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Functional Limit Theorems for C-R Increments of lp-Valued Wiener Processes in the Norm

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Acta Mathematica Sinica,English Series 2005年第3期21卷 517-532页

作者： qi cai WEI Department of Mathematics Huazhong University of Science & Technology Wuhan 430074 P. R. China Department of Mathematics & Physics Wuhan Polytechnic University Wuhan 430023 P. R. China

In this paper, based on accurately large deviation formulae established in strong topology generated by the Holder norm for l^2-valued Wiener processes, we obtain the functional limit theorems for C-R increments of l^... 详细信息

关键词： Large deviations C-R increments l^p-valued Wiener processes Holder norm

Synthesis of High Molecular Weight Polyethylene and E-MA Copolymers Using Iminopyridine Ni(Ⅱ) and Pd(Ⅱ) Complexes Containing a Flexible Backbone and Rigid Axial Substituents

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Chinese Journal of Polymer Science 2023年第2期41卷 233-239页

作者： Yu-Dan Liao qi cai Sheng-Yu Dai School of Chemical and Environmental Engineering Anhui Polytechnic UniversityWuhu241000China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationAnhui UniversityHefei230601China

Suppressing the chain transfer reactions during polymerization in late-transition metal-catalyzed olefin polymerization systems is the key to obtaining high molecular weight polyolefin materials. In this work, two efficient strategies(“sandwich” and rotation-restricted strategies)to retard chain transfer reactions in ethylene(co)polymerization were employed for the iminopyridyl system. Herein, a family of iminopyridyl Ni(Ⅱ)and Pd(Ⅱ) complexes with a flexible backbone and rigid axial bulky aryl substituents were designed, synthesized and characterized. In ethylene polymerization, the iminopyridyl Ni(Ⅱ) and Pd(Ⅱ) catalysts using the two strategies exhibited reasonable activities and generated highly branched polyethylenes with high molecular weights, where catalysts with dibenzosuberyl substituents exhibited significantly higher activities and produced higher molecular weight polyethylene than catalysts with 8-arylnaphthalenyl substituent. A similar trend of activities and molecular weights was also found in the copolymerization of ethylene with MA using the Pd(Ⅱ) catalysts. Moreover, highly branched E-MA copolymers with moderate to high molecular weights and high incorporation ratios(up to 17.4 mol%) were generated with the two Pd(Ⅱ) catalysts. Most interestingly, as compared with the dibenzhydryl Ni(Ⅱ) and Pd(Ⅱ) catalysts, the catalysts using the two strategies exhibited a superior ability to retard the chain transfer reactions and generated polymers and copolymers with 1-2 orders of magnitude higher molecular weights during ethylene(co)polymerization.

关键词： Ni(Ⅱ)and Pd(Ⅱ) Suppressing chain transfer High molecular weight Ethylene(co)polymerization

Optimal Reinsurance and Investment Policies with the CEV Stock Market

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Acta Mathematicae Applicatae Sinica 2016年第3期32卷 647-658页

作者： qi-cai LI Meng-di GU School of Mathematical Sciences Nanjing Normal University Antai College of Economics and Management Shanghai Jiaotong University

In this paper, under the criterion of maximizing the expected exponential utility of terminal wealth, we study the optimal proportional reinsurance and investment policy for an insurer with the compound Poisson claim process. We model the price process of the risky asset to the constant elasticity of variance （for short, CEV） model, and consider net profit condition and variance reinsurance premium principle in our work. Using stochastic control theory, we derive explicit expressions for the optimal policy and value function. And some numerical examples are given.

关键词： proportional reinsurance CEV model stochastic control Hamilton-Jacobi-Bellman equation exponential utility

Optimization model analysis of centralized groundwater source heat pump system in heating season

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Frontiers in Energy 2015年第3期9卷 343-361页

作者： Shilei LU Yunfang qi Zhe cai Yiran LI School of Environmental Science and Engineering Tianjin University Tianjin 300072 China

The ground-water heat-pump system （GWHP） provides a high efficient way for heating and cooling while consuming a little electrical energy. Due to the lack of scientific guidance for operating control strategy, the coefficient of performance （COP） of the system and units are still very low. In this paper, the running strategy of GWHP was studied. First, the groundwater thermal transfer calculation under slow heat transfixion and transient heat transfixion was established by calculating the heat transfer simulation software Flow Heat and using correction factor. Next, heating parameters were calculated based on the building heat load and the terminal equipment characteristic equation. Then, the energy consumption calculation model for units and pumps were established, based on which the optimization method and constraints were established. Finally, a field test on a GWHP system in Beijing was conducted and the model was applied. The new system operation optimization idea for taking every part of the GWHP into account that put forward in this paper has an important guiding significance to the actual operation of underground water source heat pump.

关键词： optimization model groundwater source heatpump system theoretical analysis example verification,heating season

Effects of Cr Content and Annealing Temperature on Microstructure and Wear Characteristics of Cast Ausferrite Nodular Iron

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Journal of Iron and Steel Research International 2015年第11期22卷 1049-1054页

作者： Jia-peng ZOU Kazumichi SHIMIZU qi-zhou cai State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology Department of Materials Science and Engineering Muroran Institute Technology

The effects of Cr content and annealing temperature on abrasive wear characteristics of cast ausferrite nodular iron were investigated with Suga type abrasive wear tester. The surface morphology and Vickers hardness of the tested samples were analyzed by scanning electron microscopy（SEM）, digital microscope and Vickers hardness tester. The results show that the cast ausferrite nodular iron could be obtained by alloying with Cr in the as-cast ductile cast iron and permanent mold casting, and the bainite content in the matrix increased with increasing Cr content. However, the decomposition of bainite took place during annealing at 500 °C to 800 °C; especially, at 800 °C, the bainite transformed into a mixture of fine lamellar pearlite and ferrite matrix structure. The wear loss of specimens was reduced with increasing Cr content in the cast ausferrite nodular iron. The wear loss of the sample cast ausferrite nodular iron with 0.4mass% Cr is the least. The wear loss began to increase while the Cr content is 0.6mass%. The wear loss of annealed ductile irons at different annealing temperatures was higher than that of as-cast samples. During the abrasive wear, the shear stress transformed austenite to martensite, and the hardness of specimens increased and the wear resistance of as-cast ductile cast iron was improved.

关键词： cast ausferrite nodular iron Cr content annealing temperature microstructure wear characteristics

Experimental and theoretical study of coupled influence of flow velocity increment and particle size on particle retention and release in porous media

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Water Science and Engineering 2017年第3期10卷 236-245页

作者： Xing-xin Chen qi-peng cai Zhong-han Wu School of Transportation Southeast University School of Civil Engineering Huaqiao University School of Civil Engineering Beijing Jiaotong University

Experimental and theoretical studies were carried out to investigate the coupled influence of flow velocity increment and particle size on the retention and release of particles in porous media. Particle release was examined through measurement of changes in effluent particle concentrations, and particle retention was assessed through measurement of the final spatial distribution of particles remaining in the soil columns after the experiments. Particle release curves were simulated using a convection-dispersion model that includes the instantaneous release of the line source. Fitted model parameters were used to gain insights into the mechanisms that control particle retention and release. When the flow velocity increment was 0.0435 cm/s, the peak concentration of particles decreased with increasing flow velocity until the latter approached a critical level, beyond which the particle concentration increased. Particle wedging and fouling were considered the primary mechanisms that controlled particle retention and release beyond the critical particle velocity. In experiments with large flow velocity increments, small particles exhibited lower particle mass fraction than large particles as particle wedging and fouling increased with particle size. The range of longitudinal dispersivity decreased with an increasing particle size and flow velocity increment. Moreover, the mean particle velocity increased with the mean interstitial fluid velocity. The mean particle velocity profile was highly sensitive to the particle size at low velocity increments. In general,particle release rates increased with both flow velocity and velocity increment. The mass of the released particles provides further evidence that particle wedging and fouling are the major factors that control particle release in sand columns.

关键词： Particle Porous media Retention Release Hydrodynamic force

In situ investigation on densification mechanism of Ti-20Al-19Nb(at.%)alloy by TiH_(2)-assisted pressureless sintering

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Journal of Materials Science & Technology 2023年第34期165卷 170-186页

作者： qi cai qilin Yu Xinyao Li Yao Lu Yanmo Li Ganggang Cui School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Welding Engineering and Laser Processing Centre Cranfield UniversityBedfordshireMK43 OALUK Luoyang Ship Material Research Institute Luoyang 471023China

Dense Ti-20Al-19Nb(at.%)alloys can be cost-effectively fabricated by TiH_(2)-assisted pressureless sintering;nevertheless,the densification mechanism remains controversial without understanding the entire sintering *** in situ observing the surface morphology of the Ti/Al/Nb and Ti/TiH_(2)/Al/Nb compacts upon heating,the densification mechanism of the Ti-20Al-19Nb alloys was elucidated in this *** addition to the reported reason that the dehydrogenation of TiH_(2)provided reactive Ti,the densification of Ti-20Al-19Nb alloy was found to be strongly associated with the phase transformations upon *** TiH_(2)participated in the reverse eutectoid transformation,α-Ti+δ-TiH_(2)→β-Ti,inducing theα/βand TiH_(2)/βgrain boundaries for the rapid diffusion of *** reaction of Ti(s)+Al(s)→TiAl_(3)(s)was then accelerated,and the majority of the Al phase was consumed in the solid state,which significantly reduced the pores from the transient liquid *** activation energy of the Ti-Al reaction decreased with the addition of TiH_(2),and the growth mode of the TiAl_(3)phase was *** removing the large pores at 700℃,the Ti-Al intermetallic phases were well connected,forming the continuous interdiffusion route for Ti,Al,and *** diffusion of Nb,as well as the phase transformation ofα2→B2,was then promoted,and the ripening time for the B2 phase was *** a result,the density and mechanical properties were *** initial results of this study provided a foundation for the cost-effective fabrication of high-strength Ti-Al alloys containing refractory elements.

关键词： Ti-Al-Nb alloy Sintering mechanism Porosity In situ observation Phase transformation

Disease Recognition of Apple Leaf Using Lightweight Multi-Scale Network with ECANet

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Computer Modeling in Engineering & Sciences 2022年第9期132卷 711-738页

作者： Helong Yu Xianhe Cheng Ziqing Li qi cai Chunguang Bi College of Information Technology Jilin Agricultural UniversityChangchun130118China

To solve the problem of difficulty in identifying apple diseases in the natural environment and the low application rate of deep learning recognition networks,a lightweight ResNet(LW-ResNet)model for apple disease recognition is *** on the deep residual network(ResNet18),the multi-scale feature extraction layer is constructed by group convolution to realize the compression model and improve the extraction ability of different sizes of lesion *** improving the identity mapping structure to reduce information *** introducing the efficient channel attention module(ECANet)to suppress noise from a complex *** experimental results show that the average precision,recall and F1-score of the LW-ResNet on the test set are 97.80%,97.92%and 97.85%,*** parameter memory is 2.32 MB,which is 94%less than that of *** with the classic lightweight networks SqueezeNet and MobileNetV2,LW-ResNet has obvious advantages in recognition performance,speed,parameter memory requirement and time *** proposed model has the advantages of low computational cost,low storage cost,strong real-time performance,high identification accuracy,and strong practicability,which can meet the needs of real-time identification task of apple leaf disease on resource-constrained devices.

关键词： Apple disease recognition deep residual network multi-scale feature efficient channel attention module lightweight network

Role of circular RNAs in gastrointestinal tumors and drug resistance

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World Journal of Clinical Cases 2021年第34期9卷 10400-10417页

作者： Shi-Jun Xi Wen-qi cai qin-qi Wang Xiao-Chun Peng Department of Pathophysiology School of Basic MedicineHealth Science CenterYangtze UniversityJingzhou 434023Hubei ProvinceChina

The incidence of gastrointestinal cancers has increased significantly over the past decade and gastrointestinal malignancies now rank among the leading causes of mortality *** newer therapeutic strategies such as targeted therapies have greatly improved patient outcomes,their clinical success is limited by drug resistance,treatment failure and recurrence of metastatic ***,there is an urgent need for further research identifying accurate and reliable biomarkers for precise treatment *** RNAs(circRNAs)exhibit a covalently closed structure,high stability and biological conservation,and their expression is associated with the occurrence and development of gastrointestinal ***,circRNAs may significantly influence drug resistance of gastrointestinal *** this article,we review the role of circRNAs in the occurrence and development of gastrointestinal cancer,their association with drug resistance,and potential application for early diagnosis,treatment and prognosis in gastrointestinal ***,we summarize characteristics of circRNA,including mechanism of formation and biological effects via mRNA sponging,chromatin replication,gene regulation,translational modification,signal transduction,and damage ***,we discuss whether circRNA-related noninvasive testing may be clinically provided in the *** review provides new insights for the future development of diagnostics and therapeutics based on circRNAs in gastrointestinal tumors.

关键词： Gastrointestinal cancer Circular RNA Drug resistance Genomics Targeted therapy Molecular mechanics