This paper presents a method for obtaining the displacement of sand particles in a sand–bentonite mixture(SBM)when saturated with water,based on particle tracking velocimetry(PTV).The raw photographs were first conve...This paper presents a method for obtaining the displacement of sand particles in a sand–bentonite mixture(SBM)when saturated with water,based on particle tracking velocimetry(PTV).The raw photographs were first converted into binary images.The sand particles were then detected,and the displacement of the sand particles was obtained by comparing their positions in adjacent images.The swelling strain induced by saturation was also obtained using the proposed PTV method.This method was validated by comparing the result with those obtained using a displacement transducer.Subsequently,a comparative analysis of sand particle displacements was conducted for specimens with varying bentonite content(BC),initial thickness,and water infiltration directions.The experimental results obtained were as follows:(1)For specimens with different BCs,local swelling displacement of sand particles at the top part of the specimen increased with higher BCs;(2)For specimens with various heights(hsp),larger local swelling displacement was generated at lower hsp at the initial state;(3)Local swelling characteristics differed in different water infiltration directions.Top-side infiltration showed a significant downward movement of particles during the first several hours of swelling.An estimation method for the dry density distribution of the specimen was proposed based on PTV data and then verified by slicing dry density and water content measurement results.展开更多
In this paper, a process modeling and related optimizing control for nonuniformly sampled （NUS） systems are addressed. By using a proposed nonuniform integration filter and subspace method estimation, an identificat...In this paper, a process modeling and related optimizing control for nonuniformly sampled （NUS） systems are addressed. By using a proposed nonuniform integration filter and subspace method estimation, an identification method of NUS systems is developed, based on which either an output soft sensor or a hidden state estimator is developed. The optimizing control is implemented by replacing the sparsely-mea- sured/immeasurable variable with the estimated one. Examples of optimizing control problem are given. The proposed optimizing control strategy in the simulation examples is verified to be very effeetive.展开更多
The deformation characteristics of tailor rolled blank （TRB） in the course of uniaxial tension were studied by means of analysis, test and simulation. The mechanical analytical model of TRB during uniaxial tension w...The deformation characteristics of tailor rolled blank （TRB） in the course of uniaxial tension were studied by means of analysis, test and simulation. The mechanical analytical model of TRB during uniaxial tension was set up, and the deformation formulae for the thinner side and for the thicker side were derived to quantify the deformation of TRB. On this basis, uniaxial tension tests on TRB and ordinary blanks （the thinner side and the thicker side of TRB） were conducted. Lagrange polynomial interpolation method was adopted to construct the stress-strain fields of unannealed and annealed TRBs for solving TRB material parameters, and then, uniaxial tension simulation on TRB was completed. Deformations and properties of unannealed TRB were compared with those of annealed TRB, and the thinner side and the thicker side were also compared. Finally, the research results were explained by metallurgical structure. The results show that nonuniform deformation happens in TRB during uniaxial tension, and the necking occurs on the thinner side. The agreement of analysis, test and simulation confirms the correctness of the analytical model and the deformation formulae. The findings of this paper can lay the foundation for the future study on TRB stamping formability and provide a way for TRB modeling.展开更多
Based on ensemble experiments with three atmospheric general circulation models(AGCMs), this study investigates the role of the Atlantic Multidecadal Oscillation(AMO) in shaping the summer nonuniform warming over the ...Based on ensemble experiments with three atmospheric general circulation models(AGCMs), this study investigates the role of the Atlantic Multidecadal Oscillation(AMO) in shaping the summer nonuniform warming over the Eurasian continent since the mid-1990 s. The results validate that the positive-phase AMO can indeed cause nonuniform warming,with predominant amplified warming over Europe–West Asia and Northeast Asia, but with much weaker warming over Central Asia. The underlying mechanism is then diagnosed from the perspective that the boundary forcing modulates the intrinsic atmospheric variability. The results highlight the role of the Silk Road Pattern(SRP), an intrinsic teleconnection pattern across the subtropical Eurasian continent propagating along the Asian jet. The SRP can not only be identified from the AGCM control experiments with the climatological sea surface temperature(SST), but can also be simulated by the AMO-related SST anomaly(SSTA) forcing. Furthermore, diagnostic linear baroclinic model experiments are conducted, and the results suggest that the SRP can be triggered by the AMO-related tropical diabatic heating. The AMO-triggered SRP-like responses feature anticyclonic circulations over Europe–West Asia and Northeast Asia, but cyclonic circulation over Central Asia. These responses cause increased warm advection towards Europe–West Asia and Northeast Asia, reduced precipitation and cloud cover, and then increased downward shortwave radiation. This increased warm advection and increased downward shortwave radiation together cause amplified warming in Europe–West Asia and Northeast Asia. The situation is opposite for Central Asia.展开更多
A novel Ga N-based vertical heterostructure field effect transistor（HFET） with nonuniform doping superjunctions（non-SJ HFET） is proposed and studied by Silvaco-ATLAS,for minimizing the specific on-resistance（RonA...A novel Ga N-based vertical heterostructure field effect transistor（HFET） with nonuniform doping superjunctions（non-SJ HFET） is proposed and studied by Silvaco-ATLAS,for minimizing the specific on-resistance（RonA） at no expense of breakdown voltage（BV）.The feature of non-SJ HFET lies in the nonuniform doping concentration from top to bottom in the n-and p-pillars,which is different from that of the conventional Ga N-based vertical HFET with uniform doping superjunctions（un-SJ HFET）.A physically intrinsic mechanism for the nonuniform doping superjunction（non-SJ） to further reduce RonA at no expense of BV is investigated and revealed in detail.The design,related to the structure parameters of non-SJ,is optimized to minimize the RonA on the basis of the same BV as that of un-SJ HFET.Optimized simulation results show that the reduction in RonA depends on the doping concentrations and thickness values of the light and heavy doping parts in non-SJ.The maximum reduction of more than 51% in RonA could be achieved with a BV of 1890 V.These results could demonstrate the superiority of non-SJ HFET in minimizing RonA and provide a useful reference for further developing the Ga N-based vertical HFETs.展开更多
Pairwise thermal entanglement in a three-qubit Heisenberg XX model is investigated when a nonuniform mag- netic field and the Dzyaloshinski-Moriya interaction are included. We find that the nonuniform magnetic field a...Pairwise thermal entanglement in a three-qubit Heisenberg XX model is investigated when a nonuniform mag- netic field and the Dzyaloshinski-Moriya interaction are included. We find that the nonuniform magnetic field and Dzyaloshinski-Moriya interaction are the more efficient control parameters for the increase of entanglement and critical temperature. For both the nearest neighbour sites and the next nearest neighbour sites, the magnetic field can induce entanglement to a certain extent and the Dzyaloshinski-Moriya interaction can enhance the entanglement to a stable value. The steady value of the nearest neighbour site entanglement C12 is larger than the next nearest neighbour site entanglement C13. An interesting phenomenon is that the entanglement curve of C12 appears a peak value when the Dzyaloshinski-Moriya interaction is considered in a nonuniform magnetic field.展开更多
Knowledge of the equilibrium bed-concentration is vital to mathematic a l modeling of the river-bed deformation associated with suspended load but prev i ous investigations only dealt with the reference concentration ...Knowledge of the equilibrium bed-concentration is vital to mathematic a l modeling of the river-bed deformation associated with suspended load but prev i ous investigations only dealt with the reference concentration of uniform sedime nt because of difficulties in observation of the bed-concentration. This work i s a first attempt to develop a theoretical formula for the equilibrium bed-conce n tration of any fraction of nonuniform sediment defined at the bed-surface. The f ormula is based on a stochastic-mechanistic model for the exchange of nonunifor m sediment near the bed, and described as a function of incipient motion probabil ity, non-ceasing probability, pick-up probability, and the ratio of the averag e single-step continuous motion time to static time. Comparison of bed-concentra ti on calculated from the proposed formula with the measured data showed satisfacto ry agreement, indicating the present formula can be used for solving the differe ntial equation governing the motion of suspended load.展开更多
In this study, the consensus problem for a class of second-order multi-agent systems with nonuniform time delays is investigated. A linear consensus protocol is used to make all agents reach consensus and move with a ...In this study, the consensus problem for a class of second-order multi-agent systems with nonuniform time delays is investigated. A linear consensus protocol is used to make all agents reach consensus and move with a constant velocity. By a frequency-domain analysis, a simplified sufficient condition is given to guarantee the consensus stability of the dynamic system. Finally, the effectiveness of the obtained theoretical results is illustrated through numerical simulations.展开更多
In a large-scale wireless sensor network(WSN),densely distributed sensor nodes process a large amount of data.The aggregation of data in a network can consume a great amount of energy.To balance and reduce the energy ...In a large-scale wireless sensor network(WSN),densely distributed sensor nodes process a large amount of data.The aggregation of data in a network can consume a great amount of energy.To balance and reduce the energy consumption of nodes in a WSN and extend the network life,this paper proposes a nonuniform clustering routing algorithm based on the improved K-means algorithm.The algorithm uses a clustering method to form and optimize clusters,and it selects appropriate cluster heads to balance network energy consumption and extend the life cycle of the WSN.To ensure that the cluster head(CH)selection in the network is fair and that the location of the selected CH is not concentrated within a certain range,we chose the appropriate CH competition radius.Simulation results show that,compared with LEACH,LEACH-C,and the DEEC clustering algorithm,this algorithm can effectively balance the energy consumption of the CH and extend the network life.展开更多
After cooling in the hot rolling process,the metallographic structure of microalloyed dual-phase steel is nonuniform along the rolling direction,while the thickness fluctuation of microalloyed dual-phase steel with a ...After cooling in the hot rolling process,the metallographic structure of microalloyed dual-phase steel is nonuniform along the rolling direction,while the thickness fluctuation of microalloyed dual-phase steel with a nonuniform metallographic structure will occur during cold rolling.The mechanism of nonuniform phase transformation of microalloyed dual-phase steels was studied during the cooling process after hot rolling,and the nonuniform phase transformation of microalloyed dual-phase steel was regulated during the cooling process after hot rolling through process optimization.First,the empirical equation of phase transformation temperature was measured by a dilatometer considering thermal expansion.Then,the phase field and temperature field of laminar cooling process were calculated to provide initial boundary conditions for the finite element model.After that,the coupling finite element model of the temperature phase transformation of the strip steel in coiling transportation process was established.The simulation results show that the different thermal contact conditions of the microalloyed dual-phase steel during coil transportation lead to uneven cooling of the coil,which leads to nonuniform transformation of the coil along the rolling direction.In addition,by prolonging the time interval from coiling to unloading,the phenomenon of nonuniform phase transformation of microalloyed dual-phase steel can be effectively controlled.The simulation results are applied to industrial production.The application results show that prolonging the time interval from coiling to unloading can effectively improve the nonuniform phase transformation of microalloyed dual-phase steel in the cooling process after hot rolling.展开更多
The nonuniform distribution of interference spectrum in wavenumber k-space is a key issue to limit the imaging quality of Fourier-domain optical coherence tomography(FD-OCT).At present,the reconstruction quality at di...The nonuniform distribution of interference spectrum in wavenumber k-space is a key issue to limit the imaging quality of Fourier-domain optical coherence tomography(FD-OCT).At present,the reconstruction quality at different depths among a variety of processing methods in k-space is still uncertain.Using simulated and experimental interference spectra at different depths,the effects of common six processing methods including uniform resampling(linear interpolation(LI),cubic spline interpolation(CSI),time-domain interpolation(TDI),and K-B window convolution)and nonuniform sampling direct-reconstruction(Lomb periodogram(LP)and nonuniform discrete Fourier transform(NDFT))on the reconstruction quality of FD-OCT were quantitatively analyzed and compared in this work.The results obtained by using simulated and experimental data were coincident.From the experimental results,the averaged peak intensity,axial resolution,and signal-to-noise ratio(SNR)of NDFT at depth from 0.5 to 3.0mm were improved by about 1.9 dB,1.4 times,and 11.8 dB,respectively,compared to the averaged indices of all the uniform resampling methods at all depths.Similarly,the improvements of the above three indices of LP were 2.0 dB,1.4 times,and 11.7 dB,respectively.The analysis method and the results obtained in this work are helpful to select an appropriate processing method in k-space,so as to improve the imaging quality of FD-OCT.展开更多
Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution.This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution,to...Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution.This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution,to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious nonuniformity.Relations are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier transform.With simulated optical measurement using H2O feature at 7185.6 cm-1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model,this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2×10^(-3).This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz,and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler velocimetry.This proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations,which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.展开更多
Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonun...Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design.展开更多
The periodic nonuniform folded waveguides are special structures, the physical dimension of which is between the periodic folded waveguide and the tapering period folded waveguide. Therefore, the synchronization betwe...The periodic nonuniform folded waveguides are special structures, the physical dimension of which is between the periodic folded waveguide and the tapering period folded waveguide. Therefore, the synchronization between the microwave and the electron beam can be maintained in the whole interaction process and the periods are not tapered. In comparison with the tapering period folded waveguide, the theoretical analysis and the technological requirements for this structure are more convenient. In order to study this structure, the space harmonics are analysed, the conditions to make the rn-th space harmonic synchronizing with the electron beam in the whole interaction process are present, and the dispersion curve and the coupling impedance curve are obtained by the simulation software HFSS.展开更多
Numerical solver using a uniform grid is popular due to its simplicity and low computational cost, but would be unfeasible in the presence of tiny structures in large-scale media. It is necessary to use a nonuniform g...Numerical solver using a uniform grid is popular due to its simplicity and low computational cost, but would be unfeasible in the presence of tiny structures in large-scale media. It is necessary to use a nonuniform grid, where upsampling the wavefield from the coarse grid to the fine grid is essential for reducing artifacts. In this paper, we suggest a local refinement scheme using the Fourier interpolation, which is superior to traditional interpolation methods since it is theoretically exact if the input wavefield is band limited.Traditional interpolation methods would fail at high upsampling ratios(say 50); in contrast, our scheme still works well in the same situations, and the upsampling ratio can be any positive integer. A high upsampling ratio allows us to greatly reduce the computational burden and memory demand in the presence of tiny structures and large-scale models, especially for 3D cases.展开更多
In this article, we study reconstruction of nonuniform attenuated SPECT data and present analytic reconstruction formulae which are similar to Novikov＇s inversion formula. Furthermore, we extend Natterer＇s results.
We prove that, for non-uniformly hyperbolic diffeomorphisms in the sense of Young, the local central limit theorem holds, and the speed in the central limit theorem is O（1/√n）.
A hybrid algorithm is presented for nonuniform lossy multiconductor transmission lines (MTL) connected by arbitrary linear load networks. The networks are characterized by a state-variable equation which allows a gene...A hybrid algorithm is presented for nonuniform lossy multiconductor transmission lines (MTL) connected by arbitrary linear load networks. The networks are characterized by a state-variable equation which allows a general characterization of dynamic elements in the cascade networks. The method is achieved by the finite difference-time domain (FDTD) algorithm for the MTL, and the skin effect is taken into account, the more accurate method is used to compute the skin effect. And this method is combined with the computation of the nonuniform transmission lines. Finally, several numerical examples are given, these results indicate that: the current of the lossy MTL is smaller than the lossless of the MTL; and when the load networks contain the dynamic element, the transition time of the current is longer than the MTL connected by resistance only.展开更多
In this paper,a sparse nonuniform rectangular array based on spatially spread electromagnetic vector sensor(SNRASSEMVS)is introduced,and a method for estimating 2D-direction of arrival(DOA)and polarization is devised....In this paper,a sparse nonuniform rectangular array based on spatially spread electromagnetic vector sensor(SNRASSEMVS)is introduced,and a method for estimating 2D-direction of arrival(DOA)and polarization is devised.Firstly,according to the special structure of the sparse nonuniform rectangular array(SNRA),a set of accurate but ambiguous direction-cosine estimates can be obtained.Then the steering vector of spatially spread electromagnetic vector sensor(SSEMVS)can be extracted from the array manifold to obtain the coarse but unambiguous direction-cosine estimates.Finally,the disambiguation approach can be used to get the final accurate estimates of 2DDOA and polarization.Compared with some existing methods,the SNRA configuration extends the spatial aperture and refines the parameters estimation accuracy without adding any redundant antennas,as well as reduces the mutual coupling effect.Moreover,the proposed algorithm resolves multiple sources without the priori knowledge of signal information,suffers no ambiguity in the estimation of the Poynting vector,and pairs the x-axis direction cosine with the y-axis direction cosine automatically.Simulation results are given to verify the effectiveness and superiority of the proposed algorithm.展开更多
The thermal entanglement of a three-qubit Heisenberg chain under a nonuniform magnetic field is studied. It is very interesting to note that the next nearest neighbor entanglement （NNNE） could be larger than the nea...The thermal entanglement of a three-qubit Heisenberg chain under a nonuniform magnetic field is studied. It is very interesting to note that the next nearest neighbor entanglement （NNNE） could be larger than the nearest neighbor entanglement （NNE）. We analyze the ground state entanglement, and give the conditions that NNNE is larger than NNE near zero temperature. Our results also show that the nonuniform field could induce the entanglement and improve the threshold temperature at certain parameter region.展开更多
基金support from a Grant-in-Aid for Scientific Research(KAKENHI B),Japan(Project/Area code:23H01505)the Institute for Sustainable Future Society,Waseda Research Institute for Science and Engineering,Research Initiatives in Japansupport from the Chinese Scholar Council for PhD scholarships(Grant No.202206220061)was acknowledged。
文摘This paper presents a method for obtaining the displacement of sand particles in a sand–bentonite mixture(SBM)when saturated with water,based on particle tracking velocimetry(PTV).The raw photographs were first converted into binary images.The sand particles were then detected,and the displacement of the sand particles was obtained by comparing their positions in adjacent images.The swelling strain induced by saturation was also obtained using the proposed PTV method.This method was validated by comparing the result with those obtained using a displacement transducer.Subsequently,a comparative analysis of sand particle displacements was conducted for specimens with varying bentonite content(BC),initial thickness,and water infiltration directions.The experimental results obtained were as follows:(1)For specimens with different BCs,local swelling displacement of sand particles at the top part of the specimen increased with higher BCs;(2)For specimens with various heights(hsp),larger local swelling displacement was generated at lower hsp at the initial state;(3)Local swelling characteristics differed in different water infiltration directions.Top-side infiltration showed a significant downward movement of particles during the first several hours of swelling.An estimation method for the dry density distribution of the specimen was proposed based on PTV data and then verified by slicing dry density and water content measurement results.
基金Supported by the China Postdoctoral Science Foundation Funded Project (No. 20080440386)
文摘In this paper, a process modeling and related optimizing control for nonuniformly sampled （NUS） systems are addressed. By using a proposed nonuniform integration filter and subspace method estimation, an identification method of NUS systems is developed, based on which either an output soft sensor or a hidden state estimator is developed. The optimizing control is implemented by replacing the sparsely-mea- sured/immeasurable variable with the estimated one. Examples of optimizing control problem are given. The proposed optimizing control strategy in the simulation examples is verified to be very effeetive.
基金financially supported by the National Natural Science Foundation of China (Nos. 51105068 and 51475086)the Fundamental Research Funds for the Central Universities (Nos. N130323003 and XNB201413)the Science and Technology Research Project for Higher School of Hebei Province (No. Z2013068)
文摘The deformation characteristics of tailor rolled blank （TRB） in the course of uniaxial tension were studied by means of analysis, test and simulation. The mechanical analytical model of TRB during uniaxial tension was set up, and the deformation formulae for the thinner side and for the thicker side were derived to quantify the deformation of TRB. On this basis, uniaxial tension tests on TRB and ordinary blanks （the thinner side and the thicker side of TRB） were conducted. Lagrange polynomial interpolation method was adopted to construct the stress-strain fields of unannealed and annealed TRBs for solving TRB material parameters, and then, uniaxial tension simulation on TRB was completed. Deformations and properties of unannealed TRB were compared with those of annealed TRB, and the thinner side and the thicker side were also compared. Finally, the research results were explained by metallurgical structure. The results show that nonuniform deformation happens in TRB during uniaxial tension, and the necking occurs on the thinner side. The agreement of analysis, test and simulation confirms the correctness of the analytical model and the deformation formulae. The findings of this paper can lay the foundation for the future study on TRB stamping formability and provide a way for TRB modeling.
基金supported by the National Key Research and Development Program of Ministry of Science and Technology of China (Grant 2018YFA0606403 and 2015CB453202)
文摘Based on ensemble experiments with three atmospheric general circulation models(AGCMs), this study investigates the role of the Atlantic Multidecadal Oscillation(AMO) in shaping the summer nonuniform warming over the Eurasian continent since the mid-1990 s. The results validate that the positive-phase AMO can indeed cause nonuniform warming,with predominant amplified warming over Europe–West Asia and Northeast Asia, but with much weaker warming over Central Asia. The underlying mechanism is then diagnosed from the perspective that the boundary forcing modulates the intrinsic atmospheric variability. The results highlight the role of the Silk Road Pattern(SRP), an intrinsic teleconnection pattern across the subtropical Eurasian continent propagating along the Asian jet. The SRP can not only be identified from the AGCM control experiments with the climatological sea surface temperature(SST), but can also be simulated by the AMO-related SST anomaly(SSTA) forcing. Furthermore, diagnostic linear baroclinic model experiments are conducted, and the results suggest that the SRP can be triggered by the AMO-related tropical diabatic heating. The AMO-triggered SRP-like responses feature anticyclonic circulations over Europe–West Asia and Northeast Asia, but cyclonic circulation over Central Asia. These responses cause increased warm advection towards Europe–West Asia and Northeast Asia, reduced precipitation and cloud cover, and then increased downward shortwave radiation. This increased warm advection and increased downward shortwave radiation together cause amplified warming in Europe–West Asia and Northeast Asia. The situation is opposite for Central Asia.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574112,61334002,61474091,and 61574110)the Natural Science Basic Research Plan in Shaanxi Province,China(Grant No.605119425012)
文摘A novel Ga N-based vertical heterostructure field effect transistor（HFET） with nonuniform doping superjunctions（non-SJ HFET） is proposed and studied by Silvaco-ATLAS,for minimizing the specific on-resistance（RonA） at no expense of breakdown voltage（BV）.The feature of non-SJ HFET lies in the nonuniform doping concentration from top to bottom in the n-and p-pillars,which is different from that of the conventional Ga N-based vertical HFET with uniform doping superjunctions（un-SJ HFET）.A physically intrinsic mechanism for the nonuniform doping superjunction（non-SJ） to further reduce RonA at no expense of BV is investigated and revealed in detail.The design,related to the structure parameters of non-SJ,is optimized to minimize the RonA on the basis of the same BV as that of un-SJ HFET.Optimized simulation results show that the reduction in RonA depends on the doping concentrations and thickness values of the light and heavy doping parts in non-SJ.The maximum reduction of more than 51% in RonA could be achieved with a BV of 1890 V.These results could demonstrate the superiority of non-SJ HFET in minimizing RonA and provide a useful reference for further developing the Ga N-based vertical HFETs.
文摘Pairwise thermal entanglement in a three-qubit Heisenberg XX model is investigated when a nonuniform mag- netic field and the Dzyaloshinski-Moriya interaction are included. We find that the nonuniform magnetic field and Dzyaloshinski-Moriya interaction are the more efficient control parameters for the increase of entanglement and critical temperature. For both the nearest neighbour sites and the next nearest neighbour sites, the magnetic field can induce entanglement to a certain extent and the Dzyaloshinski-Moriya interaction can enhance the entanglement to a stable value. The steady value of the nearest neighbour site entanglement C12 is larger than the next nearest neighbour site entanglement C13. An interesting phenomenon is that the entanglement curve of C12 appears a peak value when the Dzyaloshinski-Moriya interaction is considered in a nonuniform magnetic field.
文摘Knowledge of the equilibrium bed-concentration is vital to mathematic a l modeling of the river-bed deformation associated with suspended load but prev i ous investigations only dealt with the reference concentration of uniform sedime nt because of difficulties in observation of the bed-concentration. This work i s a first attempt to develop a theoretical formula for the equilibrium bed-conce n tration of any fraction of nonuniform sediment defined at the bed-surface. The f ormula is based on a stochastic-mechanistic model for the exchange of nonunifor m sediment near the bed, and described as a function of incipient motion probabil ity, non-ceasing probability, pick-up probability, and the ratio of the averag e single-step continuous motion time to static time. Comparison of bed-concentra ti on calculated from the proposed formula with the measured data showed satisfacto ry agreement, indicating the present formula can be used for solving the differe ntial equation governing the motion of suspended load.
基金Project supported by the National Basic Research Program of China (Grant No. 2012CB215203)the Key Program of the National Natural Science Foundation of China (Grant No. 51036002)the Fundamental Research Funds for the Central Universities of China (Grant No. JB2012008)
文摘In this study, the consensus problem for a class of second-order multi-agent systems with nonuniform time delays is investigated. A linear consensus protocol is used to make all agents reach consensus and move with a constant velocity. By a frequency-domain analysis, a simplified sufficient condition is given to guarantee the consensus stability of the dynamic system. Finally, the effectiveness of the obtained theoretical results is illustrated through numerical simulations.
基金This research was funded by the Science and Technology Support Plan Project of Hebei Province(grant numbers 17210803D and 19273703D)the Science and Technology Spark Project of the Hebei Seismological Bureau(grant number DZ20180402056)+1 种基金the Education Department of Hebei Province(grant number QN2018095)the Polytechnic College of Hebei University of Science and Technology.
文摘In a large-scale wireless sensor network(WSN),densely distributed sensor nodes process a large amount of data.The aggregation of data in a network can consume a great amount of energy.To balance and reduce the energy consumption of nodes in a WSN and extend the network life,this paper proposes a nonuniform clustering routing algorithm based on the improved K-means algorithm.The algorithm uses a clustering method to form and optimize clusters,and it selects appropriate cluster heads to balance network energy consumption and extend the life cycle of the WSN.To ensure that the cluster head(CH)selection in the network is fair and that the location of the selected CH is not concentrated within a certain range,we chose the appropriate CH competition radius.Simulation results show that,compared with LEACH,LEACH-C,and the DEEC clustering algorithm,this algorithm can effectively balance the energy consumption of the CH and extend the network life.
基金financially supported by the National Natural Science Foundation of China(Grant No.52004029).
文摘After cooling in the hot rolling process,the metallographic structure of microalloyed dual-phase steel is nonuniform along the rolling direction,while the thickness fluctuation of microalloyed dual-phase steel with a nonuniform metallographic structure will occur during cold rolling.The mechanism of nonuniform phase transformation of microalloyed dual-phase steels was studied during the cooling process after hot rolling,and the nonuniform phase transformation of microalloyed dual-phase steel was regulated during the cooling process after hot rolling through process optimization.First,the empirical equation of phase transformation temperature was measured by a dilatometer considering thermal expansion.Then,the phase field and temperature field of laminar cooling process were calculated to provide initial boundary conditions for the finite element model.After that,the coupling finite element model of the temperature phase transformation of the strip steel in coiling transportation process was established.The simulation results show that the different thermal contact conditions of the microalloyed dual-phase steel during coil transportation lead to uneven cooling of the coil,which leads to nonuniform transformation of the coil along the rolling direction.In addition,by prolonging the time interval from coiling to unloading,the phenomenon of nonuniform phase transformation of microalloyed dual-phase steel can be effectively controlled.The simulation results are applied to industrial production.The application results show that prolonging the time interval from coiling to unloading can effectively improve the nonuniform phase transformation of microalloyed dual-phase steel in the cooling process after hot rolling.
基金supported by the National Natural Science Foundation of China(Grant Nos.61575205 and 62175022)Sichuan Natural Science Foundation(2022NSFSC0803)Sichuan Science and Technology Program(2021JDRC0035).
文摘The nonuniform distribution of interference spectrum in wavenumber k-space is a key issue to limit the imaging quality of Fourier-domain optical coherence tomography(FD-OCT).At present,the reconstruction quality at different depths among a variety of processing methods in k-space is still uncertain.Using simulated and experimental interference spectra at different depths,the effects of common six processing methods including uniform resampling(linear interpolation(LI),cubic spline interpolation(CSI),time-domain interpolation(TDI),and K-B window convolution)and nonuniform sampling direct-reconstruction(Lomb periodogram(LP)and nonuniform discrete Fourier transform(NDFT))on the reconstruction quality of FD-OCT were quantitatively analyzed and compared in this work.The results obtained by using simulated and experimental data were coincident.From the experimental results,the averaged peak intensity,axial resolution,and signal-to-noise ratio(SNR)of NDFT at depth from 0.5 to 3.0mm were improved by about 1.9 dB,1.4 times,and 11.8 dB,respectively,compared to the averaged indices of all the uniform resampling methods at all depths.Similarly,the improvements of the above three indices of LP were 2.0 dB,1.4 times,and 11.7 dB,respectively.The analysis method and the results obtained in this work are helpful to select an appropriate processing method in k-space,so as to improve the imaging quality of FD-OCT.
基金the China Scholarship Council(Grant No.201906845059)the Young Scientists Found of the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20190439)the Fundamental Research Funds of National Key Laboratory of Transient Physics(Grant No.6142604200202)。
文摘Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution.This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution,to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious nonuniformity.Relations are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier transform.With simulated optical measurement using H2O feature at 7185.6 cm-1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model,this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2×10^(-3).This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz,and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler velocimetry.This proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations,which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.
基金National Natural Science Foundation of China under Grant Nos.51921006 and 51725801Fundamental Research Funds for the Central Universities under Grant No.FRFCU5710093320Heilongjiang Touyan Innovation Team Program。
文摘Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design.
基金supported by the National Natural Science Foundation of China (Grant Nos 60532010 and 60401005)
文摘The periodic nonuniform folded waveguides are special structures, the physical dimension of which is between the periodic folded waveguide and the tapering period folded waveguide. Therefore, the synchronization between the microwave and the electron beam can be maintained in the whole interaction process and the periods are not tapered. In comparison with the tapering period folded waveguide, the theoretical analysis and the technological requirements for this structure are more convenient. In order to study this structure, the space harmonics are analysed, the conditions to make the rn-th space harmonic synchronizing with the electron beam in the whole interaction process are present, and the dispersion curve and the coupling impedance curve are obtained by the simulation software HFSS.
基金supported by the National Natural Science Foundation of China (Grant No.41130418)the National Major Project of China (under grant 2017ZX05008-007)+1 种基金supports from the Youth Innovation Promotion Association CAS (2012054)Foundation for Excellent Member of the Youth Innovation Promotion Association (2016)
文摘Numerical solver using a uniform grid is popular due to its simplicity and low computational cost, but would be unfeasible in the presence of tiny structures in large-scale media. It is necessary to use a nonuniform grid, where upsampling the wavefield from the coarse grid to the fine grid is essential for reducing artifacts. In this paper, we suggest a local refinement scheme using the Fourier interpolation, which is superior to traditional interpolation methods since it is theoretically exact if the input wavefield is band limited.Traditional interpolation methods would fail at high upsampling ratios(say 50); in contrast, our scheme still works well in the same situations, and the upsampling ratio can be any positive integer. A high upsampling ratio allows us to greatly reduce the computational burden and memory demand in the presence of tiny structures and large-scale models, especially for 3D cases.
基金supported by the National Natural Science Foundation of China(61271398)Natural Science Foundation of Zhejiang Province(LY14A010004)K.C.Wong Magna Fund in Ningbo University
文摘In this article, we study reconstruction of nonuniform attenuated SPECT data and present analytic reconstruction formulae which are similar to Novikov＇s inversion formula. Furthermore, we extend Natterer＇s results.
基金Supported by NSF of China (10571174)the Scientific Research Foundation of Ministry of Education for Returned Overseas Chinese Scholarsthe Scientific Research Foundation of Ministry of Human and Resources and Social Security of China for Returned Overseas Scholars
文摘We prove that, for non-uniformly hyperbolic diffeomorphisms in the sense of Young, the local central limit theorem holds, and the speed in the central limit theorem is O（1/√n）.
文摘A hybrid algorithm is presented for nonuniform lossy multiconductor transmission lines (MTL) connected by arbitrary linear load networks. The networks are characterized by a state-variable equation which allows a general characterization of dynamic elements in the cascade networks. The method is achieved by the finite difference-time domain (FDTD) algorithm for the MTL, and the skin effect is taken into account, the more accurate method is used to compute the skin effect. And this method is combined with the computation of the nonuniform transmission lines. Finally, several numerical examples are given, these results indicate that: the current of the lossy MTL is smaller than the lossless of the MTL; and when the load networks contain the dynamic element, the transition time of the current is longer than the MTL connected by resistance only.
基金This work was supported by the innovation project of Science and Technology Commission of the Central Military Commission。
文摘In this paper,a sparse nonuniform rectangular array based on spatially spread electromagnetic vector sensor(SNRASSEMVS)is introduced,and a method for estimating 2D-direction of arrival(DOA)and polarization is devised.Firstly,according to the special structure of the sparse nonuniform rectangular array(SNRA),a set of accurate but ambiguous direction-cosine estimates can be obtained.Then the steering vector of spatially spread electromagnetic vector sensor(SSEMVS)can be extracted from the array manifold to obtain the coarse but unambiguous direction-cosine estimates.Finally,the disambiguation approach can be used to get the final accurate estimates of 2DDOA and polarization.Compared with some existing methods,the SNRA configuration extends the spatial aperture and refines the parameters estimation accuracy without adding any redundant antennas,as well as reduces the mutual coupling effect.Moreover,the proposed algorithm resolves multiple sources without the priori knowledge of signal information,suffers no ambiguity in the estimation of the Poynting vector,and pairs the x-axis direction cosine with the y-axis direction cosine automatically.Simulation results are given to verify the effectiveness and superiority of the proposed algorithm.
基金the Natural Science Foundation of Liaoning Province under Grant No.20031073
文摘The thermal entanglement of a three-qubit Heisenberg chain under a nonuniform magnetic field is studied. It is very interesting to note that the next nearest neighbor entanglement （NNNE） could be larger than the nearest neighbor entanglement （NNE）. We analyze the ground state entanglement, and give the conditions that NNNE is larger than NNE near zero temperature. Our results also show that the nonuniform field could induce the entanglement and improve the threshold temperature at certain parameter region.
