Let R be a ring with involution. It is well-known that an EP element in R is a core invertible element, but the question when a core invertible element is an EP element,the authors answer in this paper. Several new ch...Let R be a ring with involution. It is well-known that an EP element in R is a core invertible element, but the question when a core invertible element is an EP element,the authors answer in this paper. Several new characterizations of star-core, normal and Hermitian elements in R are also presented.展开更多
In this paper,we consider the scattering problem of time-harmonic electromagnetic waves from an infinite cylinder having an open arc Γ and a bounded domain D in R^2 as cross section.We focus on the inverse scattering...In this paper,we consider the scattering problem of time-harmonic electromagnetic waves from an infinite cylinder having an open arc Γ and a bounded domain D in R^2 as cross section.We focus on the inverse scattering problem,that is,to reconstruct the shape of Γ and D from the far-field pattern by using the factorization method.Through establishing a mixed reciprocity relation,we prove that the scatters Γ and D can be uniquely determined by the far-field pattern.Furthermore,the mathematical basis is given to explain that the factorization method is feasible to our problem.At the end of this paper,we give some numerical examples to show the efficaciousness of the algorithms.展开更多
Quantitative paleoclimatic reconstruction is crucial for understanding the operation and evolution of the global climate system.For example,a quantitative paleoclimatic reconstruction for the Last Glacial Maximum(18&#...Quantitative paleoclimatic reconstruction is crucial for understanding the operation and evolution of the global climate system.For example,a quantitative paleoclimatic reconstruction for the Last Glacial Maximum(18±2 ka14C,LGM)is fundamental to understanding the evolution of Earth’s climate during the last glacial-interglacial cycle.Previous quantitative palaeoclimate reconstructions in China are generally based on statistical comparison of modern pollen assemblages and modern climate data.These methods are based on the premise that vegetation-climate interactions remain the same through time,and implicitly assume that the interactions are independent of changes in seasonality and atmospheric CO2concentration.However,these assumptions may not always be valid,which may affect the reconstructions.Here,we present the results of a quantitative study of the LGM climate of China based on an improved inverse vegetation model which incorporates physiological processes combined with a new China Quaternary Pollen Database.The results indicate that during the LGM,mean annual temperature(ANNT),mean temperature of the coldest month(MTCO)and mean temperature of the warmest month in China were lower by~5.6±0.8,~11.0±1.6 and~2.6±0.9°C,respectively,compared to today,and that the changes in ANNT were mainly due to the decrease of MTCO.The ANNT decrease in southern China was~5.5±0.5°C.Mean annual precipitation was lower by~46.3±17.8 mm compared to today and was especially low in northern China(~51.2±21.4 mm)due to the decrease in summer rainfall.Comparison of our results with recent outputs from paleoclimatic modelling reveals that while the latter are broadly consistent with our estimated changes in mean annual climatic parameters,there are substantial differences in the seasonal climatic parameters.Our results highlight the crucial importance of developing seasonal simulation on paleoclimatic models,as well as the need to improve the quality of paleoclimatic reconstructions based on proxy records from geological archi展开更多
In this work,we study boundary value problems for second-order differential equations with singularities of second kind inside an interval.First,we investigate properties of the spectrum,then prove a theorem on comple...In this work,we study boundary value problems for second-order differential equations with singularities of second kind inside an interval.First,we investigate properties of the spectrum,then prove a theorem on completeness of eigenfunctions,and study the inverse problem of reconstructing the differential equation from spectral characteristics.展开更多
Theα5 subunit-containing gamma-amino butyric acid type A receptors(α5 GABAARs)are a distinct subpopulation that are specifically distributed in the mammalian hippocampus and also mediate tonic inhibitory currents in...Theα5 subunit-containing gamma-amino butyric acid type A receptors(α5 GABAARs)are a distinct subpopulation that are specifically distributed in the mammalian hippocampus and also mediate tonic inhibitory currents in hippocampal neurons.These tonic currents can be enhanced by low-dose isoflurane,which is associated with learning and memory impairment.Inverse agonists ofα5 GABAARs,such as L-655,708,are able to reverse the short-term memory deficit caused by low-dose isoflurane in young animals.However,whether these negative allosteric modulators have the same effects on aged rats remains unclear.In the present study,we mainly investigated the effects of L-655,708 on low-dose(1.3%)isoflurane-induced learning and memory impairment in elderly rats.Young(3-month-old)and aged(24-month-old)Wistar rats were randomly assigned to receive L-655,708 0.5 hour before or 23.5 hours after 1.3%isoflurane anesthesia.The Morris Water Maze tests demonstrated that L-655,708 injected before or after anesthesia could reverse the memory deficit in young rats.But in aged rats,application of L-655,708 only before anesthesia showed similar effects.Reverse transcription-polymerase chain reaction showed that low-dose isoflurane decreased the mRNA expression ofα5 GABAARs in aging hippocampal neurons but increased that in young animals.These findings indicate that L-655,708 prevented but could not reverse 1.3%isoflurane-induced spatial learning and memory impairment in aged Wistar rats.All experimental procedures and protocols were approved by the Experimental Animal Ethics Committee of Academy of Military Medical Science of China(approval No.NBCDSER-IACUC-2015128)in December 2015.展开更多
The aim of current work is to improve the existing inverse methodology of void-detection based on a target impedance curve,leading to quick-prediction of the parameters of single circular void.In this work,mode-shape ...The aim of current work is to improve the existing inverse methodology of void-detection based on a target impedance curve,leading to quick-prediction of the parameters of single circular void.In this work,mode-shape dependent shifting phenomenon of peaks of impedance curve with change in void location has been analyzed.A number of initial guesses followed by an iterative optimization algorithm based on univariate method has been used to solve the problem.In each iteration starting from each initial guess,the difference between the computationally obtained impedance curve and the target impedance curve has been reduced.This methodology has been extended to detect single circular metallic inclusion in 2D piezoelectric cantilever beam.A good accuracy level was observed for detection of flaw radius and flaw-location along beam-length,but not the precise location along beam-width.展开更多
As the air combat environment becomes more complicated and changeable, accurate threat assessment of air target has a significant impact on air defense operations. This paper proposes an improved generalized intuition...As the air combat environment becomes more complicated and changeable, accurate threat assessment of air target has a significant impact on air defense operations. This paper proposes an improved generalized intuitionistic fuzzy soft set (GIFSS) method for dynamic assessment of air target threat. Firstly, the threat assessment index is reasonably determined by analyzing the typical characteristics of air targets. Secondly, after the GIFSS at different time is obtained, the index weight is determined by the intuitionistic fuzzy set entropy and the relative entropy theory. Then, the inverse Poisson distribution method is used to determine the weight of time series, and then the time-weighted GIFSS is obtained. Finally, threat assessment of five air targets is carried out by using the improved GIFSS (I-GIFSS) and comparison methods. The validity and superiority of the proposed method are verified by calculation and comparison.展开更多
Environmental load is the primary factor in the design of offshore engineering structures and ocean current is the principal environmental load that causes underwater structural failure.In computational analysis,the c...Environmental load is the primary factor in the design of offshore engineering structures and ocean current is the principal environmental load that causes underwater structural failure.In computational analysis,the calculation of current load is mainly based on the current profile.The current profile model,which is based on a structural failure criterion,is conducive to decreasing the uncertainty of the current load.In this study,we used prototype monitoring data and the empirical orthogonal function(EOF)method to investigate the current profile in the South China Sea and its correlation with the design of underwater structural strength and the dynamic design of fatigue.The underwater structural strength design takes into account the size of the structure and the service water depth.We propose profiles for the overall and local designs using the inverse first-order reliability method(IFORM).We extracted the characteristic profile current(CPC)of the monitored sea area to solve dynamic design problems such as vortex-induced vibration(VIV).We used random sampling to verify the feasibility of using the EOF method to calculate the CPC from the current data and identified the main problems associated with using the CPC,which deserve close attention in VIV design.Our research conclusions provide direct references for determining current load in this sea area.This analysis method can also be used in the analysis of other sea areas or field variables.展开更多
An optimal(practical) stabilization problem is formulated in an inverse approach and solved for nonlinear evolution systems in Hilbert spaces. The optimal control design ensures global well-posedness and global practi...An optimal(practical) stabilization problem is formulated in an inverse approach and solved for nonlinear evolution systems in Hilbert spaces. The optimal control design ensures global well-posedness and global practical K∞-exponential stability of the closed-loop system, minimizes a cost functional,which appropriately penalizes both state and control in the sense that it is positive definite(and radially unbounded) in the state and control, without having to solve a Hamilton-Jacobi-Belman equation(HJBE). The Lyapunov functional used in the control design explicitly solves a family of HJBEs. The results are applied to design inverse optimal boundary stabilization control laws for extensible and shearable slender beams governed by fully nonlinear partial differential equations.展开更多
Structural health monitoring is important to ensuring the health and safety of dams.An inverse analysis method based on a novel hybrid fireworks algorithm (FWA) and the radial basis function (RBF) model is proposed to...Structural health monitoring is important to ensuring the health and safety of dams.An inverse analysis method based on a novel hybrid fireworks algorithm (FWA) and the radial basis function (RBF) model is proposed to diagnose the health condition of concrete dams.The damage of concrete dams is diagnosed by identifying the elastic modulus of materials using the displacement changes at different reservoir water levels.FWA is a global optimization intelligent algorithm.The proposed hybrid algorithm combines the FWA with the pattern search algorithm, which has a high capability for local optimization.Examples of benchmark functions and pseudo-experiment examples of concrete dams illustrate that the hybrid FWA improves the convergence speed and robustness of the original algorithm.To address the time consumption problem, an RBF-based surrogate model was established to replace part of the finite element method in inverse analysis.Numerical examples of concrete dams illustrate that the use of an RBF-based surrogate model significantly reduces the computation time of inverse analysis with little influence on identification accuracy.The presented hybrid FWA combined with the RBF network can quickly and accurately determine the elastic modulus of materials, and then determine the health status of the concrete dam.展开更多
In this paper,design,re-design,and performance of a long-standing very deep excavation,which was originally planned to depth of 38 m,are presented.Over-digging was not planned in the original design,thus the reassessm...In this paper,design,re-design,and performance of a long-standing very deep excavation,which was originally planned to depth of 38 m,are presented.Over-digging was not planned in the original design,thus the reassessment was performed.Two main topics were followed:deepening to increase the maximum depth of an existent excavation from 38 m to 42.5 m,and feasibility for upgrading a predesigned support system from temporary to permanent support system.The geological investigations in the project site illustrated a type of stiff and cemented coarse-grained alluvium.An observational approach with additional geotechnical investigations and in situ tests was applied.Back analyses of stability of an unsupported access ramp,as well as deformation monitoring of walls,were used in order to review geotechnical design parameters that represent the full-scale behavior of the ground.Additional nails and soldier piles together with building mat foundation were implemented as a complementary lateral support in the retaining system.From an engineering point of view,by assuming a corrosion rate of 0.065 mm/a for existent rebars,according to chemical and electrical resistivity tests,the long-term performance of the revised retaining system was verified by static and pseudo-dynamic ultimate limit state analyses.Performance monitoring during the construction shows that the measured deformation is in the lower limit of the prediction.展开更多
We evaluate the topological charge density of SU(3) gauge fields on a lattice by calculating the trace of the overlap Dirac matrix employing the symmetric multi-probing(SMP) method in 3 modes. Since the topological ch...We evaluate the topological charge density of SU(3) gauge fields on a lattice by calculating the trace of the overlap Dirac matrix employing the symmetric multi-probing(SMP) method in 3 modes. Since the topological charge Q for a given lattice configuration must be an integer number, it is easy to estimate the systematic error(the deviation of Q to the nearest integer). The results demonstrate a high efficiency and accuracy in calculating the trace of the inverse of a large sparse matrix with locality by using the SMP sources when compared to using point sources.We also show the correlation between the errors and probing scheme parameter rmin, as well as lattice volume NL and lattice spacing a. It is found that the computational time for calculating the trace by employing the SMP sources is less dependent on NL than by using point sources. Therefore, the SMP method is very suitable for calculations on large lattices.展开更多
The G protein-coupled receptors 3,6,and 12(GPR3,GPR6,and GPR12)comprise a family of closely related orphan receptors with no con firmed en dogenous liga nds.These receptors are con stitutively active and capable of si...The G protein-coupled receptors 3,6,and 12(GPR3,GPR6,and GPR12)comprise a family of closely related orphan receptors with no con firmed en dogenous liga nds.These receptors are con stitutively active and capable of signaling through G protein-mediated and non-G protein-mediated mechanisms.These orphan receptors have previously been reported to play important roles in many normal physiological functions and to be involved in a variety of pathological conditions.Although they are orphans,GPR3,GPR6,and GPR12 are phylogenetically most closely related to the cannabinoid receptors.Using β-arrestin2 recruitment and cAMP accumulati on assays,we recently found that the non psychoactive phytoca nnabinoid cann abidiol(CBD)is an inverse agonist for GPR3,GPR6,and GPR12.This discovery highlights these orphan receptors as potential new molecular targets for CBD,provides novel mechanisms of action,and suggests new therapeutic uses of CBD for illnesses such as Alzheimer's disease,Parkinson's disease,can cer,and infertility.Furthermore,identificati on of CBD as a new in verse agonist for GPR3,GPR6,and GPR12 provides the initial chemical scaffolds upon which potent and efficacious agents acting on these receptors can be developed,with the goal of developing chemical tools for studying these orphan receptors and ultimately new therapeutic agents.展开更多
The magnetic properties of inverse ferrite (Fe^3+)[Fe^3+Co^2+]O4^2-,(Fe^3+)[Fe^3+Cu^2+]O4^2,( Fe^3+)[Fe^3+Fe^2+]O4^2,and (Fe^3+)[Fe^3+Ni^2+]O4^2- spinels have been studied using Monte Carlo simulation.We have also cal...The magnetic properties of inverse ferrite (Fe^3+)[Fe^3+Co^2+]O4^2-,(Fe^3+)[Fe^3+Cu^2+]O4^2,( Fe^3+)[Fe^3+Fe^2+]O4^2,and (Fe^3+)[Fe^3+Ni^2+]O4^2- spinels have been studied using Monte Carlo simulation.We have also calculated the critical and Curie Weiss temperatures from the thermal magnetizations and inverse of magnetic susceptibilities for each system.Magnetic hysteresis cycles have been found for the four systems.Finally,we found the critical exponents associated with magnetization,magnetic susceptibility,and external magnetic field.Our results of critical and Curie Weiss temperatures are similar to those obtained by experiment results.The critical exponents are similar to those of known 3D-Ising model.展开更多
To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic ...To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffiiess and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffiiess and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.展开更多
Considering the high safety,low-cost and high capacity,aqueous zinc ion batteries have been a potential candidate for energy storage ensuring smooth electricity supply.Herein,we have synthesized inverse opal manganese...Considering the high safety,low-cost and high capacity,aqueous zinc ion batteries have been a potential candidate for energy storage ensuring smooth electricity supply.Herein,we have synthesized inverse opal manganese dioxide constructed by few-layered ultrathin nanosheets by a solution template method at mild temperature.The ultrathin nanosheets with the thickness as small as 1 nm are well separated without obvious aggregation.Used as cathode material for aqueous zinc ion batteries,the few-layered ultrathin nanosheets combined with the inverse opal structure guarantee excellent performance.A high specific discharge capacity of 262.9 mAh·g^-1 is retained for the 100th cycle at a current density of 300 mA·g^-1 with a high capacity retention of 95.6%.A high specific discharge capacity of 121 mAh·g^-1 at a high current density of 2,000 mA·g^-1 is achieved even after 5,000 long-term cycles.The ex-situ X-ray diffraction (XRD) patterns,selected-area electron diffraction (SAED) patterns and high-resolution transmission electron microscopy (HRTEM) results demonstrate that the discharge/charge processes involve the reversible formation of zinc sulfate hydroxide hydrate on the cathode while in-plane crystal structure of the layered bimessite MnO2 could be maintained.This unique structured MnO2 is a promising candidate as cathode material for high capacity,high rate capability and long-term aqueous zinc-ion batteries.展开更多
BACKGROUND As the malignant tumor,pancreatic cancer with a meager 5-years survival rate has been widely concerning.However,the molecular mechanisms that result in malignant transformation of pancreatic cells remain el...BACKGROUND As the malignant tumor,pancreatic cancer with a meager 5-years survival rate has been widely concerning.However,the molecular mechanisms that result in malignant transformation of pancreatic cells remain elusive.AIM To investigate the gene expression profiles in normal or malignant transformed pancreas development.METHODS MaSigPro and ANOVA were performed on two pancreas development datasets downloaded from the Gene Expression Omnibus database.Six pancreatic cancer datasets collected from TCGA database were used to establish differentially expressed genes related to pancreas development and pancreatic cancer.Moreover,gene clusters with highly similar interpretation patterns between pancreas development and pancreatic cancer progression were established by self-organizing map and singular value decomposition.Additionally,the hypergeometric test was performed to compare the corresponding interpretation patterns.Abnormal regions of metabolic pathway were analyzed using the Subpathway-GM method.RESULTS This study established the continuously upregulated and downregulated genes at different stages in pancreas development and progression of pancreatic cancer.Through analysis of the differentially expressed genes,we established the inverse and consistent direction development-cancer pattern associations.Based on the application of the Subpathway-GM analysis,we established 17 significant metabolic sub-pathways that were closely associated with pancreatic cancer.Of note,the most significant metabolites sub-pathway was related to glycerophospholipid metabolism.CONCLUSION The inverse and consistent direction development-cancer pattern associations were established.There was a significant correlation in the inverse patterns,but not consistent direction patterns.展开更多
Traditional orthogonal frequency division multiplexing(OFDM)transmitter is implemented by exploiting inverse fast Fourier transform(IFFT),up-sampling,and low pass shaping filter(LPSF)modules,which occupy a large numbe...Traditional orthogonal frequency division multiplexing(OFDM)transmitter is implemented by exploiting inverse fast Fourier transform(IFFT),up-sampling,and low pass shaping filter(LPSF)modules,which occupy a large number of hardware resources and severely lower down the operation speed.To address these limitations,we propose a novel OFDM transmitter architecture,by which the aforementioned modules can be discarded and replaced with some simple switches.In the proposed architecture,direct digital synthesis(DDS)method is employed to generate digital sub-carriers and to transform OFDM data from frequency domain to time domain.Through some sophisticated simplifications,the proposed architecture can avoid using multipliers and remarkably save hardware resources.Finally,comparative experiments are carried out on field programmable gate array(FPGA)platform which demonstrates that our DDS-based architecture saves more than half of the hardware resources and doubles the achievable maximum frequency compared with traditional structure.展开更多
基金the National Natural Science Foundation of China (Nos.11201063 11771076)the Ministry of Education and Science,Republic of Serbia (No.174007).
文摘Let R be a ring with involution. It is well-known that an EP element in R is a core invertible element, but the question when a core invertible element is an EP element,the authors answer in this paper. Several new characterizations of star-core, normal and Hermitian elements in R are also presented.
基金the National Naturel Science Foundation(NNSF)of China grant 11601138NNSF of China grant 11571132.
文摘In this paper,we consider the scattering problem of time-harmonic electromagnetic waves from an infinite cylinder having an open arc Γ and a bounded domain D in R^2 as cross section.We focus on the inverse scattering problem,that is,to reconstruct the shape of Γ and D from the far-field pattern by using the factorization method.Through establishing a mixed reciprocity relation,we prove that the scatters Γ and D can be uniquely determined by the far-field pattern.Furthermore,the mathematical basis is given to explain that the factorization method is feasible to our problem.At the end of this paper,we give some numerical examples to show the efficaciousness of the algorithms.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA13010106)the National Key Research and Development Program of China(Grant No.2016YFA0600504)+1 种基金the National Natural Science Foundation of China(Grant Nos.41572165,41430531,41125011&41472319)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05120700).
文摘Quantitative paleoclimatic reconstruction is crucial for understanding the operation and evolution of the global climate system.For example,a quantitative paleoclimatic reconstruction for the Last Glacial Maximum(18±2 ka14C,LGM)is fundamental to understanding the evolution of Earth’s climate during the last glacial-interglacial cycle.Previous quantitative palaeoclimate reconstructions in China are generally based on statistical comparison of modern pollen assemblages and modern climate data.These methods are based on the premise that vegetation-climate interactions remain the same through time,and implicitly assume that the interactions are independent of changes in seasonality and atmospheric CO2concentration.However,these assumptions may not always be valid,which may affect the reconstructions.Here,we present the results of a quantitative study of the LGM climate of China based on an improved inverse vegetation model which incorporates physiological processes combined with a new China Quaternary Pollen Database.The results indicate that during the LGM,mean annual temperature(ANNT),mean temperature of the coldest month(MTCO)and mean temperature of the warmest month in China were lower by~5.6±0.8,~11.0±1.6 and~2.6±0.9°C,respectively,compared to today,and that the changes in ANNT were mainly due to the decrease of MTCO.The ANNT decrease in southern China was~5.5±0.5°C.Mean annual precipitation was lower by~46.3±17.8 mm compared to today and was especially low in northern China(~51.2±21.4 mm)due to the decrease in summer rainfall.Comparison of our results with recent outputs from paleoclimatic modelling reveals that while the latter are broadly consistent with our estimated changes in mean annual climatic parameters,there are substantial differences in the seasonal climatic parameters.Our results highlight the crucial importance of developing seasonal simulation on paleoclimatic models,as well as the need to improve the quality of paleoclimatic reconstructions based on proxy records from geological archi
基金the University of Kashan under grant number 464151/7.
文摘In this work,we study boundary value problems for second-order differential equations with singularities of second kind inside an interval.First,we investigate properties of the spectrum,then prove a theorem on completeness of eigenfunctions,and study the inverse problem of reconstructing the differential equation from spectral characteristics.
文摘Theα5 subunit-containing gamma-amino butyric acid type A receptors(α5 GABAARs)are a distinct subpopulation that are specifically distributed in the mammalian hippocampus and also mediate tonic inhibitory currents in hippocampal neurons.These tonic currents can be enhanced by low-dose isoflurane,which is associated with learning and memory impairment.Inverse agonists ofα5 GABAARs,such as L-655,708,are able to reverse the short-term memory deficit caused by low-dose isoflurane in young animals.However,whether these negative allosteric modulators have the same effects on aged rats remains unclear.In the present study,we mainly investigated the effects of L-655,708 on low-dose(1.3%)isoflurane-induced learning and memory impairment in elderly rats.Young(3-month-old)and aged(24-month-old)Wistar rats were randomly assigned to receive L-655,708 0.5 hour before or 23.5 hours after 1.3%isoflurane anesthesia.The Morris Water Maze tests demonstrated that L-655,708 injected before or after anesthesia could reverse the memory deficit in young rats.But in aged rats,application of L-655,708 only before anesthesia showed similar effects.Reverse transcription-polymerase chain reaction showed that low-dose isoflurane decreased the mRNA expression ofα5 GABAARs in aging hippocampal neurons but increased that in young animals.These findings indicate that L-655,708 prevented but could not reverse 1.3%isoflurane-induced spatial learning and memory impairment in aged Wistar rats.All experimental procedures and protocols were approved by the Experimental Animal Ethics Committee of Academy of Military Medical Science of China(approval No.NBCDSER-IACUC-2015128)in December 2015.
基金the financial support from NSFC(Grant No.11772234)and DAAD(IIT sandwich master program).
文摘The aim of current work is to improve the existing inverse methodology of void-detection based on a target impedance curve,leading to quick-prediction of the parameters of single circular void.In this work,mode-shape dependent shifting phenomenon of peaks of impedance curve with change in void location has been analyzed.A number of initial guesses followed by an iterative optimization algorithm based on univariate method has been used to solve the problem.In each iteration starting from each initial guess,the difference between the computationally obtained impedance curve and the target impedance curve has been reduced.This methodology has been extended to detect single circular metallic inclusion in 2D piezoelectric cantilever beam.A good accuracy level was observed for detection of flaw radius and flaw-location along beam-length,but not the precise location along beam-width.
基金supported by the National Natural Science Foundation of China(51779263).
文摘As the air combat environment becomes more complicated and changeable, accurate threat assessment of air target has a significant impact on air defense operations. This paper proposes an improved generalized intuitionistic fuzzy soft set (GIFSS) method for dynamic assessment of air target threat. Firstly, the threat assessment index is reasonably determined by analyzing the typical characteristics of air targets. Secondly, after the GIFSS at different time is obtained, the index weight is determined by the intuitionistic fuzzy set entropy and the relative entropy theory. Then, the inverse Poisson distribution method is used to determine the weight of time series, and then the time-weighted GIFSS is obtained. Finally, threat assessment of five air targets is carried out by using the improved GIFSS (I-GIFSS) and comparison methods. The validity and superiority of the proposed method are verified by calculation and comparison.
基金the National Natural Science Foundation of China(No.15572072)the National Key Basic Research and Development Program(No.2016ZX05028-002-005).
文摘Environmental load is the primary factor in the design of offshore engineering structures and ocean current is the principal environmental load that causes underwater structural failure.In computational analysis,the calculation of current load is mainly based on the current profile.The current profile model,which is based on a structural failure criterion,is conducive to decreasing the uncertainty of the current load.In this study,we used prototype monitoring data and the empirical orthogonal function(EOF)method to investigate the current profile in the South China Sea and its correlation with the design of underwater structural strength and the dynamic design of fatigue.The underwater structural strength design takes into account the size of the structure and the service water depth.We propose profiles for the overall and local designs using the inverse first-order reliability method(IFORM).We extracted the characteristic profile current(CPC)of the monitored sea area to solve dynamic design problems such as vortex-induced vibration(VIV).We used random sampling to verify the feasibility of using the EOF method to calculate the CPC from the current data and identified the main problems associated with using the CPC,which deserve close attention in VIV design.Our research conclusions provide direct references for determining current load in this sea area.This analysis method can also be used in the analysis of other sea areas or field variables.
文摘An optimal(practical) stabilization problem is formulated in an inverse approach and solved for nonlinear evolution systems in Hilbert spaces. The optimal control design ensures global well-posedness and global practical K∞-exponential stability of the closed-loop system, minimizes a cost functional,which appropriately penalizes both state and control in the sense that it is positive definite(and radially unbounded) in the state and control, without having to solve a Hamilton-Jacobi-Belman equation(HJBE). The Lyapunov functional used in the control design explicitly solves a family of HJBEs. The results are applied to design inverse optimal boundary stabilization control laws for extensible and shearable slender beams governed by fully nonlinear partial differential equations.
基金the National Key Research and Development Program of China (Grants No.2016YFC0401600 and 2017YFC0404906)the National Natural Science Foundation of China (Grants No.51769033 and 51779035)the Fundamental Research Funds for the Central Universities (Grants No.DUT17ZD205 and DUT19LK14).
文摘Structural health monitoring is important to ensuring the health and safety of dams.An inverse analysis method based on a novel hybrid fireworks algorithm (FWA) and the radial basis function (RBF) model is proposed to diagnose the health condition of concrete dams.The damage of concrete dams is diagnosed by identifying the elastic modulus of materials using the displacement changes at different reservoir water levels.FWA is a global optimization intelligent algorithm.The proposed hybrid algorithm combines the FWA with the pattern search algorithm, which has a high capability for local optimization.Examples of benchmark functions and pseudo-experiment examples of concrete dams illustrate that the hybrid FWA improves the convergence speed and robustness of the original algorithm.To address the time consumption problem, an RBF-based surrogate model was established to replace part of the finite element method in inverse analysis.Numerical examples of concrete dams illustrate that the use of an RBF-based surrogate model significantly reduces the computation time of inverse analysis with little influence on identification accuracy.The presented hybrid FWA combined with the RBF network can quickly and accurately determine the elastic modulus of materials, and then determine the health status of the concrete dam.
文摘In this paper,design,re-design,and performance of a long-standing very deep excavation,which was originally planned to depth of 38 m,are presented.Over-digging was not planned in the original design,thus the reassessment was performed.Two main topics were followed:deepening to increase the maximum depth of an existent excavation from 38 m to 42.5 m,and feasibility for upgrading a predesigned support system from temporary to permanent support system.The geological investigations in the project site illustrated a type of stiff and cemented coarse-grained alluvium.An observational approach with additional geotechnical investigations and in situ tests was applied.Back analyses of stability of an unsupported access ramp,as well as deformation monitoring of walls,were used in order to review geotechnical design parameters that represent the full-scale behavior of the ground.Additional nails and soldier piles together with building mat foundation were implemented as a complementary lateral support in the retaining system.From an engineering point of view,by assuming a corrosion rate of 0.065 mm/a for existent rebars,according to chemical and electrical resistivity tests,the long-term performance of the revised retaining system was verified by static and pseudo-dynamic ultimate limit state analyses.Performance monitoring during the construction shows that the measured deformation is in the lower limit of the prediction.
基金Supported in part by the National Natural Science Foundation of China(NSFC)(11335001,11275169).
文摘We evaluate the topological charge density of SU(3) gauge fields on a lattice by calculating the trace of the overlap Dirac matrix employing the symmetric multi-probing(SMP) method in 3 modes. Since the topological charge Q for a given lattice configuration must be an integer number, it is easy to estimate the systematic error(the deviation of Q to the nearest integer). The results demonstrate a high efficiency and accuracy in calculating the trace of the inverse of a large sparse matrix with locality by using the SMP sources when compared to using point sources.We also show the correlation between the errors and probing scheme parameter rmin, as well as lattice volume NL and lattice spacing a. It is found that the computational time for calculating the trace by employing the SMP sources is less dependent on NL than by using point sources. Therefore, the SMP method is very suitable for calculations on large lattices.
基金National Institutes of Health Grants DA11551 and EY13632(to Z-HS),CA134283(to David W Hein)University of Louisville Research Infrastructure Fund R5385(to Z-HS).
文摘The G protein-coupled receptors 3,6,and 12(GPR3,GPR6,and GPR12)comprise a family of closely related orphan receptors with no con firmed en dogenous liga nds.These receptors are con stitutively active and capable of signaling through G protein-mediated and non-G protein-mediated mechanisms.These orphan receptors have previously been reported to play important roles in many normal physiological functions and to be involved in a variety of pathological conditions.Although they are orphans,GPR3,GPR6,and GPR12 are phylogenetically most closely related to the cannabinoid receptors.Using β-arrestin2 recruitment and cAMP accumulati on assays,we recently found that the non psychoactive phytoca nnabinoid cann abidiol(CBD)is an inverse agonist for GPR3,GPR6,and GPR12.This discovery highlights these orphan receptors as potential new molecular targets for CBD,provides novel mechanisms of action,and suggests new therapeutic uses of CBD for illnesses such as Alzheimer's disease,Parkinson's disease,can cer,and infertility.Furthermore,identificati on of CBD as a new in verse agonist for GPR3,GPR6,and GPR12 provides the initial chemical scaffolds upon which potent and efficacious agents acting on these receptors can be developed,with the goal of developing chemical tools for studying these orphan receptors and ultimately new therapeutic agents.
文摘The magnetic properties of inverse ferrite (Fe^3+)[Fe^3+Co^2+]O4^2-,(Fe^3+)[Fe^3+Cu^2+]O4^2,( Fe^3+)[Fe^3+Fe^2+]O4^2,and (Fe^3+)[Fe^3+Ni^2+]O4^2- spinels have been studied using Monte Carlo simulation.We have also calculated the critical and Curie Weiss temperatures from the thermal magnetizations and inverse of magnetic susceptibilities for each system.Magnetic hysteresis cycles have been found for the four systems.Finally,we found the critical exponents associated with magnetization,magnetic susceptibility,and external magnetic field.Our results of critical and Curie Weiss temperatures are similar to those obtained by experiment results.The critical exponents are similar to those of known 3D-Ising model.
基金Fundamental Research Funds for the Central Universities of China (Grant No. N170308028).
文摘To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffiiess and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffiiess and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.
基金the National Research Foundation of Singapore (NRF) Investigatorship,award Number NRF2016NRF-NRFI001-22.
文摘Considering the high safety,low-cost and high capacity,aqueous zinc ion batteries have been a potential candidate for energy storage ensuring smooth electricity supply.Herein,we have synthesized inverse opal manganese dioxide constructed by few-layered ultrathin nanosheets by a solution template method at mild temperature.The ultrathin nanosheets with the thickness as small as 1 nm are well separated without obvious aggregation.Used as cathode material for aqueous zinc ion batteries,the few-layered ultrathin nanosheets combined with the inverse opal structure guarantee excellent performance.A high specific discharge capacity of 262.9 mAh·g^-1 is retained for the 100th cycle at a current density of 300 mA·g^-1 with a high capacity retention of 95.6%.A high specific discharge capacity of 121 mAh·g^-1 at a high current density of 2,000 mA·g^-1 is achieved even after 5,000 long-term cycles.The ex-situ X-ray diffraction (XRD) patterns,selected-area electron diffraction (SAED) patterns and high-resolution transmission electron microscopy (HRTEM) results demonstrate that the discharge/charge processes involve the reversible formation of zinc sulfate hydroxide hydrate on the cathode while in-plane crystal structure of the layered bimessite MnO2 could be maintained.This unique structured MnO2 is a promising candidate as cathode material for high capacity,high rate capability and long-term aqueous zinc-ion batteries.
文摘BACKGROUND As the malignant tumor,pancreatic cancer with a meager 5-years survival rate has been widely concerning.However,the molecular mechanisms that result in malignant transformation of pancreatic cells remain elusive.AIM To investigate the gene expression profiles in normal or malignant transformed pancreas development.METHODS MaSigPro and ANOVA were performed on two pancreas development datasets downloaded from the Gene Expression Omnibus database.Six pancreatic cancer datasets collected from TCGA database were used to establish differentially expressed genes related to pancreas development and pancreatic cancer.Moreover,gene clusters with highly similar interpretation patterns between pancreas development and pancreatic cancer progression were established by self-organizing map and singular value decomposition.Additionally,the hypergeometric test was performed to compare the corresponding interpretation patterns.Abnormal regions of metabolic pathway were analyzed using the Subpathway-GM method.RESULTS This study established the continuously upregulated and downregulated genes at different stages in pancreas development and progression of pancreatic cancer.Through analysis of the differentially expressed genes,we established the inverse and consistent direction development-cancer pattern associations.Based on the application of the Subpathway-GM analysis,we established 17 significant metabolic sub-pathways that were closely associated with pancreatic cancer.Of note,the most significant metabolites sub-pathway was related to glycerophospholipid metabolism.CONCLUSION The inverse and consistent direction development-cancer pattern associations were established.There was a significant correlation in the inverse patterns,but not consistent direction patterns.
基金Supported by the Educational Science Research Project of Hubei Province(B2014243).
文摘Traditional orthogonal frequency division multiplexing(OFDM)transmitter is implemented by exploiting inverse fast Fourier transform(IFFT),up-sampling,and low pass shaping filter(LPSF)modules,which occupy a large number of hardware resources and severely lower down the operation speed.To address these limitations,we propose a novel OFDM transmitter architecture,by which the aforementioned modules can be discarded and replaced with some simple switches.In the proposed architecture,direct digital synthesis(DDS)method is employed to generate digital sub-carriers and to transform OFDM data from frequency domain to time domain.Through some sophisticated simplifications,the proposed architecture can avoid using multipliers and remarkably save hardware resources.Finally,comparative experiments are carried out on field programmable gate array(FPGA)platform which demonstrates that our DDS-based architecture saves more than half of the hardware resources and doubles the achievable maximum frequency compared with traditional structure.