Sputum smear tests are critical for the diagnosis of respiratory diseases. Automatic segmentation of bacteria from spu-tum smear images is important for improving diagnostic efficiency. However, this remains a challen...Sputum smear tests are critical for the diagnosis of respiratory diseases. Automatic segmentation of bacteria from spu-tum smear images is important for improving diagnostic efficiency. However, this remains a challenging task owing to the high interclass similarity among different categories of bacteria and the low contrast of the bacterial edges. To explore more levels of global pattern features to promote the distinguishing ability of bacterial categories and main-tain sufficient local fine-grained features to ensure accurate localization of ambiguous bacteria simultaneously, we propose a novel dual-branch deformable cross-attention fusion network (DB-DCAFN) for accurate bacterial segmen-tation. Specifically, we first designed a dual-branch encoder consisting of multiple convolution and transformer blocks in parallel to simultaneously extract multilevel local and global features. We then designed a sparse and deformable cross-attention module to capture the semantic dependencies between local and global features, which can bridge the semantic gap and fuse features effectively. Furthermore, we designed a feature assignment fusion module to enhance meaningful features using an adaptive feature weighting strategy to obtain more accurate segmentation. We conducted extensive experiments to evaluate the effectiveness of DB-DCAFN on a clinical dataset comprising three bacterial categories: Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The experi-mental results demonstrate that the proposed DB-DCAFN outperforms other state-of-the-art methods and is effective at segmenting bacteria from sputum smear images.展开更多
Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the ac...Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.展开更多
The focal mechanism solutions of the MS. 1 Badong earthquake and subsequent 34 aftershocks at ML 2.0 or more were calculated using the P-wave first motion method; the main earthquake was normal fault dip slip type, an...The focal mechanism solutions of the MS. 1 Badong earthquake and subsequent 34 aftershocks at ML 2.0 or more were calculated using the P-wave first motion method; the main earthquake was normal fault dip slip type, and the slip types of the seismogenic rupture surfaces of the subsequent aftershocks primarily include normal dip slip （14 times）, reverse dip slip （9 times）, normal strike slip （9 times） and reverse strike slip （2 times）. The MS. 1 Badong earthquake activities may be related to the stress adjustment caused by the rise of the groundwater level and the decrease of the frictional resistance between structural planes of rock forma- tions due to the effect of reservoir water penetration, and related to the joint activities of the NE-strike Gaoqiao fault and the near EW-strike Daping fault.展开更多
Geothermal anomaly as a physical phenomenon of an active and latent volca nic area would be well recog-nized,and abrupt geothermal anomaly should also be understood.However,in practical work,thermal infrare d remote s...Geothermal anomaly as a physical phenomenon of an active and latent volca nic area would be well recog-nized,and abrupt geothermal anomaly should also be understood.However,in practical work,thermal infrare d remote sensing techniques are frequently u sed to monitor geothermal flows of th e earth.But then,except for this typ e of thermal source in the surface thermal field,there still exist a lot of noises in th e area where the abrupt geothermal an omaly is generat-ed.By Analyzing the reason,we find t hat it is brought about by the non-bou ndless projection characteristics of objects.These noises may be divided into two c lasses:system noises and random noises.If disturbed noises have comparative sta-ble time sequence law and space sequence law,the noises are called system noises.And because system noises have a certain law,it is easy to remove the n oises.On the contrary,if disturbed noises have not law of time sequence a nd space sequence,the noises are called random noises.The random noises have the character of non-linearity,uncertainty and indeterminism.For this case,this p aper discusses the disturbed mechan ism of these noises as well as how to re move them..展开更多
Rapidly quenching embrittlement (RQE) sometimes appears in nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mech...Rapidly quenching embrittlement (RQE) sometimes appears in nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mechanism of RQE has been elucidated in the recent works of current authors. R was believed that RQE is due to the structural relaxation but not related to α-Fe(Si) crystallization. In this paper, the high resolution TEM (HRTEM) method and image digital processing were applied to analyze the HRTEM images of two FINEMET rapidly quenched ribbons with different thicknesses in detail. In the thinner ductile sample, the ordering domains with the size of about 3nm are observed. In the thicker RQE sample, the metastable nanocrystalline domains with the size of 18nm are observed along with the structural relaxation. These domains seem to have Fe3B-like metastable phase struc-ture on nanometer scale. The result indicates that the local atomic ordering regions extend when RQE induced by structural relaxation occurs.展开更多
The thermal decomposition processes of（MgCO3）4·Mg（OH）2·5H2O（MCH）,5ZnO·2CO3·4H2O（ZCH）,NiCO3·2Ni（OH）2·4H2O（NCH）,PbCO3（LC）and [Cr（OH）5]2·CO3·8H2O（CC）were studied ...The thermal decomposition processes of（MgCO3）4·Mg（OH）2·5H2O（MCH）,5ZnO·2CO3·4H2O（ZCH）,NiCO3·2Ni（OH）2·4H2O（NCH）,PbCO3（LC）and [Cr（OH）5]2·CO3·8H2O（CC）were studied via TG-DSC.The results of research imply that MCH has the largest capacity of heat absorption and ZCH is second to MCH among the studied materials.The non-isothermal kinetic parameters of MCH and ZCH were calculated by Kissinger and Ozawa methods.Furthermore,thermal decomposition mechanisms of MCH and ZCH were investigated by Coats-Redfern method.Due to the large specific heat capacity,MCH and ZCH are promising to be used as a coolant in extinguishant formulations.展开更多
Oxidative stress is a major factor affecting animal health and production performance. This paper briefly introduced the signaling pathways(i.e. NF-κB signaling pathway, MAPK, AP-1 and PGC-1α) of oxidative stress an...Oxidative stress is a major factor affecting animal health and production performance. This paper briefly introduced the signaling pathways(i.e. NF-κB signaling pathway, MAPK, AP-1 and PGC-1α) of oxidative stress and the main genes regulating the signals of oxidative stress in skeletal muscle, providing a theoretical basis for reducing oxidative stress damage.展开更多
We collect a sample of 51 Fermi-detected gamma-ray loud blazars with known radio Doppler factors and study properties of the Doppler factors of blazars at optical, X-ray and gamma-ray bands. A basic assumption is that...We collect a sample of 51 Fermi-detected gamma-ray loud blazars with known radio Doppler factors and study properties of the Doppler factors of blazars at optical, X-ray and gamma-ray bands. A basic assumption is that the emission from the radio to gamma-ray bands of the blazars are produced by the nonthermal radiation of accelerated particles in a jet. Our results show that （1） the Doppler factors of blazars are a function of frequency, with the Doppler factor decreasing with frequency from the radio to X-ray regions, and then increasing from the X-ray to ,y-ray regions which are similar to results given by Zhang et al., and （2） there are marginal correlations between the Doppler factors at radio and X-ray bands and the synchrotron peak fre- quency, and a strong correlation between the Doppler factor in the gamma-ray band and the synchrotron peak frequency, but no correlation in the optical band.展开更多
In this work, we had adopted solid states reaction kinetic model to calculate diffusion coefficient of graphite Gr in Gum Arabic (GA) as the function of temperatures and concentration? D(t, C). From the calculations w...In this work, we had adopted solid states reaction kinetic model to calculate diffusion coefficient of graphite Gr in Gum Arabic (GA) as the function of temperatures and concentration? D(t, C). From the calculations we have found that the diffusion coefficient D increases with increasing temperature. At higher temperature the Gr atoms might get enough thermal energy to overcome the activation energy (Ea) barrier and hence can easily be transported to a new atomic position. Diffusion coefficient of Gr at high concentrations had exceeded that at low concentrations by more than two to three orders of magnitude. Such increase can be attributed to the large number of jumps or jump frequency which found to be directly proportion to the Gr concentration. Electric conductivity, calculated by Nernst-Einstein equation, at high concentration Gr had exceeded that at lower concentration. The decrease in conductivity with decreasing Gr concentration might be attributed to the effective charges interactions, which lead to enhance the recombination of charge carriers.展开更多
Synthesis of terpolymers consisting of two electron-donating monomers, viz. styrene and vinyl acetate with one electron-accepting monomer, i.e. acrylonitrile, initiated by p-nitrobenzyl triphenyl phosphonim ylide in d...Synthesis of terpolymers consisting of two electron-donating monomers, viz. styrene and vinyl acetate with one electron-accepting monomer, i.e. acrylonitrile, initiated by p-nitrobenzyl triphenyl phosphonim ylide in dioxane as diluent at 65°C for 150 min has been studied. The kinetic expression is Rpα[I]0.8[Sty] 1.2[VA] 1.4 [AN]1.2. The terpolymer composition was determined by the Kelen-Tüdos method. The values of reactivity ratios using r1 (Sty + VA) = 0.1 and r2 (AN) = 0.005. The overall activation energy is 46 kJ●mol●L–1. The formation of terpolymer is confirmed by the FTIR spectra showing bands at 3030 cm–1, 1598 cm–1, and 2362 cm–1, confirming the presence of phenyl, acetoxy and nitrile group respectively. The terpolymer has been characterized by 1H-Nuclear Magnetic Resonance, 13C-Nuclear Magnetic Resonance. The Differential Scanning Calorimetric curve shows the Tg of the polymer as 149.5°C. A scanning electron microscope confirms the polymer to be phosphorus free. Electron.Spin.Resonance spectra confirms phenyl radical responsible for initiation.展开更多
In the one-bit massive multiple-input multiple-output(MIMO)channel scenario,the accurate channel estimation becomes more difficult because the signals received by the low-resolution analog-to-digital converters(ADC)ar...In the one-bit massive multiple-input multiple-output(MIMO)channel scenario,the accurate channel estimation becomes more difficult because the signals received by the low-resolution analog-to-digital converters(ADC)are quantized and affected by channel noise.Therefore,a one-bit massive MIMO channel estimation method is proposed in this paper.The channel matrix is regarded as a two-dimensional image.In order to enhance the significance of noise features in the image and remove them,the channel attention mechanism is introduced into the conditional generative adversarial network(CGAN)to generate channel images,and im-prove the loss function.The simulation results show that the improved network can use a smaller number of pilots to obtain better channel estimation results.Under the same number of pilots and signal-to-noise ratio(SNR),the channel estimation accuracy can be improved by about 7.5 dB,and can adapt to the scenarios with more antennas.展开更多
The electrochemical reaction mechanism and electrocrystallization process of Cu on copper electrode in the eutectic NaC1-KC1-CuC1 molten salt were investigated by means of cyclic voltammetry, chronopotentiometry and c...The electrochemical reaction mechanism and electrocrystallization process of Cu on copper electrode in the eutectic NaC1-KC1-CuC1 molten salt were investigated by means of cyclic voltammetry, chronopotentiometry and chronoamperometry tech-nique at 710℃. The results show that the electrochemical reaction process of Cu is a quasi-reversible process mix-controlled by Cu＋ diffusion rate and electron transport rate;the electrochemical reduction mechanism is Cu＋e→Cu;the electrocrystallization process of copper is an instantaneous hemispheroid three-dimensional nucleation process; the Cu diffusino coefficient is 4.3×10^-4cm^2·s^-1 under the experimental conditions.展开更多
The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in...The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive factors that could not be neglected in cutting at such a scale. In the present study, the crystallographic orientation effect on the cutting-based single atomic layer removal of monocrystalline copper is investigated by molecular dynamics simulation. When undeformed chip thickness is in the atomic scale, two kinds of single atomic layer removal mechanisms exist in cutting-based single atomic layer removal, namely, dislocation motion and extrusion, due to the differing atomic structures on different crystallographic planes. On close-packed crystallographic plane, the material removal is dominated by the shear stress-driven dislocation motion, whereas on non-close packed crystallographic planes, extrusion-dominated material removal dominates. To obtain an atomic, defect-free processed surface, the cutting needs to be conducted on the close-packed crystallographic planes of monocrystalline copper.展开更多
The mechanism of the femtosecond laser ablation of semiconductors is investigated. The collision pro cess of free electrons in a conduction band is depicted by the test particle method, and a theoretical model of none...The mechanism of the femtosecond laser ablation of semiconductors is investigated. The collision pro cess of free electrons in a conduction band is depicted by the test particle method, and a theoretical model of nonequilibrium electron transport on the femtosecond timescale is proposed based on the FokkerPlanck equa tion. This model considers the impact of inverse bremsstrahlung on the laser absorption coefficient, and gives the expressions of electron drift and diffusion coefficients in the presence of screened Coulomb potential. Numerical simulations are conducted to obtain the nonequilibrium distribution function of the electrons. The femtosecond laser ablation thresholds are then calculated accordingly, and the results are in good agreement with the experimental results. This is followed by a discussion on the impact of laser parameters on the ablation of semiconductors.展开更多
We used ABEEMon（atom-bond electronegativity equalization method） polarizable force field（ABEEMσπ PFF） method combined with QM and molecular dynamics-free energy perturbation（MD-FEP） methods to investigatethe f...We used ABEEMon（atom-bond electronegativity equalization method） polarizable force field（ABEEMσπ PFF） method combined with QM and molecular dynamics-free energy perturbation（MD-FEP） methods to investigatethe function of water molecules in hydrolysis process of ImH[trans-Ru（Im）2Cl4]（ICR）. The activation free energiesobtained via MD-FEP calculation are in fair agreement with the experimental data. In addition, QM/MM（ABEEM）rationally describes the charge distributions and the electrostatic interaction between molecules. ABEEMσπ fluctua-ting charge model has the following good characteristics： （1） not only atomic charge regions but also σ,π bond andlone pair charge regions are explicitly represented for a molecule; （2） the region charges are geometry dependent andcalculated from time to time in the dynamic simulation without any iterative procedure so that its performance istime-saving compared with the Drude model and induced dipole model.展开更多
基金the Natural Science Foundation of Shandong Province,No.ZR2021MH213and in part by the Suzhou Science and Technology Bureau,No.SJC2021023.
文摘Sputum smear tests are critical for the diagnosis of respiratory diseases. Automatic segmentation of bacteria from spu-tum smear images is important for improving diagnostic efficiency. However, this remains a challenging task owing to the high interclass similarity among different categories of bacteria and the low contrast of the bacterial edges. To explore more levels of global pattern features to promote the distinguishing ability of bacterial categories and main-tain sufficient local fine-grained features to ensure accurate localization of ambiguous bacteria simultaneously, we propose a novel dual-branch deformable cross-attention fusion network (DB-DCAFN) for accurate bacterial segmen-tation. Specifically, we first designed a dual-branch encoder consisting of multiple convolution and transformer blocks in parallel to simultaneously extract multilevel local and global features. We then designed a sparse and deformable cross-attention module to capture the semantic dependencies between local and global features, which can bridge the semantic gap and fuse features effectively. Furthermore, we designed a feature assignment fusion module to enhance meaningful features using an adaptive feature weighting strategy to obtain more accurate segmentation. We conducted extensive experiments to evaluate the effectiveness of DB-DCAFN on a clinical dataset comprising three bacterial categories: Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The experi-mental results demonstrate that the proposed DB-DCAFN outperforms other state-of-the-art methods and is effective at segmenting bacteria from sputum smear images.
基金National Natural Science Foundation of China(Nos.51204147,51274175,51574206,51574207)Program for International S&T Cooperation Projects of China(No.2014DFA50320)+1 种基金Program for International S&T Cooperation Projects of Shanxi Province(No.201381017)Technological Projects of Shanxi Province(No.20150313002-3)
文摘Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.
基金supported by the Director Foundation of the Institute of Seismology,China Earthquake Adminstration(IS201246114)the Special Fund of China Three Gorges Corporation(SXSN/3354)
文摘The focal mechanism solutions of the MS. 1 Badong earthquake and subsequent 34 aftershocks at ML 2.0 or more were calculated using the P-wave first motion method; the main earthquake was normal fault dip slip type, and the slip types of the seismogenic rupture surfaces of the subsequent aftershocks primarily include normal dip slip （14 times）, reverse dip slip （9 times）, normal strike slip （9 times） and reverse strike slip （2 times）. The MS. 1 Badong earthquake activities may be related to the stress adjustment caused by the rise of the groundwater level and the decrease of the frictional resistance between structural planes of rock forma- tions due to the effect of reservoir water penetration, and related to the joint activities of the NE-strike Gaoqiao fault and the near EW-strike Daping fault.
文摘Geothermal anomaly as a physical phenomenon of an active and latent volca nic area would be well recog-nized,and abrupt geothermal anomaly should also be understood.However,in practical work,thermal infrare d remote sensing techniques are frequently u sed to monitor geothermal flows of th e earth.But then,except for this typ e of thermal source in the surface thermal field,there still exist a lot of noises in th e area where the abrupt geothermal an omaly is generat-ed.By Analyzing the reason,we find t hat it is brought about by the non-bou ndless projection characteristics of objects.These noises may be divided into two c lasses:system noises and random noises.If disturbed noises have comparative sta-ble time sequence law and space sequence law,the noises are called system noises.And because system noises have a certain law,it is easy to remove the n oises.On the contrary,if disturbed noises have not law of time sequence a nd space sequence,the noises are called random noises.The random noises have the character of non-linearity,uncertainty and indeterminism.For this case,this p aper discusses the disturbed mechan ism of these noises as well as how to re move them..
基金This work was supported by Chinese National Engineering Technology Research Center on Amorphous and Microcrystalline Alloys.
文摘Rapidly quenching embrittlement (RQE) sometimes appears in nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mechanism of RQE has been elucidated in the recent works of current authors. R was believed that RQE is due to the structural relaxation but not related to α-Fe(Si) crystallization. In this paper, the high resolution TEM (HRTEM) method and image digital processing were applied to analyze the HRTEM images of two FINEMET rapidly quenched ribbons with different thicknesses in detail. In the thinner ductile sample, the ordering domains with the size of about 3nm are observed. In the thicker RQE sample, the metastable nanocrystalline domains with the size of 18nm are observed along with the structural relaxation. These domains seem to have Fe3B-like metastable phase struc-ture on nanometer scale. The result indicates that the local atomic ordering regions extend when RQE induced by structural relaxation occurs.
基金Supported by the Basic Research Foundation of Beijing Institute of Technology(20130242017)the Project Foundation of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)(YBKT16-09)
文摘The thermal decomposition processes of（MgCO3）4·Mg（OH）2·5H2O（MCH）,5ZnO·2CO3·4H2O（ZCH）,NiCO3·2Ni（OH）2·4H2O（NCH）,PbCO3（LC）and [Cr（OH）5]2·CO3·8H2O（CC）were studied via TG-DSC.The results of research imply that MCH has the largest capacity of heat absorption and ZCH is second to MCH among the studied materials.The non-isothermal kinetic parameters of MCH and ZCH were calculated by Kissinger and Ozawa methods.Furthermore,thermal decomposition mechanisms of MCH and ZCH were investigated by Coats-Redfern method.Due to the large specific heat capacity,MCH and ZCH are promising to be used as a coolant in extinguishant formulations.
基金Supported by Key Project of Natural Science Foundation of Hubei Province(2013CFA100)National Natural Science Foundation of China(31472117)
文摘Oxidative stress is a major factor affecting animal health and production performance. This paper briefly introduced the signaling pathways(i.e. NF-κB signaling pathway, MAPK, AP-1 and PGC-1α) of oxidative stress and the main genes regulating the signals of oxidative stress in skeletal muscle, providing a theoretical basis for reducing oxidative stress damage.
文摘We collect a sample of 51 Fermi-detected gamma-ray loud blazars with known radio Doppler factors and study properties of the Doppler factors of blazars at optical, X-ray and gamma-ray bands. A basic assumption is that the emission from the radio to gamma-ray bands of the blazars are produced by the nonthermal radiation of accelerated particles in a jet. Our results show that （1） the Doppler factors of blazars are a function of frequency, with the Doppler factor decreasing with frequency from the radio to X-ray regions, and then increasing from the X-ray to ,y-ray regions which are similar to results given by Zhang et al., and （2） there are marginal correlations between the Doppler factors at radio and X-ray bands and the synchrotron peak fre- quency, and a strong correlation between the Doppler factor in the gamma-ray band and the synchrotron peak frequency, but no correlation in the optical band.
文摘In this work, we had adopted solid states reaction kinetic model to calculate diffusion coefficient of graphite Gr in Gum Arabic (GA) as the function of temperatures and concentration? D(t, C). From the calculations we have found that the diffusion coefficient D increases with increasing temperature. At higher temperature the Gr atoms might get enough thermal energy to overcome the activation energy (Ea) barrier and hence can easily be transported to a new atomic position. Diffusion coefficient of Gr at high concentrations had exceeded that at low concentrations by more than two to three orders of magnitude. Such increase can be attributed to the large number of jumps or jump frequency which found to be directly proportion to the Gr concentration. Electric conductivity, calculated by Nernst-Einstein equation, at high concentration Gr had exceeded that at lower concentration. The decrease in conductivity with decreasing Gr concentration might be attributed to the effective charges interactions, which lead to enhance the recombination of charge carriers.
文摘Synthesis of terpolymers consisting of two electron-donating monomers, viz. styrene and vinyl acetate with one electron-accepting monomer, i.e. acrylonitrile, initiated by p-nitrobenzyl triphenyl phosphonim ylide in dioxane as diluent at 65°C for 150 min has been studied. The kinetic expression is Rpα[I]0.8[Sty] 1.2[VA] 1.4 [AN]1.2. The terpolymer composition was determined by the Kelen-Tüdos method. The values of reactivity ratios using r1 (Sty + VA) = 0.1 and r2 (AN) = 0.005. The overall activation energy is 46 kJ●mol●L–1. The formation of terpolymer is confirmed by the FTIR spectra showing bands at 3030 cm–1, 1598 cm–1, and 2362 cm–1, confirming the presence of phenyl, acetoxy and nitrile group respectively. The terpolymer has been characterized by 1H-Nuclear Magnetic Resonance, 13C-Nuclear Magnetic Resonance. The Differential Scanning Calorimetric curve shows the Tg of the polymer as 149.5°C. A scanning electron microscope confirms the polymer to be phosphorus free. Electron.Spin.Resonance spectra confirms phenyl radical responsible for initiation.
基金National Key Re-search and Development Program of China(2017YFE0135700)High Level Talent Support Project of Hebei Province(A201903011)Natural Science Foundation of Hebei Province(F2018209358)。
文摘In the one-bit massive multiple-input multiple-output(MIMO)channel scenario,the accurate channel estimation becomes more difficult because the signals received by the low-resolution analog-to-digital converters(ADC)are quantized and affected by channel noise.Therefore,a one-bit massive MIMO channel estimation method is proposed in this paper.The channel matrix is regarded as a two-dimensional image.In order to enhance the significance of noise features in the image and remove them,the channel attention mechanism is introduced into the conditional generative adversarial network(CGAN)to generate channel images,and im-prove the loss function.The simulation results show that the improved network can use a smaller number of pilots to obtain better channel estimation results.Under the same number of pilots and signal-to-noise ratio(SNR),the channel estimation accuracy can be improved by about 7.5 dB,and can adapt to the scenarios with more antennas.
基金supported by the National Natural Science Foundation of China (No.51074060)
文摘The electrochemical reaction mechanism and electrocrystallization process of Cu on copper electrode in the eutectic NaC1-KC1-CuC1 molten salt were investigated by means of cyclic voltammetry, chronopotentiometry and chronoamperometry tech-nique at 710℃. The results show that the electrochemical reaction process of Cu is a quasi-reversible process mix-controlled by Cu＋ diffusion rate and electron transport rate;the electrochemical reduction mechanism is Cu＋e→Cu;the electrocrystallization process of copper is an instantaneous hemispheroid three-dimensional nucleation process; the Cu diffusino coefficient is 4.3×10^-4cm^2·s^-1 under the experimental conditions.
基金The authors would like to thank the finical support from the Science Foundation Ireland(Grant No.15/RP/B3208)the‘111’Project by the State Administration of Foreign Experts Affairs and the Ministry of Education of China(Grant No.B07014).
文摘The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive factors that could not be neglected in cutting at such a scale. In the present study, the crystallographic orientation effect on the cutting-based single atomic layer removal of monocrystalline copper is investigated by molecular dynamics simulation. When undeformed chip thickness is in the atomic scale, two kinds of single atomic layer removal mechanisms exist in cutting-based single atomic layer removal, namely, dislocation motion and extrusion, due to the differing atomic structures on different crystallographic planes. On close-packed crystallographic plane, the material removal is dominated by the shear stress-driven dislocation motion, whereas on non-close packed crystallographic planes, extrusion-dominated material removal dominates. To obtain an atomic, defect-free processed surface, the cutting needs to be conducted on the close-packed crystallographic planes of monocrystalline copper.
文摘The mechanism of the femtosecond laser ablation of semiconductors is investigated. The collision pro cess of free electrons in a conduction band is depicted by the test particle method, and a theoretical model of nonequilibrium electron transport on the femtosecond timescale is proposed based on the FokkerPlanck equa tion. This model considers the impact of inverse bremsstrahlung on the laser absorption coefficient, and gives the expressions of electron drift and diffusion coefficients in the presence of screened Coulomb potential. Numerical simulations are conducted to obtain the nonequilibrium distribution function of the electrons. The femtosecond laser ablation thresholds are then calculated accordingly, and the results are in good agreement with the experimental results. This is followed by a discussion on the impact of laser parameters on the ablation of semiconductors.
文摘We used ABEEMon（atom-bond electronegativity equalization method） polarizable force field（ABEEMσπ PFF） method combined with QM and molecular dynamics-free energy perturbation（MD-FEP） methods to investigatethe function of water molecules in hydrolysis process of ImH[trans-Ru（Im）2Cl4]（ICR）. The activation free energiesobtained via MD-FEP calculation are in fair agreement with the experimental data. In addition, QM/MM（ABEEM）rationally describes the charge distributions and the electrostatic interaction between molecules. ABEEMσπ fluctua-ting charge model has the following good characteristics： （1） not only atomic charge regions but also σ,π bond andlone pair charge regions are explicitly represented for a molecule; （2） the region charges are geometry dependent andcalculated from time to time in the dynamic simulation without any iterative procedure so that its performance istime-saving compared with the Drude model and induced dipole model.
