By studying the light isotopic compositions of carbon,oxygen,and hydrogen,combined with previous research results on the ore-forming source of the deposit,the authors try to uncover its metallogenic origin.The δ^(18)...By studying the light isotopic compositions of carbon,oxygen,and hydrogen,combined with previous research results on the ore-forming source of the deposit,the authors try to uncover its metallogenic origin.The δ^(18)O and δ^(13)C isotope signatures of dolomite samples vary between 10.2 and 13.0‰,and between−7.2 and−5.2‰,respectively,implying that the carbon derives from the upper mantle.δD and δ^(18) O of quartz,biotite,and muscovite from diff erent ore veins of the deposit vary between−82 and−59‰,and between 11.6 and 12.4‰,respectively,implying that the metallogenic solutions are mainly magmatic.According to the relevant research results of many isotope geologists,the fractionation degree of hydrogen isotopes increases as the depth to the Earth’s core increases,and the more diff erentiated the hydrogen isotopes are,the lower their values will be.In other words,mantle-derived solutions can have extremely low hydrogen isotope values.This means that the δD‰ value−134 of the pyrrhotite sample numbered SD-34 in this article may indicate mantle-derived oreforming fl uid of the deposit.The formation of the Dashuigou tellurium deposit occurred between 91.71 and 80.19 Ma.展开更多
In this paper, we consider the relationship between the binding number and the existence of fractional k-factors of graphs. The binding number of G is defined by Woodall as bind(G)=min{ | NG(X) || X |:∅≠X⊆V(G) }. It ...In this paper, we consider the relationship between the binding number and the existence of fractional k-factors of graphs. The binding number of G is defined by Woodall as bind(G)=min{ | NG(X) || X |:∅≠X⊆V(G) }. It is proved that a graph G has a fractional 1-factor if bind(G)≥1and has a fractional k-factor if bind(G)≥k−1k. Furthermore, it is showed that both results are best possible in some sense.展开更多
A hypothetical photon mass m_(γ) can produce a frequency-dependent vacuum dispersion of light, which leads to an additional time delay between photons with different frequencies when they propagate through a fixed di...A hypothetical photon mass m_(γ) can produce a frequency-dependent vacuum dispersion of light, which leads to an additional time delay between photons with different frequencies when they propagate through a fixed distance. The dispersion measure and redshift measurements of fast radio bursts(FRBs) have been widely used to constrain the rest mass of the photon. However, all current studies analyzed the effect of the frequency-dependent dispersion for massive photons in the standard ΛCDM cosmological context. In order to alleviate the circularity problem induced by the presumption of a specific cosmological model based on the fundamental postulate of the masslessness of photons, here we employ a new model-independent smoothing technique, artificial neural network(ANN), to reconstruct the Hubble parameter H(z) function from 34 cosmic-chronometer measurements.By combining observations of 32 well-localized FRBs and the H(z) function reconstructed by ANN, we obtain an upper limit of m_(γ) ≤ 3.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 2.0 × 10^(-15)eV/c^(2)(m_(γ) ≤ 6.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 3.6 × 10^(-15)eV/c_(2)) at the 1σ(2σ) confidence level. This is the first cosmology-independent photon mass limit derived from extragalactic sources.展开更多
Four-wheel independently driven electric vehicles(FWID-EV)endow a flexible and scalable control framework to improve vehicle performance.This paper integrates the torque vectoring and active suspension system(ASS)to e...Four-wheel independently driven electric vehicles(FWID-EV)endow a flexible and scalable control framework to improve vehicle performance.This paper integrates the torque vectoring and active suspension system(ASS)to enhance the vehicle’s longitudinal and vertical motion control performance.While the nonlinear characteristic of the tire model leads to a relatively heavier computational burden.To facilitate the controller design and ease the load,a half-vehicle dynamics system is built and simplified to the linear-time-varying(LTV)model.Then a model predictive controller is developed by formulating the objective function by comprehensively considering the safety,energy-saving and comfort requirements.The in-wheel motor efficiency and the power loss of tire slip are treated as optimization indices in this work to reduce energy consumption.Finally,the effectiveness of the proposed controller is verified through the rapid-control-prototype(RCP)test.The results demonstrate the enhancement of the energy-saving as well as comfort on the basis of vehicle stability.展开更多
The most critical obstacle for four-wheel independently driven electric vehicles(4WID-EVs)is the driving range.Being the actuators of 4WID-EVs,motors account for its major power consumption.In this sense,by properly d...The most critical obstacle for four-wheel independently driven electric vehicles(4WID-EVs)is the driving range.Being the actuators of 4WID-EVs,motors account for its major power consumption.In this sense,by properly distributing torques to minimize the power consumption,the driving range of 4WID-EV can be effectively improved.This paper proposes a model predictive control(MPC)-based torque distribution scheme,which minimizes the power consumption of 4WID-EVs while guaranteeing its tracking performance of planar motions.By incorporating the motor model considering iron losses,the optimal torque distribution can be achieved without an additional torque controller.Also,for this reason,the proposed control scheme is computationally efficient,since the power consumption term to be optimized,which is expressed as the product of the motor voltages and currents,is much simpler than that derived from the efficiency map.With reasonable simplification and linearization,the MPC problem is converted to a quadratic programming problem,which can be solved efficiently.The simulation results in MATLAB and CarSim co-simulation environments demonstrate that the proposed scheme effectively reduces power consumption with guaranteed tracking performance.展开更多
As an effort to understand the effect of diabetes on the increasing rate of COVID-19 infection, we embarked upon a detailed statistical analysis of various datasets that include COVID-19 infection and mortality rate, ...As an effort to understand the effect of diabetes on the increasing rate of COVID-19 infection, we embarked upon a detailed statistical analysis of various datasets that include COVID-19 infection and mortality rate, diabetes and diseases that may contribute to the severity and risk factor of diabetes in individuals and this impact on COVID-19 and the mortality rate. These diseases include respiratory diseases, cardiovascular diseases, and obesity. Equally significant is the statistical analysis on ethnicity, age, and sex on COVID-19 infection as well as mortality rate. Their possible contributions to increasing the severity and risk factor of diabetes as a risk to mortality to individuals who have COVID-19. Objectives: The ultimate objectives of this investigation are as follow: 1) Is there a risk factor of diabetes on COVID-19 infection and increasing mortality rate? 2) To what extent do other disease conditions that include, obesity, heart failure, and respiratory diseases influence the severity and risk factor of diabetes on increasing COVID-19 infection and mortality rate? 3) To what extent does age, race, and gender increase the mortality of COVID-19 and increase the severity and risk factor of diabetes on COVID-19 mortality rate? 4) How and why COVID-19 virus increases the risk of diabetes in children? 5) Diabetes and COVID-19: Who is most at Risk? Lastly, understanding the misconception of COVID-19 and diabetes.展开更多
The Dashuigou tellurium deposit is the world’s only known independent tellurium deposit.By restoring metamorphic rocks’protolith,we seek to understand not only the development and evolution trajectory of the region ...The Dashuigou tellurium deposit is the world’s only known independent tellurium deposit.By restoring metamorphic rocks’protolith,we seek to understand not only the development and evolution trajectory of the region but also the origin of the relevant deposits.While there are many ways to restore metamorphic rocks’protolith,we take the host metamorphic rocks of Dashuigou tellurium deposit and leverage various petrochemical eigenvalues and related diagrams previously proposed to reveal the deposit’s host metamorphic rocks’protolith.The petrochemical eigenvalues include molecular number,Niggli’s value,REE parity ratio,CaO/Al_(2)O_(3)ratio,Fe^(3+) /(Fe^(3+) -+Fe^(2+) )ratio,chondrite-normalized REE value,logarithmic REE value,various REE eigenvalues including scandium,Eu/Sm ratio,total REE amount,light and heavy REEs,δEu,Eu anomaly,Sm/Nd ratio,and silicon isotope δ^(30) SiNBS-29‰,etc.The petrochemical plots include ACMs,100 mg-c-(al+alk),SiO_(2)-(Na_(2)O+K_(2)O),(al+fm)-(c+alk)versus Si,FeO+Fe_(2)O^(3+) TiO)-Al_(2)O_(3)-MgO,c-mg,Al_(2)O_(3)-(Na_(2)O+K_(2)O),chondrite-normalized REE model,La/Yb-REE,and Sm/Nd ratio,etc.On the basis of these comprehensive analyses,the following conclusions are drawn,starting from the many mantle-derived types of basalt developed in the study area of different geological ages,combined with the previously published research results on the deposit s fluid inclusions and sulfur and lead isotopes.The deposit is formed by mantle degassing in the form of a mantle plume in the late Yanshanian orogeny.The degassed fluids are rich in nano-sc ale substances including Fe,Te,S,As,Bi,Au,Se,H_(2),CO_(2),N_(2),H_(2)O,and CH_(4),which are enriched by nano-effect,and then rise to a certain part of the crust in the form of mantle plume along the lithospheric fault to form the deposit.The ultimate power for tellurium mineralization was from H_(2)flow with high energy,which was produced through radiation from the melted iron of the Earth’s outer core.The H,flow results in the Earth’s degassing,as well as the mantle and crust’s uplift.展开更多
BACKGROUND Myocardial bridge(MB)will compress the mural coronary artery(MCA)during the systole and cause myocardial ischemia.In the diagnosis of coronary heart disease(CHD),because the structure of MB is difficult to ...BACKGROUND Myocardial bridge(MB)will compress the mural coronary artery(MCA)during the systole and cause myocardial ischemia.In the diagnosis of coronary heart disease(CHD),because the structure of MB is difficult to be observed by coronary angiography(CAG),the clinical study of the influence of MB on CHD is lacking.With the advancement of computed tomography coronary angiography technology,detailed observations of the MB anatomy have realized.AIM To explore the main influencing factors of MB-related CHD and to find potential indicators for predicting MB-related CHD.METHODS A total of 1718 patients with suspected CHD due to the symptoms of myocardial ischemia were enrolled as subjects.Patients diagnosed with CHD were included in a CHD group,and patients with no significant abnormalities were included in a control group.In the CHD group,patients were divided into an MB-CHD subgroup if MB-related CHD was found.In the control group,patients were divided into a simple MB subgroup if MB was found.The patient's clinical data and MB-related indicators,including the branch of MB,MB type(superficial/deep type),MB length,MB thickness,systolic and diastolic compression of the MCA,and MCA systolic stenosis rate were recorded and compared.Logistic regression analysis was used to explore the independent influencing factors of MD-related CHD.ROC curve was used to analyze the diagnostic efficacy of potential indicators for MB-related CHD.RESULTS There were 1060 cases in the CHD group and 658 cases in the control group,and there were 236 cases in the MB-CHD subgroup and 52 cases in the simple MB subgroup.Multivariate logistic regression analysis showed that the combined MB had a significant effect on the occurrence of CHD(P<0.05).MB thickness,systolic compression,diastolic compression,and MCA systolic stenosis rate had significant effects on the occurrence of MB-related CHD(P<0.05).The area under the curve(AUC)of the combination of these influencing factors for the diagnosis of MB-related CHD was 0.959,which was significantly higher than the AUCs of the four indicators separately(P<0.05).The sensitivity was 97.06%and the specificity was 87.63%.CONCLUSION MB thickness,systolic compression,diastolic compression,and MCA systolic stenosis are independent influencing factors for MB-related CHD.The combination of these factors has potential diagnostic value for MB-related CHD.展开更多
As one branch of spintronics, diluted magnetic semiconductors (DMSs) are extensively investigated due to their fundamental significance and potential application in modern information society. The classical materials ...As one branch of spintronics, diluted magnetic semiconductors (DMSs) are extensively investigated due to their fundamental significance and potential application in modern information society. The classical materials (Ga,Mn)As of III-V group based DMSs has been well studied for its high compatibility with the high-mobility semiconductor GaAs. But the Curie temperature in (Ga,Mn)As film is still far below room temperature because the spin & charge doping is bundled to the same element that makes the fabrication very difficult. Alternatively, the discovery of a new generation DMSs with independent spin and charge doping, such as (Ba,K)(Zn,Mn)2As2 (briefly named BZA), attracted considerable attention due to their unique advantages in physical properties and heterojunction fabrication. In this review we focus on this series of new DMSs including (I) materials in terms of three types of new DMSs, i.e. the "111","122" and "1111" system;(II) the physical properties of BZA;(III) single crystals & prototype device based on BZA. The prospective of new type of DMSs with independent spin and charge doping is briefly discussed.展开更多
The numerical manifold method(NMM)can be viewed as an inherent continuous-discontinuous numerical method,which is based on two cover systems including mathematical and physical covers.Higher-order NMM that adopts high...The numerical manifold method(NMM)can be viewed as an inherent continuous-discontinuous numerical method,which is based on two cover systems including mathematical and physical covers.Higher-order NMM that adopts higher-order polynomials as its local approximations generally shows higher precision than zero-order NMM whose local approximations are constants.Therefore,higherorder NMM will be an excellent choice for crack propagation problem which requires higher stress accuracy.In addition,it is crucial to improve the stress accuracy around the crack tip for determining the direction of crack growth according to the maximum circumferential stress criterion in fracture mechanics.Thus,some other enriched local approximations are introduced to model the stress singularity at the crack tip.Generally,higher-order NMM,especially first-order NMM wherein local approximations are first-order polynomials,has the linear dependence problems as other partition of unit(PUM)based numerical methods does.To overcome this problem,an extended NMM is developed based on a new local approximation derived from the triangular plate element in the finite element method(FEM),which has no linear dependence issue.Meanwhile,the stresses at the nodes of mathematical mesh(the nodal stresses in FEM)are continuous and the degrees of freedom defined on the physical patches are physically meaningful.Next,the extended NMM is employed to solve multiple crack propagation problems.It shows that the fracture mechanics requirement and mechanical equilibrium can be satisfied by the trial-and-error method and the adjustment of the load multiplier in the process of crack propagation.Four numerical examples are illustrated to verify the feasibility of the proposed extended NMM.The numerical examples indicate that the crack growths simulated by the extended NMM are in good accordance with the reference solutions.Thus the effectiveness and correctness of the developed NMM have been validated.展开更多
Since it is unrealistic to do an experimental mixture assessment on every possible combination, mathematical model plays an important role in predicting the mixture toxicity. The present study is devoted to the furthe...Since it is unrealistic to do an experimental mixture assessment on every possible combination, mathematical model plays an important role in predicting the mixture toxicity. The present study is devoted to the further application of linear concentration addition(CA)-based model(LCA) and independent action(IA)-based model(LIA) to predict the non-interactive mixture toxicity. The 26 mixtures including 312 data points were used to evaluate the predictive powers of LCA and LIA models. The models were internally validated using the leave-one-out cross-validation and y-randomization test, and the external validations were evaluated by the test tests. Both LCA and LIA models agree well with the experimental values for all mixture toxicity, and present high internally(R2 and Q2 〉 0.98) and externally(Q2F1, Q2F2, and Q2F3 〉 0.99) predictive power. The use of LCA and LIA led to improved predictions compared to the estimates based on the CA and IA models. Both LCA and LIA were found to be appropriate methods for modeling toxicity of non-interactive chemical mixtures.展开更多
In many batch processes, there are related or independence relationships among process variables. The traditional monitoring method usually carries out a single statistical model according to the related or independen...In many batch processes, there are related or independence relationships among process variables. The traditional monitoring method usually carries out a single statistical model according to the related or independent method, and in the feature extraction there is not fully taken into account the characterization of fault information, it will make the process monitoring ineffective, so a fault monitoring method based on WGNPE(weighted global neighborhood preserving embedding)–GSVDD(greedy support vector data description) related and independent variables is proposed. First, mutual information method is used to separate the related variables and independent variables. Secondly, WGNPE method is used to extract the local and global structures of the related variables in batch process and highlight the fault information, GSVDD method is used to extract the process information of the independent variables quickly and effectively. Finally, the statistical monitoring model is established to achieve process monitoring based on WGNPE and GSVDD. The effectiveness of the proposed method was verified by the penicillin fermentation process.展开更多
Purpose To explore the needs for basic community-based rehabilitation services for disabled persons in Xuanwu District, Beijing, China, and to identify factors which influence disabled persons to accept rehabilitation...Purpose To explore the needs for basic community-based rehabilitation services for disabled persons in Xuanwu District, Beijing, China, and to identify factors which influence disabled persons to accept rehabilitation services. Method One hundred and eight disabled persons were selected by systematic sampling and simple random sampling to assess their needs for community-based rehabilitation services. Results Of the interviewees, 57A% needed the community-based rehabilitation services, but only 13.9% took advantage of it. The main factors influencing the interviewees to accept these services were cost (P〈0.05), knowledge about rehabilitation medicine (P〈0.05); and the belief in the therapeutic benefit of the community-based rehabilitation service (P〈0.05). Conclusion A considerable gap exists between the supply of community-based rehabilitation services in Beijing and the needs for these services by disabled residents underscoring the need for improved availability, and for additional research.展开更多
We propose an ultra-broadband and polarization independent planar absorber comprising multilayered graphene. The bandwidth of the proposed absorber is extended by increasing the number of layers of graphene, and it is...We propose an ultra-broadband and polarization independent planar absorber comprising multilayered graphene. The bandwidth of the proposed absorber is extended by increasing the number of layers of graphene, and it is polarization independent due to its symmetrical unit structure. The full wave simulation results show that an absorber with three graphenebased layers can efficiently harvest an electromagnetic wave with random polarization from 17.9 GHz to 188.7 GHz(i.e.,covering frequency regimes from K to D bands and relative bandwidth of - 165%). The physical absorption mechanism of ultra-broadband absorption has been elaborated upon using the destructive interference method and multiple resonances approach in a multilayered medium. The proposed absorber can be used in many applications such as medical treatment,electromagnetic compatibility, and stealth technique.展开更多
Highly hydrophilic materials enable rapid water delivery and salt redissolution in solar-driven seawater desalination. However, the lack of independent floatability inhibits heat localization at the air/water interfac...Highly hydrophilic materials enable rapid water delivery and salt redissolution in solar-driven seawater desalination. However, the lack of independent floatability inhibits heat localization at the air/water interface. In nature, seaweeds with internal gas microvesicles can float near the sea surface to ensure photosynthesis. Here, we have developed a seaweed-inspired, independently floatable, but superhydrophilic (SIFS) solar evaporator. It needs no extra floatation support and can simultaneously achieve continuous water pumping and heat concentration. The evaporator resists salt accumulation, oil pollution, microbial corrosion, and protein adsorption. Densely packed hollow glass microbeads promote intrinsic floatability and heat insulation. Superhydrophilic zwitterionic sulfobetaine hydrogel provides a continuous water supply, redissolves the deposited salt, and endows the SIFS evaporator with excellent anti-fouling properties. With its unprecedented anti-contamination ability, this SIFS evaporator is expected to open a new avenue for designing floatable superhydrophilic materials and solving real-world issues of solar steam generation in complex environmental conditions.展开更多
This paper presents a concurrent dual-band branch-line coupler with an independently tunable center frequency. In the proposed architecture, the quarter-wavelength lines, which work at two separated bands concurrently...This paper presents a concurrent dual-band branch-line coupler with an independently tunable center frequency. In the proposed architecture, the quarter-wavelength lines, which work at two separated bands concurrently and can be tuned in one of them, are key components. Based on the analysis of ABCD-matrix, a novel hybrid structure and a pair of varactors topology are utilized to achieve concurrent dual-band operation and independent tunability, respectively. Using this configuration, it is convenient to tune the center frequency of the upper band, while the responses of the lower band remain unaltered. To verify the proposed idea, a demonstration is implemented and the simulated results are presented.展开更多
A new method was developed for batch process monitoring in this paper.In the developed method,just-in-time learning(J1TL) and independent component analysis(ICA) were integrated to build JITL-ICA monitoring scheme.JIT...A new method was developed for batch process monitoring in this paper.In the developed method,just-in-time learning(J1TL) and independent component analysis(ICA) were integrated to build JITL-ICA monitoring scheme.JITL was employed to tackle with the characteristics of batch process such as inherent timevarying dynamics,multiple operating phases,and especially the case of uneven length stage.According to new coming test data,the most correlated segmentation was obtained from batch-wise unfolded training data by JITL.Then,ICA served as the principal components extraction approach.Therefore,the non-Gaussian distributed data can also be addressed under this modeling framework.The effectiveness and superiority of JITL-ICA based monitoring method was demonstrated by fed-batch penicillin fermentation.展开更多
Fatigue failure is a common failure mode under the action of cyclic loads in engineering applications,which often occurs with no obvious signal.The maximum structural stress is far below the allowable stress when the ...Fatigue failure is a common failure mode under the action of cyclic loads in engineering applications,which often occurs with no obvious signal.The maximum structural stress is far below the allowable stress when the structures are damaged.Aiming at the lightweight structure,fatigue topology optimization design is investigated to avoid the occurrence of fatigue failure in the structural conceptual design beforehand.Firstly,the fatigue life is expressed by topology variables and the fatigue life filter function.The continuum fatigue optimization model is established with the independent continuous mapping(ICM)method.Secondly,fatigue life constraints are transformed to distortion energy constraints explicitly by taking advantage of the distortion energy theory.Thirdly,the optimization formulation is solved by the dual sequence quadratic programming(DSQP).And the design scheme of lightweight structure considering the fatigue characteristics is obtained.Finally,numerical examples illustrate the practicality and effectiveness of the fatigue optimization method.This method further expands the theoretical application of the ICM method and provides a novel approach for the fatigue optimization problem.展开更多
BACKGROUND Our study expand upon a large body of evidence in the field of neuropsychiatric imaging with cognitive,affective and behavioral tasks,adapted for the functional magnetic resonance imaging(MRI)(fMRI)experime...BACKGROUND Our study expand upon a large body of evidence in the field of neuropsychiatric imaging with cognitive,affective and behavioral tasks,adapted for the functional magnetic resonance imaging(MRI)(fMRI)experimental environment.There is sufficient evidence that common networks underpin activations in task-based fMRI across different mental disorders.AIM To investigate whether there exist specific neural circuits which underpin differ-ential item responses to depressive,paranoid and neutral items(DN)in patients respectively with schizophrenia(SCZ)and major depressive disorder(MDD).METHODS 60 patients were recruited with SCZ and MDD.All patients have been scanned on 3T magnetic resonance tomography platform with functional MRI paradigm,comprised of block design,including blocks with items from diagnostic paranoid(DP),depression specific(DS)and DN from general interest scale.We performed a two-sample t-test between the two groups-SCZ patients and depressive patients.Our purpose was to observe different brain networks which were activated during a specific condition of the task,respectively DS,DP,DN.RESULTS Several significant results are demonstrated in the comparison between SCZ and depressive groups while performing this task.We identified one component that is task-related and independent of condition(shared between all three conditions),composed by regions within the temporal(right superior and middle temporal gyri),frontal(left middle and inferior frontal gyri)and limbic/salience system(right anterior insula).Another com-ponent is related to both diagnostic specific conditions(DS and DP)e.g.It is shared between DEP and SCZ,and includes frontal motor/language and parietal areas.One specific component is modulated preferentially by to the DP condition,and is related mainly to prefrontal regions,whereas other two components are significantly modulated with the DS condition and include clusters within the default mode network such as posterior cingulate and precuneus,several occipital areas,including lingual and fusiform gyrus,as well as parahippocampal gyrus.Finally,component 12 appeared to be unique for the neutral condition.In addition,there have been determined circuits across components,which are either common,or distinct in the preferential processing of the sub-scales of the task.CONCLUSION This study has delivers further evidence in support of the model of trans-disciplinary cross-validation in psychiatry.展开更多
基金Support for this study was received from Orient Resources Ltd.in Canada,Wuhan Institute of Technology,China,and College of Earth Sciences,Jilin University,China.
文摘By studying the light isotopic compositions of carbon,oxygen,and hydrogen,combined with previous research results on the ore-forming source of the deposit,the authors try to uncover its metallogenic origin.The δ^(18)O and δ^(13)C isotope signatures of dolomite samples vary between 10.2 and 13.0‰,and between−7.2 and−5.2‰,respectively,implying that the carbon derives from the upper mantle.δD and δ^(18) O of quartz,biotite,and muscovite from diff erent ore veins of the deposit vary between−82 and−59‰,and between 11.6 and 12.4‰,respectively,implying that the metallogenic solutions are mainly magmatic.According to the relevant research results of many isotope geologists,the fractionation degree of hydrogen isotopes increases as the depth to the Earth’s core increases,and the more diff erentiated the hydrogen isotopes are,the lower their values will be.In other words,mantle-derived solutions can have extremely low hydrogen isotope values.This means that the δD‰ value−134 of the pyrrhotite sample numbered SD-34 in this article may indicate mantle-derived oreforming fl uid of the deposit.The formation of the Dashuigou tellurium deposit occurred between 91.71 and 80.19 Ma.
文摘In this paper, we consider the relationship between the binding number and the existence of fractional k-factors of graphs. The binding number of G is defined by Woodall as bind(G)=min{ | NG(X) || X |:∅≠X⊆V(G) }. It is proved that a graph G has a fractional 1-factor if bind(G)≥1and has a fractional k-factor if bind(G)≥k−1k. Furthermore, it is showed that both results are best possible in some sense.
基金supported by the National SKA Program of China (2022SKA0130100)the National Natural Science Foundation of China (Grant Nos. 12373053, 12321003, and 12041306)+4 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences (Grant No. ZDBSLY-7014)the International Partnership Program of Chinese Academy of Sciences for Grand Challenges (Grant No. 114332KYSB20210018)the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-063)the CAS Organizational Scientific Research Platform for National Major Scientific and Technological Infrastructure: Cosmic Transients with FASTthe Natural Science Foundation of Jiangsu Province (Grant No. BK20221562)。
文摘A hypothetical photon mass m_(γ) can produce a frequency-dependent vacuum dispersion of light, which leads to an additional time delay between photons with different frequencies when they propagate through a fixed distance. The dispersion measure and redshift measurements of fast radio bursts(FRBs) have been widely used to constrain the rest mass of the photon. However, all current studies analyzed the effect of the frequency-dependent dispersion for massive photons in the standard ΛCDM cosmological context. In order to alleviate the circularity problem induced by the presumption of a specific cosmological model based on the fundamental postulate of the masslessness of photons, here we employ a new model-independent smoothing technique, artificial neural network(ANN), to reconstruct the Hubble parameter H(z) function from 34 cosmic-chronometer measurements.By combining observations of 32 well-localized FRBs and the H(z) function reconstructed by ANN, we obtain an upper limit of m_(γ) ≤ 3.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 2.0 × 10^(-15)eV/c^(2)(m_(γ) ≤ 6.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 3.6 × 10^(-15)eV/c_(2)) at the 1σ(2σ) confidence level. This is the first cosmology-independent photon mass limit derived from extragalactic sources.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975118,52025121)Foundation of State Key Laboratory of Automotive Simulation and Control of China(Grant No.20210104)+1 种基金Foundation of State Key Laboratory of Automobile Safety and Energy Saving of China(Grant No.KFZ2201)Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements of China(Grant No.BA2021023).
文摘Four-wheel independently driven electric vehicles(FWID-EV)endow a flexible and scalable control framework to improve vehicle performance.This paper integrates the torque vectoring and active suspension system(ASS)to enhance the vehicle’s longitudinal and vertical motion control performance.While the nonlinear characteristic of the tire model leads to a relatively heavier computational burden.To facilitate the controller design and ease the load,a half-vehicle dynamics system is built and simplified to the linear-time-varying(LTV)model.Then a model predictive controller is developed by formulating the objective function by comprehensively considering the safety,energy-saving and comfort requirements.The in-wheel motor efficiency and the power loss of tire slip are treated as optimization indices in this work to reduce energy consumption.Finally,the effectiveness of the proposed controller is verified through the rapid-control-prototype(RCP)test.The results demonstrate the enhancement of the energy-saving as well as comfort on the basis of vehicle stability.
基金supported in part by National Natural Science Foundation of China(NSFC)under Project No.51737010.
文摘The most critical obstacle for four-wheel independently driven electric vehicles(4WID-EVs)is the driving range.Being the actuators of 4WID-EVs,motors account for its major power consumption.In this sense,by properly distributing torques to minimize the power consumption,the driving range of 4WID-EV can be effectively improved.This paper proposes a model predictive control(MPC)-based torque distribution scheme,which minimizes the power consumption of 4WID-EVs while guaranteeing its tracking performance of planar motions.By incorporating the motor model considering iron losses,the optimal torque distribution can be achieved without an additional torque controller.Also,for this reason,the proposed control scheme is computationally efficient,since the power consumption term to be optimized,which is expressed as the product of the motor voltages and currents,is much simpler than that derived from the efficiency map.With reasonable simplification and linearization,the MPC problem is converted to a quadratic programming problem,which can be solved efficiently.The simulation results in MATLAB and CarSim co-simulation environments demonstrate that the proposed scheme effectively reduces power consumption with guaranteed tracking performance.
文摘As an effort to understand the effect of diabetes on the increasing rate of COVID-19 infection, we embarked upon a detailed statistical analysis of various datasets that include COVID-19 infection and mortality rate, diabetes and diseases that may contribute to the severity and risk factor of diabetes in individuals and this impact on COVID-19 and the mortality rate. These diseases include respiratory diseases, cardiovascular diseases, and obesity. Equally significant is the statistical analysis on ethnicity, age, and sex on COVID-19 infection as well as mortality rate. Their possible contributions to increasing the severity and risk factor of diabetes as a risk to mortality to individuals who have COVID-19. Objectives: The ultimate objectives of this investigation are as follow: 1) Is there a risk factor of diabetes on COVID-19 infection and increasing mortality rate? 2) To what extent do other disease conditions that include, obesity, heart failure, and respiratory diseases influence the severity and risk factor of diabetes on increasing COVID-19 infection and mortality rate? 3) To what extent does age, race, and gender increase the mortality of COVID-19 and increase the severity and risk factor of diabetes on COVID-19 mortality rate? 4) How and why COVID-19 virus increases the risk of diabetes in children? 5) Diabetes and COVID-19: Who is most at Risk? Lastly, understanding the misconception of COVID-19 and diabetes.
基金supported by Orient Resources Ltd.College of Earth Sciences,Jilin University。
文摘The Dashuigou tellurium deposit is the world’s only known independent tellurium deposit.By restoring metamorphic rocks’protolith,we seek to understand not only the development and evolution trajectory of the region but also the origin of the relevant deposits.While there are many ways to restore metamorphic rocks’protolith,we take the host metamorphic rocks of Dashuigou tellurium deposit and leverage various petrochemical eigenvalues and related diagrams previously proposed to reveal the deposit’s host metamorphic rocks’protolith.The petrochemical eigenvalues include molecular number,Niggli’s value,REE parity ratio,CaO/Al_(2)O_(3)ratio,Fe^(3+) /(Fe^(3+) -+Fe^(2+) )ratio,chondrite-normalized REE value,logarithmic REE value,various REE eigenvalues including scandium,Eu/Sm ratio,total REE amount,light and heavy REEs,δEu,Eu anomaly,Sm/Nd ratio,and silicon isotope δ^(30) SiNBS-29‰,etc.The petrochemical plots include ACMs,100 mg-c-(al+alk),SiO_(2)-(Na_(2)O+K_(2)O),(al+fm)-(c+alk)versus Si,FeO+Fe_(2)O^(3+) TiO)-Al_(2)O_(3)-MgO,c-mg,Al_(2)O_(3)-(Na_(2)O+K_(2)O),chondrite-normalized REE model,La/Yb-REE,and Sm/Nd ratio,etc.On the basis of these comprehensive analyses,the following conclusions are drawn,starting from the many mantle-derived types of basalt developed in the study area of different geological ages,combined with the previously published research results on the deposit s fluid inclusions and sulfur and lead isotopes.The deposit is formed by mantle degassing in the form of a mantle plume in the late Yanshanian orogeny.The degassed fluids are rich in nano-sc ale substances including Fe,Te,S,As,Bi,Au,Se,H_(2),CO_(2),N_(2),H_(2)O,and CH_(4),which are enriched by nano-effect,and then rise to a certain part of the crust in the form of mantle plume along the lithospheric fault to form the deposit.The ultimate power for tellurium mineralization was from H_(2)flow with high energy,which was produced through radiation from the melted iron of the Earth’s outer core.The H,flow results in the Earth’s degassing,as well as the mantle and crust’s uplift.
文摘BACKGROUND Myocardial bridge(MB)will compress the mural coronary artery(MCA)during the systole and cause myocardial ischemia.In the diagnosis of coronary heart disease(CHD),because the structure of MB is difficult to be observed by coronary angiography(CAG),the clinical study of the influence of MB on CHD is lacking.With the advancement of computed tomography coronary angiography technology,detailed observations of the MB anatomy have realized.AIM To explore the main influencing factors of MB-related CHD and to find potential indicators for predicting MB-related CHD.METHODS A total of 1718 patients with suspected CHD due to the symptoms of myocardial ischemia were enrolled as subjects.Patients diagnosed with CHD were included in a CHD group,and patients with no significant abnormalities were included in a control group.In the CHD group,patients were divided into an MB-CHD subgroup if MB-related CHD was found.In the control group,patients were divided into a simple MB subgroup if MB was found.The patient's clinical data and MB-related indicators,including the branch of MB,MB type(superficial/deep type),MB length,MB thickness,systolic and diastolic compression of the MCA,and MCA systolic stenosis rate were recorded and compared.Logistic regression analysis was used to explore the independent influencing factors of MD-related CHD.ROC curve was used to analyze the diagnostic efficacy of potential indicators for MB-related CHD.RESULTS There were 1060 cases in the CHD group and 658 cases in the control group,and there were 236 cases in the MB-CHD subgroup and 52 cases in the simple MB subgroup.Multivariate logistic regression analysis showed that the combined MB had a significant effect on the occurrence of CHD(P<0.05).MB thickness,systolic compression,diastolic compression,and MCA systolic stenosis rate had significant effects on the occurrence of MB-related CHD(P<0.05).The area under the curve(AUC)of the combination of these influencing factors for the diagnosis of MB-related CHD was 0.959,which was significantly higher than the AUCs of the four indicators separately(P<0.05).The sensitivity was 97.06%and the specificity was 87.63%.CONCLUSION MB thickness,systolic compression,diastolic compression,and MCA systolic stenosis are independent influencing factors for MB-related CHD.The combination of these factors has potential diagnostic value for MB-related CHD.
基金financially supported by Ministry of Science and Technology of China (Nos. 2018YFA03057001, and 2017YFB0405703)National Natural Science Foundation of China through the research projects (No. 11534016)
文摘As one branch of spintronics, diluted magnetic semiconductors (DMSs) are extensively investigated due to their fundamental significance and potential application in modern information society. The classical materials (Ga,Mn)As of III-V group based DMSs has been well studied for its high compatibility with the high-mobility semiconductor GaAs. But the Curie temperature in (Ga,Mn)As film is still far below room temperature because the spin & charge doping is bundled to the same element that makes the fabrication very difficult. Alternatively, the discovery of a new generation DMSs with independent spin and charge doping, such as (Ba,K)(Zn,Mn)2As2 (briefly named BZA), attracted considerable attention due to their unique advantages in physical properties and heterojunction fabrication. In this review we focus on this series of new DMSs including (I) materials in terms of three types of new DMSs, i.e. the "111","122" and "1111" system;(II) the physical properties of BZA;(III) single crystals & prototype device based on BZA. The prospective of new type of DMSs with independent spin and charge doping is briefly discussed.
基金supported by the National Key R&D Program of China (Grant No.2018YFC0407002)the National Natural Science Foundation of China(Grant Nos.11502033 and 51879014)
文摘The numerical manifold method(NMM)can be viewed as an inherent continuous-discontinuous numerical method,which is based on two cover systems including mathematical and physical covers.Higher-order NMM that adopts higher-order polynomials as its local approximations generally shows higher precision than zero-order NMM whose local approximations are constants.Therefore,higherorder NMM will be an excellent choice for crack propagation problem which requires higher stress accuracy.In addition,it is crucial to improve the stress accuracy around the crack tip for determining the direction of crack growth according to the maximum circumferential stress criterion in fracture mechanics.Thus,some other enriched local approximations are introduced to model the stress singularity at the crack tip.Generally,higher-order NMM,especially first-order NMM wherein local approximations are first-order polynomials,has the linear dependence problems as other partition of unit(PUM)based numerical methods does.To overcome this problem,an extended NMM is developed based on a new local approximation derived from the triangular plate element in the finite element method(FEM),which has no linear dependence issue.Meanwhile,the stresses at the nodes of mathematical mesh(the nodal stresses in FEM)are continuous and the degrees of freedom defined on the physical patches are physically meaningful.Next,the extended NMM is employed to solve multiple crack propagation problems.It shows that the fracture mechanics requirement and mechanical equilibrium can be satisfied by the trial-and-error method and the adjustment of the load multiplier in the process of crack propagation.Four numerical examples are illustrated to verify the feasibility of the proposed extended NMM.The numerical examples indicate that the crack growths simulated by the extended NMM are in good accordance with the reference solutions.Thus the effectiveness and correctness of the developed NMM have been validated.
基金supported by the National Natural Science Foundation of China(21407032,21667013,51578171)Natural Science Foundation of Guangxi Province(2014GXNSFBA118233)Guilin Scientific Research and Technology Development Program(2016012505)
文摘Since it is unrealistic to do an experimental mixture assessment on every possible combination, mathematical model plays an important role in predicting the mixture toxicity. The present study is devoted to the further application of linear concentration addition(CA)-based model(LCA) and independent action(IA)-based model(LIA) to predict the non-interactive mixture toxicity. The 26 mixtures including 312 data points were used to evaluate the predictive powers of LCA and LIA models. The models were internally validated using the leave-one-out cross-validation and y-randomization test, and the external validations were evaluated by the test tests. Both LCA and LIA models agree well with the experimental values for all mixture toxicity, and present high internally(R2 and Q2 〉 0.98) and externally(Q2F1, Q2F2, and Q2F3 〉 0.99) predictive power. The use of LCA and LIA led to improved predictions compared to the estimates based on the CA and IA models. Both LCA and LIA were found to be appropriate methods for modeling toxicity of non-interactive chemical mixtures.
基金Supported by the National Natural Science Foundation of China(No.61763029)the Natural Science Foundation of Gansu Province(1610RJZA016)
文摘In many batch processes, there are related or independence relationships among process variables. The traditional monitoring method usually carries out a single statistical model according to the related or independent method, and in the feature extraction there is not fully taken into account the characterization of fault information, it will make the process monitoring ineffective, so a fault monitoring method based on WGNPE(weighted global neighborhood preserving embedding)–GSVDD(greedy support vector data description) related and independent variables is proposed. First, mutual information method is used to separate the related variables and independent variables. Secondly, WGNPE method is used to extract the local and global structures of the related variables in batch process and highlight the fault information, GSVDD method is used to extract the process information of the independent variables quickly and effectively. Finally, the statistical monitoring model is established to achieve process monitoring based on WGNPE and GSVDD. The effectiveness of the proposed method was verified by the penicillin fermentation process.
基金This research got support by Beijing Education Committee as a key-point project on humanities and social sciences (Grant No. SZ200410025005).
文摘Purpose To explore the needs for basic community-based rehabilitation services for disabled persons in Xuanwu District, Beijing, China, and to identify factors which influence disabled persons to accept rehabilitation services. Method One hundred and eight disabled persons were selected by systematic sampling and simple random sampling to assess their needs for community-based rehabilitation services. Results Of the interviewees, 57A% needed the community-based rehabilitation services, but only 13.9% took advantage of it. The main factors influencing the interviewees to accept these services were cost (P〈0.05), knowledge about rehabilitation medicine (P〈0.05); and the belief in the therapeutic benefit of the community-based rehabilitation service (P〈0.05). Conclusion A considerable gap exists between the supply of community-based rehabilitation services in Beijing and the needs for these services by disabled residents underscoring the need for improved availability, and for additional research.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61661012,61461016,61361005,and 61561013)the Natural Science Foundation of Guangxi,China(Grant No.2017JJB160028)+1 种基金the Program for Innovation Research Team of Guilin University of Electronic Technology,Chinathe Dean Project of Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing,China
文摘We propose an ultra-broadband and polarization independent planar absorber comprising multilayered graphene. The bandwidth of the proposed absorber is extended by increasing the number of layers of graphene, and it is polarization independent due to its symmetrical unit structure. The full wave simulation results show that an absorber with three graphenebased layers can efficiently harvest an electromagnetic wave with random polarization from 17.9 GHz to 188.7 GHz(i.e.,covering frequency regimes from K to D bands and relative bandwidth of - 165%). The physical absorption mechanism of ultra-broadband absorption has been elaborated upon using the destructive interference method and multiple resonances approach in a multilayered medium. The proposed absorber can be used in many applications such as medical treatment,electromagnetic compatibility, and stealth technique.
基金supported by the National Natural Science Foundation of China(21621004,21961132005,22078238,21908160,and 21805204)the Tianjin Natural Science Foundation(19JCQNJC05100 and 20JCQNJC00170)+1 种基金Young Elite Scientists Sponsorship Program by Tianjin(TJSQNTJ-2018-17)the China Postdoctoral Science Foundation(2019M651041).
文摘Highly hydrophilic materials enable rapid water delivery and salt redissolution in solar-driven seawater desalination. However, the lack of independent floatability inhibits heat localization at the air/water interface. In nature, seaweeds with internal gas microvesicles can float near the sea surface to ensure photosynthesis. Here, we have developed a seaweed-inspired, independently floatable, but superhydrophilic (SIFS) solar evaporator. It needs no extra floatation support and can simultaneously achieve continuous water pumping and heat concentration. The evaporator resists salt accumulation, oil pollution, microbial corrosion, and protein adsorption. Densely packed hollow glass microbeads promote intrinsic floatability and heat insulation. Superhydrophilic zwitterionic sulfobetaine hydrogel provides a continuous water supply, redissolves the deposited salt, and endows the SIFS evaporator with excellent anti-fouling properties. With its unprecedented anti-contamination ability, this SIFS evaporator is expected to open a new avenue for designing floatable superhydrophilic materials and solving real-world issues of solar steam generation in complex environmental conditions.
基金Supported by the Provincial Natural Science Foundation of Zhejiang(No.Y1101270)the National Natural Science Foundation of China(No.61171040)+1 种基金Ningbo University Disciplinary Project(No.XKL141038)Agilent Technologies Inc.Research Project(No.3110)
文摘This paper presents a concurrent dual-band branch-line coupler with an independently tunable center frequency. In the proposed architecture, the quarter-wavelength lines, which work at two separated bands concurrently and can be tuned in one of them, are key components. Based on the analysis of ABCD-matrix, a novel hybrid structure and a pair of varactors topology are utilized to achieve concurrent dual-band operation and independent tunability, respectively. Using this configuration, it is convenient to tune the center frequency of the upper band, while the responses of the lower band remain unaltered. To verify the proposed idea, a demonstration is implemented and the simulated results are presented.
基金National Natural Science Foundations of China(Nos.61403256,61374132)Special Scientific Research of Selection and Cultivation of Excellent Young Teachers in Shanghai Universities,China(No.YYY11076)
文摘A new method was developed for batch process monitoring in this paper.In the developed method,just-in-time learning(J1TL) and independent component analysis(ICA) were integrated to build JITL-ICA monitoring scheme.JITL was employed to tackle with the characteristics of batch process such as inherent timevarying dynamics,multiple operating phases,and especially the case of uneven length stage.According to new coming test data,the most correlated segmentation was obtained from batch-wise unfolded training data by JITL.Then,ICA served as the principal components extraction approach.Therefore,the non-Gaussian distributed data can also be addressed under this modeling framework.The effectiveness and superiority of JITL-ICA based monitoring method was demonstrated by fed-batch penicillin fermentation.
基金This work was supported by the National Natural Science Foundation of China(11872080)Beijing Natural Science Foundation(3192005).
文摘Fatigue failure is a common failure mode under the action of cyclic loads in engineering applications,which often occurs with no obvious signal.The maximum structural stress is far below the allowable stress when the structures are damaged.Aiming at the lightweight structure,fatigue topology optimization design is investigated to avoid the occurrence of fatigue failure in the structural conceptual design beforehand.Firstly,the fatigue life is expressed by topology variables and the fatigue life filter function.The continuum fatigue optimization model is established with the independent continuous mapping(ICM)method.Secondly,fatigue life constraints are transformed to distortion energy constraints explicitly by taking advantage of the distortion energy theory.Thirdly,the optimization formulation is solved by the dual sequence quadratic programming(DSQP).And the design scheme of lightweight structure considering the fatigue characteristics is obtained.Finally,numerical examples illustrate the practicality and effectiveness of the fatigue optimization method.This method further expands the theoretical application of the ICM method and provides a novel approach for the fatigue optimization problem.
文摘BACKGROUND Our study expand upon a large body of evidence in the field of neuropsychiatric imaging with cognitive,affective and behavioral tasks,adapted for the functional magnetic resonance imaging(MRI)(fMRI)experimental environment.There is sufficient evidence that common networks underpin activations in task-based fMRI across different mental disorders.AIM To investigate whether there exist specific neural circuits which underpin differ-ential item responses to depressive,paranoid and neutral items(DN)in patients respectively with schizophrenia(SCZ)and major depressive disorder(MDD).METHODS 60 patients were recruited with SCZ and MDD.All patients have been scanned on 3T magnetic resonance tomography platform with functional MRI paradigm,comprised of block design,including blocks with items from diagnostic paranoid(DP),depression specific(DS)and DN from general interest scale.We performed a two-sample t-test between the two groups-SCZ patients and depressive patients.Our purpose was to observe different brain networks which were activated during a specific condition of the task,respectively DS,DP,DN.RESULTS Several significant results are demonstrated in the comparison between SCZ and depressive groups while performing this task.We identified one component that is task-related and independent of condition(shared between all three conditions),composed by regions within the temporal(right superior and middle temporal gyri),frontal(left middle and inferior frontal gyri)and limbic/salience system(right anterior insula).Another com-ponent is related to both diagnostic specific conditions(DS and DP)e.g.It is shared between DEP and SCZ,and includes frontal motor/language and parietal areas.One specific component is modulated preferentially by to the DP condition,and is related mainly to prefrontal regions,whereas other two components are significantly modulated with the DS condition and include clusters within the default mode network such as posterior cingulate and precuneus,several occipital areas,including lingual and fusiform gyrus,as well as parahippocampal gyrus.Finally,component 12 appeared to be unique for the neutral condition.In addition,there have been determined circuits across components,which are either common,or distinct in the preferential processing of the sub-scales of the task.CONCLUSION This study has delivers further evidence in support of the model of trans-disciplinary cross-validation in psychiatry.