检索结果-南通市图书馆

A Joint Laplace Transform for Pre-exit Diffusion of Occupation Times

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2017年第4期33卷 509-525页

作者： ye CHEN Xiang qun YANG Ying qiu LI Xiao Wen ZHOU College of Mathematics and Computer Science Hu'nan Normal University College of Mathematics and Computational Science Hu’nan University of Arts and Science College of Mathematics and Statistics Changsha University of Science and Technology Department of Mathematics and Statistics Concordia University

For a < r < b, the approach of Li and Zhou(2014) is adopted to find joint Laplace transforms of occupation times over intervals(a, r) and(r, b) for a time homogeneous diffusion process before it first exits from either a or b. The results are expressed in terms of solutions to the differential equations associated with the diffusions generator. Applying these results, we obtain more explicit expressions on the joint Laplace transforms of occupation times for Brownian motion with drift, Brownian motion with alternating drift and skew Brownian motion, respectively.

关键词： Laplace transform occupation time time-homogeneous diffusion exit time Brownian motion with alternating drift skew Brownian motion

Effect of hydraulic fracturing induced stress field on weak surface activation during unconventional reservoir development

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2023年第5期20卷 3119-3130页

作者： Jie Bai Xiao-qiong Wang Hong-Kui Ge Hu Meng ye-qun Wen Unconventional Petroleum Research Institute China University of Petroleum(Beijing)Beijing102249China State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Unconventional reservoirs usually contain many weak surfaces such as faults,laminae and natural fractures,and effective activation and utilization of these weak surfaces in reservoirs can significantly improve the extraction *** hydraulic fracturing,when the artificial fracture approaches the natural fracture,the natural fracture would be influenced by both the original in-situ stress field and the hydraulic fracturing-induced stress *** this paper,the hydraulic fracturing-induced stress field is calculated based on the relative position of hydraulic fracture and natural fracture,the original in-situ stress,the net pressure inside the hydraulic fracture and the pore pressure of the ***,the stability model of the natural fracture is established by combining the Mohr-Coulomb rupture criterion,and extensive parametric studies are conducted to explore the impact of each parameter on the stability of the natural *** validity of the proposed model is verified by comparing with the reservoir characteristics and fracturing process of the X-well 150e155 formation in the Songliao *** is found that the stress field induced by the hydraulic fracture inhibits the activation of the natural fracture after the artificial fracture crossed the natural ***,for similar reservoirs as X-well 150e155,it is suggested to connect natural fractures with hydraulic fractures first and then activate natural fractures which can effectively utilize the natural fractures and form a complex fracture network.

关键词： Hydraulic fracturing Induced stress field Weak surface Natural fracture stability Fracturing characteristics

Luminescent properties of a new Nd^(3+)-doped complex with two different carboxylic acids and pyridine derivative

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2013年第5期32卷 490-495页

作者： Yun-Xia ye Li-Hua Wei Wei-Chen Mei Chen Yin-qun Hua School of Mechanical Engineering Jiangsu University Institute of Laser Technology Jiangsu University School of Material Engineering Jiangsu University

A new Nd3＋-doped organic complex featuring two different perfluorinated carboxylic acids as the first ligand and pyridine derivative 2-amino-3-chloro-5-（tri- fluoromethyl）pyridine as the second ligand was designed and synthesized. Successful coordination between the ligands and central rare earth ions was confirmed by Fourier transform infrared spectroscopy （FT-IR） spectra, 1H nuclear magnetic resonance （1H NMR） spectra, and UV spectra, and the synthesized complex is inferred to be eight-coordinate structure. Solution of the complex dis- solved in DMSO-d6 was prepared and then its fluorescence spectrum, UV-Vis-NIR absorption spectrum, and fluorescence decay curve were tested. The fluorescent lifetime is about 7 txs. Based on the above experimental research, Judd-Ofelt analysis was carried out, and the results indi- cate that appropriate coordination environment around Nd3＋ in this solution results in a high fluorescent quantum efficiency 2 % and a large stimulated emission cross-section about 3.2 × 10^-20 cm^2 at 1,064 nm.

关键词： Nd Organic solution Liquid laser Quantum efficiency Judd-Ofelt theory

PEMFC Identification Based on a Fractional-Order Hammerstein State-Space Model with ADE-BH Optimization

在线全文

学校读者我要写书评

暂无评论

China Petroleum Processing & Petrochemical Technology 2023年第2期25卷 155-164页

作者： qin Hao qi Zhidong ye Weiqin Sun Chengshuo Nanjing University of Science and Technology Nanjing 210094China

Considering the fractional-order and nonlinear characteristics of proton exchange membrane fuel cells(PEMFC),a fractional-order subspace identification method based on the ADE-BH optimization algorithm is proposed to establish a fractional-order Hammerstein state-space model of ***,a Hammerstein model is constructed by connecting a linear module and a nonlinear module in series to precisely depict the nonlinear property of the *** the modeling process,fractional-order theory is combined with subspace identification,and a Poisson filter is adopted to enable multi-order derivability of the data.A variable memory method is introduced to reduce computation time without losing ***,to improve the optimization accuracy and avoid obtaining locally optimum solutions,a novel ADEBH algorithm is employed to optimize the unknown parameters in the identification *** this algorithm,the Euclidean distance serves as the theoretical basis for updating the target vector in the absorption-generation operation of the black hole(BH)***,simulations demonstrate that the proposed model has small output error and high accuracy,indicating that the model can accurately describe the electrical characteristics of the PEMFC process.

关键词： PEMFC Hammerstein model Fractional subspace identification ADE-BH optimization

Bromate removal by gamma irradiation in aqueous solutions

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2016年第1期27卷 44-49页

作者： Zhao-Lian ye Xue-Hui Fang Hui-qi Hou College of Chemistry and Environmental Engineering Jiangsu University of Technology Department of Environmental Science and Engineering Fudan University

Bromate(BrO_3) is a disinfection by-product in drinking water, and its removal is very difficult especially at low levels.60 Co gamma rays were used to remove BrO_3in aqueous solution in this study. The effects of absorbed doses, BrO_3initial concentration, gas saturation, p H value and coexisting anions(Cl, NO 3, SO2 4and HCO 3=CO_3^(2 -))on BrO_3reduction were evaluated. After 4.0-k Gy irradiation of air-equilibrated solution of 30.7 lg/L BrO_3, the residual BrO_3was 8.3 lg/L, which is below the maximum contaminant level of drinking water. The BrO_3reduction rate increased with the dose, in the order of N2[ air [ O_2[ N_2O atmosphere under similar conditions. The results also show that high p H favored the BrO_3removal. According to the experimental results, it can be concluded that the efficiency of decomposing BrO_3by reactive species followed the order of e aq[ H [ HO_2 [ O_2. Coexisting Cl, HCO 3=CO_3^(2 -)and SO2 4ions have little effect on BrO_3removal, whereas NO_3can inhibit its removal as a result of competition with BrO_3for e aq.

关键词： γ射线照射水溶液溴酸盐吸收剂量二氧化碳高pH值消毒副产物含气饱和度

Electrospun nanofibrous membranes with antimicrobial activity for air filtration

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第10期35卷 147-157页

作者： Guangyao Wang Zhitong Xu ye qi Yueguang Fang Guiling Ning Junwei ye State Key Laboratory of Fine Chemicals and School of Chemical Engineering Dalian University of TechnologyDalian 116012China Engineering Laboratory of Boric and Magnesic Functional Material Preparative and Applied Technology Dalian 116024China

Air pollution,including airborne pathogens and particulate matter(PM),has become a prominent issue affecting human health and *** air filtration materials do not meet the requirements for efficient PM capture or do not instantly kill pathogens,leading to increased risk of direct/indirect contact transmission and infection due to the accumulation of pathogens during *** nanofibrous membranes have emerged as a promising platform due to their rich porous structure,finer fiber diameters,good internal connectivity,and the ability to easily incorporate active chemicals for antimicrobial *** this review,antimicrobial mechanisms of nanofibrous membranes for air filtration and PM capture mechanisms of nanofibers were firstly investigated,and various types of electrospun nanofibrous membranes with different antimicrobial agents for efficient air filtration were described in detail,including organic antimicrobial agents,inorganic antimicrobial agents and metal-organic *** hope this work could provide a better practical insight for designing novel electrospun nanofibrous membranes with antimicrobial efficacy for efficient air filtration.

关键词： Electrospinning Nanofibrous membrane Antimicrobial Particulate matter Airfiltration

3D Genome Tuner:Compare Multiple Circular Genomes in a 3D Context

在线全文

学校读者我要写书评

暂无评论

Genomics, Proteomics & Bioinformatics 2009年第3期7卷 143-146页

作者： qi Wang qun Liang Xiuqing Zhang Beijing Institute of Genomics Chinese Academy of Sciences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Beijing Genomics Institute at Shenzhen Shenzhen 518083 China

Circular genomes, being the largest proportion of sequenced genomes, play an important role in genome analysis. However, traditional 2D circular map only provides an overview and annotations of genome but does not offer feature-based comparison. For remedying these shortcomings, we developed 3D Genome Tuner,a hybrid of circular map and comparative map tools. Its capability of viewing comparisons between multiple circular maps in a 3D space offers great benefits to the study of comparative genomics. The program is freely available （under an LGPL licence） at http：//***/projects/dgenometuner.

关键词： three dimensional circular map genome browser comparative genomics

Facile modification of aluminum hypophosphate and its flame retardancy for polystyrene

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2023年第8期60卷 90-98页

作者： Wensheng Li Liangyuan qi Daolin ye Wei Cai Weiyi Xing State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215123China Suzhou Key Laboratory of Urban Public Safety Suzhou Institute for Advanced StudyUniversity of Science and Technology of ChinaSuzhou 215000China

A phosphorus-containing flame retardant, aluminum hypophosphite(AHPi), has been modified by(3-aminopropyl) triethoxysilane(KH550) to prepare flame-retardant polystyrene(PS). The influence of modified AHPi on the morphology and characterization was investigated, and differences in flame retardant properties of the PS/AHPi and PS/modified AHPi were compared. The PS composite can pass the vertical burning tests(UL-94 standard) with a V-0 rating when the mass content of modified AHPi reaches20%, compared with the mass content of 25% AHPi. The element mapping of the PS composite shows that modified AHPi has better dispersion in PS than AHPi. Thermogravimetric analysis results indicated that adding modified AHPi can advance the initial decomposition temperature of the composite *** the addition of modified AHPi, the decrease in peak heat release rate(p HRR) is more evident than AHPi, and the char yield of the resultant PS composites gradually increased. With the addition of 25%modified AHPi, the p HRR and total heat release of PS composites decreased by 81.4% and 37.6%. The modification of AHPi promoted its dispersion in the PS matrix and improved the char formation of PS composites. The results of real-time infrared spectrometry of PS composites, Fourier transform infrared spectra and X-ray photoelectron analysis of the char layer indicated that modified AHPi has flame retardancy in condensed and gas phases.

关键词： Nanomaterials Safety Thermodynamic properties Aluminum hypophosphite Char formation mechanism

A partition of unity level set method with moving knot CS-RBFs for optimizing variable stiffness composites

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第4期36卷 565-572页

作者： Gen LI ye TIAN Kang YANG Tielin SHI qi XIA State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

A partition of unity level set method with moving knot Compactly Supported Radial Basis Functions(CS-RBFs)is proposed for optimizing variable stiffness composite *** iso-contours of a level set function are utilized to represent the curved fiber paths,and the tan-gent vector of the iso-contour defines the orientation of *** level set function of the full design domain is constructed according to the Partition of Unity(POU)method by a set of local level set functions defined on an array of overlapping subdomains,and they are constructed by using the *** positions of knots are iteratively changed during the optimization to improve the performance of composite *** examples of compliance minimization are presented.

关键词： Composite structures Moving knots Partition of unity Radial basis functions Structural optimization