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The AMS measurement of ^236U at CIRCE 被引量:1
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作者 Yong-Jing Guan Hui-Juan Wang +1 位作者 Mario De Cesare Filippo Terrasi 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第7期47-51,共5页
Accelerator mass spectrometry(AMS) is an ultrasensitive technique for measuring long-lived actinides,e.g.,^(236)U,^(237)Np and Pu isotopes.In order to improve the detection limit for actinides abundance,and to increas... Accelerator mass spectrometry(AMS) is an ultrasensitive technique for measuring long-lived actinides,e.g.,^(236)U,^(237)Np and Pu isotopes.In order to improve the detection limit for actinides abundance,and to increase the detection efficiency in actinides AMS measurement,a 16-strip silicon detector was used to identify actinides at the Center for Isotopic Research on Cultural and Environmental heritage in Caserta,Italy.The sensitivity of ^(236)U/^(238)U was 1×10^(-11) by special resolution and 5.0×10^(-12) by time resolution.The pulse height defect of^(236)U in an ion-implanted silicon detector in the low-energy range with 17.26 MeV is presented. 展开更多
关键词 AMS 测量 锕系元素 钚同位素 硅探测器 加速器质谱 时间分辨率 元素丰度
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STUDY ON THE METEOROLOGICAL PREDICTION MODEL USING THE LEARNING ALGORITHM OF NEURAL ENSEMBLE BASED ON PSO ALGORITHMS 被引量:4
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作者 吴建生 金龙 《Journal of Tropical Meteorology》 SCIE 2009年第1期83-88,共6页
Because of the difficulty in deciding on the structure of BP neural network in operational meteorological application and the tendency for the network to transform to an issue of local solution, a hybrid Particle Swar... Because of the difficulty in deciding on the structure of BP neural network in operational meteorological application and the tendency for the network to transform to an issue of local solution, a hybrid Particle Swarm Optimization Algorithm based on Artificial Neural Network (PSO-BP) model is proposed for monthly mean rainfall of the whole area of Guangxi. It combines Particle Swarm Optimization (PSO) with BP, that is, the number of hidden nodes and connection weights are optimized by the implementation of PSO operation. The method produces a better network architecture and initial connection weights, trains the traditional backward propagation again by training samples. The ensemble strategy is carried out for the linear programming to calculate the best weights based on the "east sum of the error absolute value" as the optimal rule. The weighted coefficient of each ensemble individual is obtained. The results show that the method can effectively improve learning and generalization ability of the neural network. 展开更多
关键词 neural network ensemble particle swarm optimization optimal combination
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QUASI-SURE CONVERGENCE RATE OF EULER SCHEME FOR STOCHASTIC DIFFERENTIAL EQUATIONS 被引量:1
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作者 黄文亮 张希承 《Acta Mathematica Scientia》 SCIE CSCD 2014年第1期65-72,共8页
Let Xt(x) be the solution of stochastic differential equations with smooth and bounded derivatives coefficients. Let Xnt (x) be the Euler discretization scheme of SDEs with step 2-n . In this note, we prove that f... Let Xt(x) be the solution of stochastic differential equations with smooth and bounded derivatives coefficients. Let Xnt (x) be the Euler discretization scheme of SDEs with step 2-n . In this note, we prove that for any R〉0 and γ∈(0, 1/2), sup t∈[0,1],|x|≤R|X nt (x,ω)-Xt (x,ω)|≤ξR,γ(ω)2-nγ, n≥1, q.e., whereξR,γ(ω) is quasi-everywhere finite. 展开更多
关键词 Euler approximation quasi-sure convergence SDE
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A Control of Uncertain Nonlinear Systems with Unknown Control Direction Via Adaptive Backstepping
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作者 郑兆顺 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2007年第2期276-281,共6页
The adaptive stabilization problem of nonlinear systems are studied. For a class of uncertain nonlinear systems with unknown control direction, we proposed a robust adaptive backstepping scheme withσ-modification by ... The adaptive stabilization problem of nonlinear systems are studied. For a class of uncertain nonlinear systems with unknown control direction, we proposed a robust adaptive backstepping scheme withσ-modification by introducing Nussbaum function and Backstep- ping methods, and proved that all the signals of the closed-loop systems are bounded. 展开更多
关键词 nonlinear system adaptive control BACKSTEPPING unknown control direction
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Theoretical analysis of ion kinetic energies and DLC film deposition by CH4+ Ar (He) dielectric barrier discharge plasmas
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作者 刘艳红 张家良 +2 位作者 马腾才 李建 刘东平 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第9期2809-2813,共5页
The kinetic energy of ions in dielectric barrier discharge plasmas are analysed theoretically using the model of binary collisions between ions and gas molecules. Langevin equation for ions in other gases, Blanc law f... The kinetic energy of ions in dielectric barrier discharge plasmas are analysed theoretically using the model of binary collisions between ions and gas molecules. Langevin equation for ions in other gases, Blanc law for ions in mixed gases, and the two-temperature model for ions at higher reduced field are used to determine the ion mobility. The kinetic energies of ions in CH4 + Ar(He) dielectric barrier discharge plasma at a fixed total gas pressure and various Ar (He) concentrations are calculated. It is found that with increasing Ar (He) concentration in CH4 + Ar (He) from 20% to 83%, the CH4+ kinetic energy increases from 69.6 (43.9) to 92.1 (128.5)eV, while the Ar+ (He+) kinetic energy decreases from 97 (145.2) to 78.8 (75.5)eV. The increase of CH4+ kinetic energy is responsible for the increase of hardness of diamond-like carbon films deposited by CH4 + Ar (He) dielectric barrier discharge without bias voltage over substrates. 展开更多
关键词 ion energy dielectric barrier discharge diamond-like carbon deposition
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Resonant Acceleration of Electrons in Combined Self-Consistent Quasistatic Electromagnetic Fields and Intense Laser Fields
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作者 陈奋策 贺贤土 +2 位作者 盛正卯 乔宾 张宏 《Chinese Physics Letters》 SCIE CAS CSCD 2006年第11期3010-3013,共4页
Using the single electron model, the acceleration of electrons in combined circularly polarized intense laser fields and the spontaneous quasistatic fields (including axial and azimuthal magnetic fields, the axial an... Using the single electron model, the acceleration of electrons in combined circularly polarized intense laser fields and the spontaneous quasistatic fields (including axial and azimuthal magnetic fields, the axial and transverse electric fields) produced in intense laser plasma interaction is investigated analytically and numerically by fitting the proper parameters of the quasistatic fields based on the data from the experiment and numerical calculation. A new resonant condition is given. It is found that the resonance acceleration of electron depends not only on laser field, but also on the bounce frequency oscillating in the quasistatic magnetic field and electric field. The net energy gained by electron does not increase monotonously with axial electric field, but there are some optimal axial electric fields. 展开更多
关键词 MAGNETIC-FIELDS PLASMA MODEL
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A Characterization of Complex Projective Spaces by Sections of Line Bundles
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作者 Shuyu Liang Yanan Gao Yicai Zhao 《Advances in Pure Mathematics》 2015年第8期450-453,共4页
Let M be a n-dimensional compact irreducible complex space with a line bundle L. It is shown that if M is completely intersected with respect to L and dimH0(M, L) = n + 1, then M is biholomorphic to a complex projecti... Let M be a n-dimensional compact irreducible complex space with a line bundle L. It is shown that if M is completely intersected with respect to L and dimH0(M, L) = n + 1, then M is biholomorphic to a complex projective space Pn of dimension n. 展开更多
关键词 Complex SPACE PROJECTIVE SPACE LINE BUNDLE COMPLETE Intersected
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Effect of diluent and reaction parameter on selective oxidation of propane over MoVTeNb catalyst using nanoflow catalytic reactor
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作者 Restu Kartiko Widi Sharifah Bee Abdul Hamid Robert Schlgl 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2008年第2期130-134,共5页
The selective oxidation of propane to acrylic acid over an MoVTeNb mixed oxide catalyst, dried and calcined before reaction has been studied using high-throughput instrumentation, which is called nanoflow catalytic re... The selective oxidation of propane to acrylic acid over an MoVTeNb mixed oxide catalyst, dried and calcined before reaction has been studied using high-throughput instrumentation, which is called nanoflow catalytic reactor. The effects of catalyst dilution on the catalytic performance of the MoVTeNb mixed oxide catalyst in selective oxidation of propane to acrylic acid were also investigated. The effects of some reaction parameters, such as gas hourly space velocity (GHSV) and reaction temperature, for selective oxidation of propane to acrylic acid over diluted MoVTeNb catalyst have also been studied. The configuration of the nanoflow is shown to be suitable for screen catalytic performance, and its operating conditions were mimicked closely to conventional laboratory as well as to industrial conditions. The results obtained provided very good reproducibility and it showed that preparation methods as well as reaction parameters can play significant roles in catalytic performance of these catalysts. 展开更多
关键词 selective oxidation PROPANE acrylic acid MoVTeNb mixed oxide catalyst
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Modeling the Infection Disease (Covid-19) and the Effect of Vaccination
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作者 Hanadi Alzubadi 《Applied Mathematics》 2023年第7期437-449,共13页
In this paper we provide different types of approach in mathematical biology about infection disease and understanding the dynamic of epidemic mathematical models specially in COVID-19 disease which first outbroke in ... In this paper we provide different types of approach in mathematical biology about infection disease and understanding the dynamic of epidemic mathematical models specially in COVID-19 disease which first outbroke in China and fast spread around the world. We work in the connection between the mathematical models and the solution analytically and numerically. At first, we emphasize the Susceptible-Infectious-Recovered (SIR) models’ extension for policy significance. Then, we found the improved SIER model done by research. In third section, we examine the improved model when an appropriate vaccine has been found, we introduce the model of SIR with vaccine term which ends up with discussion and conclusion about the effect of vaccinate. The comprehension of COVID-19 transmission methods, structures, and characteristics is greatly aided by these mathematical models analytically and numerically. 展开更多
关键词 SIR Model SEIR Model COVID-19 Travelling Wave Vaccine Effect Numerical Solution
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Variability of Future Rainfall over the Mono River Basin of West-Africa
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作者 Batablinlè Lamboni Lawin Agnidé Emmanuel +1 位作者 Celestin Manirakiza Zakari Moussa Djibib 《American Journal of Climate Change》 2019年第1期137-155,共19页
This study assessed the rainfall trends and changes over Mono river basin under the highest greenhouse gas emission scenario RCP8.5. Simulations of eight regional climate models (RCMs) provided by Africa-CORDEX progra... This study assessed the rainfall trends and changes over Mono river basin under the highest greenhouse gas emission scenario RCP8.5. Simulations of eight regional climate models (RCMs) provided by Africa-CORDEX program were considered. To analyze the performance of a set of regional climate models, the MBE (mean bias error), the RMSE (root mean square error), the volume bias (VB), correlation coefficient (R2) and the t-Test statistics were calculated. The precipitation concentration index (PCI), Mann-Kendall trend test, Theil-Sen’s slope estimator (β), and relative percentage change methods were also adopted for data analysis. Changes from the baseline period 1981-2010 were computed for far future (2061-2090 and 2071-2100). As results, the analysis herein highlighted the multi-models’ mean ability to simulate the Mono river basin rainfall adequately. Two distinct patterns emerged from the calculated PCI indicating that stations in southern basin will have moderate, irregular, and strongly irregular rainfall concentrations, whereas stations in northern basin will have irregular and strongly irregular rainfall concentrations. Significant declining in the rainfall was detected in most stations for the future period. The evolution of the monthly average rainfall amounts will be broadly characterized by a decrease and increase between 32.4 and 12% with late rainy seasons. It is understood that future changes in rainfall distribution and trends will affect the availability of water for crops, which should affect the productivity of rain fed agriculture. 展开更多
关键词 FUTURE RAINFALL VARIABILITY Trend Change MONO Basin
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Optimization of Planning Routes in Solid Waste Collection
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作者 Thelma Pretel Brandao Vecchit Luiz Mario de Matos Jorge +1 位作者 Mauro Antonio da Silva Sá Ravagnani Paulo Roberto Paraíso 《Journal of Chemistry and Chemical Engineering》 2014年第6期596-601,共6页
This paper presents an optimization model for solving the planning problem of collection and transportation of solid waste in medium-sized cities. As final results, are expected to promote cost savings to the public c... This paper presents an optimization model for solving the planning problem of collection and transportation of solid waste in medium-sized cities. As final results, are expected to promote cost savings to the public coffers, as well as environmental benefits. The developed mathematical model is formulated as a problem of linear programming with mixed-integer variables and transcribed into software GAMS (general algebraic modeling system). The practical application was tested using data collected in the central region of a Brazilian city with approximately 90,000 inhabitants. The deterministic model used allowed an optimal solution. It was found after inclusion of restrictions that eliminated the appearance of sub-routes. It was concluded that the optimal routes allow for a 38% reduction in total distance traveled, which can generate savings of $320.00 per day regarding maintenance and fuel trucks. 展开更多
关键词 Route optimization solid waste collection vehicle routing problem.
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Testing the hypothesis of subtypes of nonadherence in schizophrenia and schizoaffective disorder:A prospective study
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作者 Dulcinea Vega Francisco J Acosta Pedro Saavedra 《World Journal of Psychiatry》 SCIE 2020年第11期260-271,共12页
BACKGROUND Nonadherence is a major problem in the treatment of psychotic disorders.It has been hypothesized that nonadherent patients with schizophrenia are not a homogeneous population and subtypes of nonadherence mi... BACKGROUND Nonadherence is a major problem in the treatment of psychotic disorders.It has been hypothesized that nonadherent patients with schizophrenia are not a homogeneous population and subtypes of nonadherence might exist,but this hypothesis has not been specifically tested.AIM To test the hypothesis of subtypes of nonadherence in schizophrenia and schizoaffective disorder.METHODS This prospective study included 110 consecutively admitted patients diagnosed with schizophrenia or schizoaffective disorder.Assessments were performed at baseline and at 6 mo follow-up after discharge.Sociodemographic,clinical,psychopathological and treatment-related variables were evaluated.Adherence was defined as the concurrence of adherence to antipsychotic treatment and outpatient follow-up during the six-month period.Adherence to antipsychotic treatment was defined as the concurrence of objective and subjective adherence.Sixty-four patients(58%)fulfilled nonadherence criteria at the end of the followup period and were categorized according to their subtype of nonadherence.RESULTS In nonadherent patients(n=64),32(50%)fulfilled criteria of intentional nonadherence,and 32(50%)of unintentional nonadherence(UNA).Unintentional nonadherent patients,as compared to intentional nonadherent patients,are characterized by older age,lower educational level,worse cognitive and negative symptoms,greater severity,worse knowledge of their treatment regimen,greater prevalence of supervision of the treatment,lower number of prior hospitalizations and greater use of nonpsychiatric treatment,anticholinergics and hypnotics.Low educational level(OR=26.1;95%CI:2.819-241),worse treatment knowledge at six months(OR per unit=0.904;95%CI:0.853-0.957)and nonpsychiatric treatment at six months(OR=15.8;95%CI:1.790-139)were independently associated to UNA.CONCLUSION Differentiated subtypes of nonadherence according to intentionality seem to exist in patients with schizophrenia and schizoaffective disorder.Our findings suggest the need for differentiated approach,both in future research and in clinical practice. 展开更多
关键词 Adherence HOSPITALIZATION PSYCHOSIS HYPOTHESIS Unintentional nonadherence Intentional nonadherence
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Uterine Reperfusion Ischemia and Use of Elastic Tourniquet
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作者 J. F. Nnang Essone F. Ovono Abessolo +7 位作者 A. Tsagoulela G. Edjo Nkhilli P. Assoumou J. A. Bang Ntamack E. Anyunzok U. Minkobame J. F. Meye E. Ngou Milama 《Journal of Biosciences and Medicines》 2019年第2期98-119,共22页
Introduction: In humans, it has not been established that the use of elastic tourniquet (ET) during myomectomies, whose delivery times do not exceed 90 minutes, which is responsible for ischemia reperfusion (I/R) syst... Introduction: In humans, it has not been established that the use of elastic tourniquet (ET) during myomectomies, whose delivery times do not exceed 90 minutes, which is responsible for ischemia reperfusion (I/R) systemic. Objectives: To study the plasma variations of markers of I/R during myomectomies performed with ET, whose exposure time does not exceed 90 minutes. Population and methods: Plasma créatinin phosphokinase kinase (CPK) and gluthatione peroxydase (GPX) levels of patients with ET myoma (M + G +, n = 19), taken before, during and after exposure, were compared to those of women operated on myoma without tourniquet (M + G -, n = 15), carriers of unoperated myomas (M + G0, n = 20) and controls (M0G0, n = 18). The duration of exposure of the ET was determined, and perioperative variations of GPX, Ca2+, K+ and CPK between M + G + and others groups were analyzed (p Results: The average duration of exposure of the ET was 51.56 ± 14.12 [30 - 88] min. In M + G +, prior to insertion, CPK was 71.64, GPX 3.537, Ca2+ 3.000, K+ 3.934, and did not vary from those of M + G - (CPK = 59.354, GPX = 3.205, Ca2+ = 2.525, K+ = 3.788), M + G0 (CPK = 71.640, GPX = 2.759, Ca2+ = 3.004, K+ = 3.934) and M0G0 (CPK = 57.2, GPX = 2.306, Ca2+ = 2.879, K+ = 3.705). Conversely, during the posture (CPK = 95.665, GPX = 3.645, Ca2+ = 3.642, K+ = 4.757) and after the release of the ET (CPK = 135.443, GPX = 3.694, Ca2+ = 3.892, K+ = 5.322), these rates were higher among the M + G + compared to the M + G0 and M0G0, but did not differ from those of the M + G - during (CPK = 91.270, GPX = 3.413, Ca2+ = 3.068, K+ = 4.257) and after release (CPK = 137.776, GPX = 3.632, Ca2+ = 3.148, K+ = 5.075). Conclusion: The plasmatic concentration of ischemia (CPK, K+) and reperfusion (GPX, Ca2+) biomarkers does not differ between M + G + and M + G -, but is elevated relatively to controls (M0G0), but also to M + G0’s group. These results show that, for exposure times not exceeding 90 minutes, the elastic tourniquet is probably not the cause of the increase in plasma I/R markers observed in M + G + women. Moreover, these data suggest that the variations of the markers observed during the different surgical stages within each of the two groups of women M + G + and M + G - compared to those of the controls (M0G0) and unoperated myomas (M + G0) are due essentially to the surgical act. 展开更多
关键词 ISCHEMIA REPERFUSION UTERUS ELASTIC TOURNIQUET
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The Correlation between the Intrinsic and Extrinsic Molecular Markers in the Inhibition of the Lungs Carcinogenesis Growth by Mahkota Dewa Polyphenols on Balb/c Mouse
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作者 Theopilus Watuguly Kustarini Samsuria Indranila +2 位作者 Suharyo Hadisaputro Edi Dharmana Lyle E. Craker 《Open Journal of Applied Sciences》 2020年第6期271-286,共16页
<span style="font-family:Verdana;">Phytochemical analysis shows that mahkota dewa fruit contains polyphenols. Mahkota dewa polyphenols have the ability to disrupt or reverse the stages of cancer or a c... <span style="font-family:Verdana;">Phytochemical analysis shows that mahkota dewa fruit contains polyphenols. Mahkota dewa polyphenols have the ability to disrupt or reverse the stages of cancer or a carcinogenesis process by affecting the intracellular signaling tissue molecules involved in an initiation and/or promotion. This chemopreventive potential is highly anticipating. The use, effectiveness, and benefits of the polyphenol have been empirically and pre-clinically proved without side effects. A multivariate analysis using Spearman’s test was conducted to examine the correlation between variables. Meanwhile, to determine which dependent variables played the strong role, a discriminant function analysis was performed with a significance level of p < 0.05 and a reliability level of 95%. The results showed that the mahkota dewa polyphenols acted as the suppressor agent by inducing apoptosis. This finding proved that polyphenols addition might result in death signal transduction through an apoptosis pathway which is either mediated by death receptor or mitochondria. The results of this study indicate that there is a relationship between apoptotic cell death mediated by death receptor and mitochondria through the administration of mahkota dewa polyphenols, it can be argued that mahkota dewa polyphenols can function in lung cancer chemoprevention in mice strain Balb/c.</span> 展开更多
关键词 POLYPHENOLS Lungs Carcinogenesis Molecular Markers p53 Bcl-2 Bax CASPASE-8 Caspase-9 Caspase-3
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A Fourth-order Covergence Newton-type Method 被引量:3
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作者 WANG Xia ZHAO Ling-ling 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2008年第4期589-593,共5页
A fourth-order convergence method of solving roots for nonlinear equation, which is a variant of Newton's method given. Its convergence properties is proved. It is at least fourth-order convergence near simple roots ... A fourth-order convergence method of solving roots for nonlinear equation, which is a variant of Newton's method given. Its convergence properties is proved. It is at least fourth-order convergence near simple roots and one order convergence near multiple roots. In the end, numerical tests are given and compared with other known Newton and Newton-type methods. The results show that the proposed method has some more advantages than others. It enriches the methods to find the roots of non-linear equations and it is important in both theory and application. 展开更多
关键词 Newton iteration method root-finding method fourth-order convergence numerical test
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A New Filled Function with One Parameter to Solve Global Optimization 被引量:6
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作者 Hongwei Lin Huirong Li 《Open Journal of Optimization》 2015年第1期10-20,共11页
In this paper, a new filled function with only one parameter is proposed. The main advantages of the new filled function are that it not only can be analyzed easily, but also can be approximated uniformly by a continu... In this paper, a new filled function with only one parameter is proposed. The main advantages of the new filled function are that it not only can be analyzed easily, but also can be approximated uniformly by a continuously differentiable function. Thus, a minimizer of the proposed filled function can be obtained easily by using a local optimization algorithm. The obtained minimizer is taken as the initial point to minimize the objective function and a better minimizer will be found. By repeating the above processes, we will find a global minimizer at last. The results of numerical experiments show that the new proposed filled function method is effective. 展开更多
关键词 GLOBAL Optimization FILLED Function Method SMOOTHING Technique GLOBAL Minimize Local MINIMIZER
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Adsorption and desorption phenomena on thermally annealed multi-walled carbon nanotubes by XANES study 被引量:2
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作者 Camile Rodolphe Tchenguem Kamto Bridinette Thiodjio Sendja Jeannot Mane Mane 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第9期145-149,共5页
The multi-walled carbon nanotubes(MWCNTs) studied in this work were synthesized by the catalytic chemical vapor deposition(CCVD) process, and were thermally annealed by the hot filament plasma enhanced(HF PE) method a... The multi-walled carbon nanotubes(MWCNTs) studied in this work were synthesized by the catalytic chemical vapor deposition(CCVD) process, and were thermally annealed by the hot filament plasma enhanced(HF PE) method at 550℃ for two hours.The x-ray absorption near edge structure(XANES) technique was used to investigate the adsorption and desorption phenomena of the MWCNTs at normal and grazing incidence angles.The adsorbates were found to have different sensitivities to the thermal annealing.The geometry of the incident beam consistently gave information about the adsorption and desorption phenomena.In addition, the adsorption of non-intrinsic potassium quantitatively affected the intrinsic adsorbates and contributed to increase the conductivity of the MWCNTs.The desorption of potassium was almost 70% greater after the thermal annealing.The potassium non-intrinsic adsorbates are from a physisorption mechanism whereas the intrinsic adsorbates result from chemisorption. 展开更多
关键词 multi-walled carbon NANOTUBES thermal ANNEALING adsorption DESORPTION
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A PROJECTION-TYPE ALGORITHM FOR SOLVING GENERALIZED MIXED VARIATIONAL INEQUALITIES 被引量:2
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作者 涂凯 夏福全 《Acta Mathematica Scientia》 SCIE CSCD 2016年第6期1619-1630,共12页
We propose a projection-type algorithm for generalized mixed variational in- equality problem in Euclidean space Rn. We establish the convergence theorem for the pro- posed algorithm, provided the multi-valued mapping... We propose a projection-type algorithm for generalized mixed variational in- equality problem in Euclidean space Rn. We establish the convergence theorem for the pro- posed algorithm, provided the multi-valued mapping is continuous and f-pseudomonotone with nonempty compact convex values on dom(f), where f : Rn --RU{+∞} is a proper func- tion. The algorithm presented in this paper generalize and improve some known algorithms in literatures. Preliminary computational experience is also reported. 展开更多
关键词 projection-type algorithm generalized mixed variational inequality f-pseudo-monotone mapping
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Spatial and temporal temperature variations in Xinjiang,China during 1961-2008 被引量:4
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作者 YanWei Zhang WenShou Wei +6 位作者 FengQing Jiang MingZhe Liu WenWen Wang Lei Bai KaiFeng Li Rui Shao ZhiWen Dong 《Research in Cold and Arid Regions》 2012年第1期74-82,共9页
This study examines spatial and temporal changes in 16 extreme temperature indices at 37 weather stations in Xinjiang and their associations with changes in climate means during 1961-2008. Linear regression analyses r... This study examines spatial and temporal changes in 16 extreme temperature indices at 37 weather stations in Xinjiang and their associations with changes in climate means during 1961-2008. Linear regression analyses reveal that significant increas- ing trends in temperature were observed over Xinjiang, with the rate of 0.13 ~C/decade, 0.24 ~C/decade, and 0.52 ~C/decade for annual mean temperature, annual maximum, and minimum temperature, respectively. Annual fi'equency of cool nights (days) has decreased by -2.45 days/decade (-0.86 days/decade), whereas the frequency of warm nights (days) has increased by 4.85 days/decade (1.62 days/decade). Seasonally, the frequencies of summer warm nights and days are changing more rap- idly than the corresponding frequencies for cool nights and days. However, normalization of the extreme and mean series shows that the rate of changes in extreme temperature events are generally less than those of mean temperatures, except for winter cold nights which are changing as rapidly as the winter mean minimum temperatures. These results indicate that there have been seasonally and diurnally asymmetric changes in extreme temperature events relative to recent increases in tempera- ture means in Xinjiang. 展开更多
关键词 climate change TEMPERATURE trend analysis XINJIANG
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Changes in daily climate extremes in Xinjiang, northwestern China 被引量:1
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作者 WenWen Wang 《Research in Cold and Arid Regions》 CSCD 2013年第2期240-250,共11页
Based on daily maximum and minimum surface air temperature and precipitation records at 48 meteorological stations in Xinjiang, the spatial and temporal distributions of climate extreme indices have been analyzed duri... Based on daily maximum and minimum surface air temperature and precipitation records at 48 meteorological stations in Xinjiang, the spatial and temporal distributions of climate extreme indices have been analyzed during 1961-2008. Twelve temperature ex- treme indices and six precipitation extreme indices are studied. Temperature extremes are highly correlated to annual mean tem- perature, which appears to be significantly increasing by 0.08 ℃ per year, indicating that changes in temperature extremes reflect consistent warming. The warming tendency is clearer at stations in northern Xinjiang as reflected by mean temperature. The fre- quencies of cold days and nights have both decreased, respectively by -0.86 and -2.45 d/decade, but the frequencies of warm days and nights have both increased, respectively by +1.62 and +4.85 d/decade. Over the same period, the number of frost days shows a statistically significant decreasing trend of-2.54 d/decade. The growing season length and the number of summer days exhibit significant increasing trends at rates of +2.62 and +2.86 d/decade, respectively. The diumal temperature range has de- creased by -0.28 ℃/decade. Both annual extreme low and high temperatures exhibit significant increasing trend, with the former clearly larger than the latter. For precipitation indices, regional annual total precipitation shows an increasing trend and most other precipitation indices are strongly correlated with annual total precipitation. Average wet day precipitation, maximum 1-day and 5-day precipitation, and heavy precipitation days show increasing trends, but only the last is statistically significant. A decreasing trend is found for consecutive dry days. For all precipitation indices, stations in northwestern Xinjiang have the largest positive trend magnitudes, while stations in northern Xiniiang have the largest negative magnitudes. 展开更多
关键词 climate extremes precipitation indices XINJIANG
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