintensified competition in geopolitical and other new areas,and the incessant regional turmoil and conflicts.
基金the National Natural Science Foundation of China(Grant Nos.62005313 and 62061136013).
文摘Impact of amplified spontaneous emission(ASE)noise on the stimulated Raman scattering(SRS)threshold of highpower fiber amplifiers is demonstrated numerically through a spectral evolution approach.The simulation results confirm that ASE noise in the Raman wavelength band could reduce the SRS threshold of high-power fiber amplifiers significantly.As for ASE noise originated the main amplifier,it becomes stronger and reduces the SRS threshold at shorter operation wavelength below 1052 nm.As for ASE noise originated from the seed laser,it reduces the SRS threshold at different operation wavelength under the condition that the Raman ratio is over-90 dB in the seed laser.The theoretical method and results in this work could provide a well reference to extend the operation wavelength of high-power fiber lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.62201620)the Outstanding Youth Program of Education Department of Hunan(Grant No.21B0228)+2 种基金Changsha Municipal Natural Science Foundation(Grant No.kq2202293)Hunan Students’Platform for innovation and entrepreneurship training program(Grant No.S202210538069)the Research Fund of Central South University of Forestry and Technology(Grant No.1121001703).
文摘A hybrid linear amplifier is inserted at the output of the source-in-the-middle distribution protocol to overcome the shortcomings of the transmission distance.The modified protocol aims to maintain a high key rate for long-distance transmission under high noise.It has the potential to significantly broaden the application range of the continuous variable quantum key distribution protocol.The effects of amplifier parameters and noise on the modified protocol are analyzed in detail with regard to applying it to a practical system.To make the simulation more realistic,the effect of finite size on the new protocol is taken into account.It will serve as a guideline for the future use of hybrid linear amplifiers.Different parameters can be adjusted to achieve the best performance for key rates of different quantum channels.